The Data Release Eight of LAMOST Low-Resolution Spectroscopic Survey (LRS)

Section 1. Overview

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope   (LAMOST) is a Chinese national scientific research facility operated by the National Astronomical Observatories, Chinese Academy of Sciences. It is a special reflecting Schmidt telescope with 4000 fibers in a field of view of 20 deg2 in the sky. Until July 2020, LAMOST has completed its pilot survey, which was launched in October 2011 and ended in June 2012, and the regular survey of the first eight years, which was initiated on September 2012[1-4]. In this data release, there are totally 10,633,515 low resolution spectra published, which satisfy the selection criteria that the LAMOST LRS General Catalog also used. The data products of this release can be available from the website http://www.lamost.org/dr8/v2.0/, and they include:

1.    Spectra. - There are 10,633,515 flux (relatively) - and wavelength-calibrated, sky-subtracted spectra, including 10,336,752 stellar spectra, 224,702 galaxy spectra, and 72,061 quasar spectra, and they cover the wavelength range of 3700 Å - 9000 Å with a resolution of 1800[2-3] at the 5500 Å.

2.    Spectroscopic Parameter Catalogs. - In this data release, 11 spectroscopic parameter catalogs are also published,and they are the LAMOST LRS General Catalog, the LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars, the LAMOST LRS Line-Index Catalog of A Type Stars, the LAMOST LRS Catalog of gM, dM, and sdM Stars, the LAMOST LRS Multiple Epoch Catalog, the LAMOST LRS Observed Plate Information Catalog, the LAMOST LRS Input Catalog, the LAMOST LRS Catalog of Cataclysmic Variable Stars, the LAMOST LRS Catalog of White Dwarf Stars, the LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies, and LAMOST LRS Catalog of Emission Line Features of QSOs, respectively. More than a hundred parameters are included in these catalogs, such as right ascension, declination, signal to noise ratio (S/N), Gaia source identifier and magnitudes, atmospheric parameters (effective temperature, surface gravity, and metallicity), radial velocity, element abundance, spectral line indices, line widths, the metallicity sensitive parameter, and the magnetic activity flag.

In section 2, we introduce the released FITS file in detail, and present parameter catalogs in section 3.

Section 2. FITS File

2.1 Designation

In this data release, over ten million FITS files are published on-line, and they are named in the form of “spec-MMMMM-YYYY_spXX-FFF.fits”. “MMMMM”, “YYYY”, “XX”, and “FFF” represent the local modified Julian day (LMJD) which is a non-negative integer, the plan identity string (PLANID), the spectrograph identity number which is between 1 and 16, and the fiber identity number which is in the range of 1 to 250[3]. In addition, we can also get the LAMOST designation for an object from the DESIG keyword, and it is named in the form “LAMOST JHHMMSS.ss+DDMMSS.ss”, where “HHMMSS.ss” is right ascension in unit of HMS, and “+DDMMSS.ss” is declination in unit of DMS.

2.2 Structure

A primary header data unit (HDU), an optional conforming extension, and other optional special records compose a FITS file. The FITS file of each low-resolution spectrum in this data release contains the primary HDU at least, which is followed by a primary data array, and the FITS files of spectra with atmospheric parameters also include the Extension 1. 

The primary extension includes the header file and data array. The primary header file consists of eight groups of keywords, and the primary data array stores the flux, wavelength, inverse variance, andmask, and ormask.

Besides a few basic keywords in the header file of extension 1, the atmospheric parameters, radial velocity, alpha element abundance, and their errors were also included. As the primary data array, there are inverse variance, andmask, and ormask in the data array of extension 1. The difference is that the fluxes and wavelengths of the normalized spectra were stored in the data array of extension 1.

The following sub-section 2.3 and 2.4 will introduce the primary extension and extension 1, respectively.

2.3 Primary Extension

2.3.1 Primary FITS Header

We divided keywords of the primary FITS header into eight groups, and they are mandatory keywords, file information keywords, telescope parameter keywords, observation parameter keywords, spectrograph parameters keywords, weather condition keywords, data reduction parameters keywords and spectra analysis results keywords respectively. We will explain each keyword as follows.

2.3.1.1 Mandatory Keywords

Mandatory keywords are required in every Header Data Unit (HDU), and their value must be written in fixed format.

SIMPLE  =                    T /Primary Header created by MWRFITS v1.11b
BITPIX  =                   -32 /
NAXIS   =                    2 / Number of array dimensions
NAXIS1  =                 3901 /
NAXIS2  =                    5 /
EXTEND  =                   T /

SIMPLE Keyword --- It is required to be the first keyword in the primary header of all FITS file. The value field shall contain a logical constant with the value T if the file conforms to this standard. This keyword is mandatory for the primary header and is not permitted in extension headers. A value of F signifies that the file does not conform to this standard.

BITPIX Keyword --- The value field shall contain an integer, and it shall specify the number of bits that represent a data value. A value of -32 represents IEEE single precision floating point.

NAXIS Keyword --- The value field shall contain a non-negative integer no greater than 999, representing the number of axes in the associated data array. A value of zero signifies that no data follow the header in the HDU.

NAXIS1 and NAXIS2 Keywords --- The value field of these two indexed keywords shall contain a non-negative integer, representing the number of elements along axis n of a data array. The NAXIS1 keyword represents the number of wavelength array, i.e., the column number of the primary data array, and the NAXIS2 keyword indicates the row number of the primary data array.

EXTEND Keyword --- The value field shall contain a logical value indicating whether the FITS file is allowed to contain conforming extensions following the primary HDU. This keyword may only appear in the primary header and must not appear in an extension header. If the value field is T then there may be conforming extensions in the FITS file following the primary HDU. This keyword is only advisory, so its presence with a value T does not require that the FITS file contains extensions, nor does the absence of this keyword necessarily imply that the file does not contain extensions [5].

2.3.1.2 File Information Keywords

FILENAME= 'spec-58170-HD070403N361848V01_sp16-210.fits' /
OBSID   =            648816210 / Unique number ID of this spectrum
AUTHOR  = 'LAMOST Pipeline'    / Who compiled the information
DATA_V  = 'LAMOST DR8'         / Data release version
N_EXTEN =                    1 / The extension number
NORM    =                    1 / 1 if there exists a normalizated spectrum
ORIGIN  = 'NAOC-LAMOST'        / Organization responsible for creating this file
DATE    = '2020-09-14T13:32:41' / Time when this HDU is created (UTC)

FILENAME Keyword --- The value field shall contain a character string giving the name of this FITS file. Take the “spec-58170-HD070403N361848V01_sp16-210.fits” as an example, “58170” is the local modified Julian day, “HD070403N361848V01” is the plan ID, “sp16” is the spectrograph ID, and “210” is the Fiber ID.

OBSID Keyword --- The value field shall be a non-negative integer giving the number ID of this spectrum.

AUTHOR Keyword --- This keyword contains a string constant “LAMOST Pipline”, which represents the author who produce this file.

DATA_V Keyword --- This keyword contains a string constant, which represents the data release version.

N_EXTEN Keyword --- The value field shall contain an integer giving the extension number of a FITS file. For spectra with atmospheric parameters, the value of this field is 2.

NORMKeyword --- The value field shall be a non-negative integer, 1 means there are normalized fluxes in the data array of extension 1, and 0 represents there is no normalized flux in the data array.

ORIGIN Keyword --- This ORIGIN keyword contains a string constant “NAOC-LAMOST”, which indicates the Organization responsible for this FITS file. “NAOC” represents the abbreviation of National Astronomical Observatories, Chinese Academy of Sciences.

DATE Keyword --- The value field shall contain a character string giving the UTC time when this FITS file is created.

2.3.1.3 Telescope Parameter Keywords

TELESCOP= 'LAMOST  '           / GuoShouJing Telescope
LONGITUD=               117.58 / [deg] Longitude of site
LATITUDE=                40.39 / [deg] Latitude of site
FOCUS   =                19964 / [mm] Telescope focus
CAMPRO  = 'NEWCAM  '           / Camera program name
CAMVER  = 'v2.0    '           / Camera program version

TELESCOP Keyword --- This keyword contains a string constant “LAMOST” giving the name of our telescope.

LONGITUD Keyword --- The keyword contains a floating-point constant, which provide the longitude of Xinglong station where LAMOST is mounted on.

LATITUDE Keyword --- The keyword contains a floating-point constant, which provide the latitude of Xinglong station.

FOCUS Keyword --- The FOCUS keyword gives the telescope focus, and its unit is millimeter.

CAMPRO Keyword --- The value field contain a string constant “NEWCAM”, which shows the name of camera.

CAMVER Keyword --- The value field contain a character string, which gives the present camera program version.

2.3.1.4 Observation Parameter Keywords

DATE-OBS= '2018-02-20T12:48:00' / The observation median UTC
DATE-BEG= '2018-02-20T20:30:18.0' / The observation start local time
DATE-END= '2018-02-20T21:06:58.0' / The observation end local time
LMJD    =                58170 / Local Modified Julian Day
MJD     =                58169 / Modified Julian Day
LMJMLIST= '83764590-83764603-83764616' / Local Modified Julian Minute list
PLANID  = 'HD070403N361848V01' / Plan ID in use
RA      =           103.632286 / [deg] Right ascension of object
DEC     =            37.801677 / [deg] Declination of object
RA_OBS  =           103.632286 / [deg] Right ascension during observing
DEC_OBS =            37.801677 / [deg] Declination during observing
OFFSET  =                    F / Whether there's a offset during observing
OFFSET_V=                 0.00 / Offset value in arcsecond
DESIG   = 'LAMOST J065431.74+374806.0' / Designation of LAMOST target
FIBERID =                  210 / Fiber ID of Object
CELL_ID = 'H1502   '           / Fiber Unit ID on the focal plane
X_VALUE = '636.4868805740'     / [mm] X coordinate of object on the focal plane
Y_VALUE = '-545.8922217890'    / [mm] Y coordinate of object on the focal plane
OBJNAME = '259566658905513'    / Name of object
OBJTYPE = 'Star    '           / Object type from input catalog
TSOURCE = 'LEGUE_LCH'          / Name of input catalog
TCOMMENT= '16612266169952852'  / Target information
TFROM   = 'LCH000001'          / Target catalog
FIBERTYP= 'Obj     '           / Fiber type of object
FIBERMAS=                    0 / Bitmask of warning values, 0 means all is well
MAGTYPE = 'gri     '           / Magnitude type of object
MAG1    =                13.47 / [mag] Mag1 of object
MAG2    =                12.95 / [mag] Mag2 of object
MAG3    =                12.75 / [mag] Mag3 of object
MAG4    =                99.00 / [mag] Mag4 of object
MAG5    =                99.00 / [mag] Mag5 of object
MAG6    =                99.00 / [mag] Mag6 of object
MAG7    =                99.00 / [mag] Mag7 of object
OBS_TYPE= 'OBJ     '           / The type of target (OBJ, FLAT, ARC or BIAS)
OBSCOMM = 'Science '           / Science or Test
RADECSYS= 'FK5     '           / Equatorial coordinate system
EQUINOX =              2000.00 / Equinox in years
LAMPLIST= 'lamphgcdne.dat'     / Arc lamp emission line list
SKYLIST = 'skylines.dat'       / Sky emission line list
NEXP    =                    3 / Number of valid exposures
NEXP_B  =                    3 / Number of valid blue exposures
NEXP_R  =                    3 / Number of valid red exposures
EXPT_B  =              1800.00 / [s] Blue exposure duration time
EXPT_R  =              1800.00 / [s] Red exposure duration time
EXPTIME =              1800.00 / [s] Minimum of exposure time for all cameras
BESTEXP =             83764590 / LMJM of the best exposure
SCAMEAN =                 6.90 / [ADU] Mean level of scatter light

DATE-OBS Keyword --- The value field shall contain a character string, which gives the median moment UTC of multiple exposures.

DATE-BEG Keyword --- The value field shall contain a character string giving the observation start Beijing Time.

DATE-END Keyword --- The value field shall contain a character string, which provide the observation end Beijing Time.

LMJD Keyword --- The value field shall be a non-negative integer giving the local modified Julian day.

MJD Keyword --- The value field shall be a non-negative integer giving the modified Julian day.

LMJMLIST Keyword --- The value field shall contain a character string, which shows a list of local modified Julian minute of n times exposures.

PLANID Keyword --- The value field shall contain a character string providing the plan name of the target.

RA Keyword --- The value field shall contain a non-negative real floating-point number, which gives the right ascension of target from the input catalog.

DEC Keyword --- The value field shall contain a real floating-point number, which gives the declination of target from the input catalog.

RA_OBS Keyword --- The value field shall contain a non-negative real floating-point number, which gives the pointing right ascension of target during observation.

DEC_OBS Keyword --- The value field shall contain a real floating-point number, which gives the pointing declination of target during observation.

OFFSET Keyword --- The value field shall contain a boolean value (T or F), which indicates if there is a fiber-offset for the target. The fiber-offset usually applied for the very bright stars (r<11) to avoid CCD saturation.

OFFSET_V Keyword --- The value field shall contain a real floating-point number giving the offset value in unit of arcsec.

DESIG Keyword --- The value field shall contain a character string, which indicates the name of LAMOST target. Like the name of SDSS target, numbers after the character “J” and before “+” represents RA in unit of HMS, and numbers after the character “+” are DEC in unit of DMS.

FIBERID Keyword --- The value field shall contain a non-negative integer between 1 and 250, which shows the fiber ID and shall be used together with the spectrograph ID.

CELL_ID Keyword --- The value field shall contain a character string, which gives the fiber unit ID on the focal plane. LAMOST focal plane is divided into four quadrant named “EFGH” respectively, the first character of this keyword represents the quadrant number, the first two numbers after the first character is the row number in this quadrant, and the next two numbers is the column numbers.

X_VALUE and Y_VALUE Keywords --- The value field shall contain two real floating-point numbers, which give X and Y coordinates of target on the focal plane.

OBJNAME Keyword --- The value field shall contain character string, giving the name ID of object that determined by the RA, DEC and HTM method [6].

OBJTYPE Keyword --- The value field shall contain a character string giving the class of objects in input catalogs.

TSOURCE Keyword --- The value field shall contain a character string which shows the name of organization or person who submit input catalog.

TCOMMENT Keyword --- The value field shall contain a character string which shows the target ID from SDSS, UCAC4, PANSTAR and other catalogues.

TFROM Keyword --- The value field shall contain a character string which shows input catalog submitted by an organization or a person determined by the TSOURCE.

FIBERTYP Keyword --- The value field shall contain a character string, giving the type of fiber assigned to this target. This keyword has six values, i.e., Obj, Sky, F-std, Unused, PosErr and Dead. Obj means the fiber is assigned to an object, including star, galaxy and so on. Sky indicates that the fiber is allocated to take skylight. F-std shows the fiber is used to take the light of a flux calibration standard star. Unused, PosErr and Dead mean the unused fiber, a wrong fiber position, or out of commission respectively.

FIBERMAS Keyword --- The value field shall contain an integer, which is used to show the problems of fibers. If you want to know the exact problem of a fiber, you should first convert the decimal value of “FIBERMAS” to a nine-bit binary number, which is shown in table 1. If the value of a bit is 1, it represents the fiber has associated problem, and the following table 2 lists the associated fiber problem of each bit. 

 

Table 1: Nine bits of the “FIBERMAS” field

9

8

7

6

5

4

3

2

1

 

Table 2: The fiber problems

Bit

Problem

Comment

1

NOALLOTTED

Fiber not allotted

2

BADTRACE

Bad trace from the routine TRACECENTER

3

BADFLAT

Low counts in flat field

4

BADARC

Bad arc solution

5

MANYBADPIXEL

>10% pixels are bad on CCD

6

SATURATED

>10% pixels are saturated

7

WHOPPER

Whopping fiber

8

NEARWHOPPER

Near a whopping fiber

9

BADSKYFIBER

Sky fiber shows extreme residuals

MAGTYPE Keyword --- The value field shall contain a character string, which shows the magnitude type of a target.

MAG1, MAG2, MAG3, MAG4, MAG5, MAG6 and MAG7 Keywords --- The value field shall contain a real floating-point number between 0 and 100, giving the associated magnitudes of MAGTYPE keyword. For example, The MAGTYPE keyword is “ugrizjh”, the MAG1, MAG2, MAG3, MAG4, MAG5, MAG6 and MAG7 keywords provide the magnitudes of u, g, r, i, z, j and h filter respectively.

OBS_TYPE Keyword --- The value field shall contain a character string giving the type of observation targets, which include object, flat, bias and arc lamp.

OBSCOMM Keyword --- The value field shall contain a character string constant representing the observation purposes, which includes observations used for science researches and kinds of tests.

RADECSYS Keyword --- The value field shall contain a character string giving the equatorial coordinate system based on the J2000 position.

EQUINOX Keyword --- The value field shall contain a real floating-point number giving the standard epoch used at present.

LAMPLIST Keyword --- The value field shall contain a character string giving the file name of arc lamp emission line list, which is used in the process of wavelength calibration.

SKYLIST Keyword --- The value field shall contain a character string giving the file name of sky emission line list, which is used in the process of sky subtraction.

NEXP, NEXP_B and NEXP_R Keywords --- The value field of these three keywords shall contain three non-negative integers, which provide numbers of exposures, and numbers of valid blue and red exposures respectively.

EXPT_B and EXPT_R Keywords --- The value fields of these two keywords shall contain two real floating-point numbers, which give exposure duration times of blue and red CCD.

EXPTIME Keyword --- The value field shall contain a real floating-point, which gives the minimum of blue and red total exposures times.

BESTEXP Keyword --- The value field shall contain a integer, which gives the local modified Julian minute of a exposure with maximum S/N in n time exposures.

SCAMEAN Keyword --- The value field shall contain a real floating-point giving the mean level of scatter light, which is the average flux of regions where there is no fiber and is at the left and right edge of a two dimension spectra image.

2.3.1.5 Spectrograph Parameters Keywords

SPID    =                   16 / Spectrograph ID
SPRA    =          104.4324682 / [deg] Average RA of this spectrograph
SPDEC   =           37.9555196 / [deg] Average DEC of this spectrograph
SLIT_MOD= 'x2/3    '           / Slit mode, x1, x2/3 or x1/2

SPID Keyword --- The value field shall contain a non-negative integer numbers between 1 and 16, which provides the spectrograph ID.

SPRA and SPDEC Keywords --- The value field of these two keywords shall contain two real floating-point numbers, which are the averages of RA and DEC of all objects in each spectrograph.

SLIT_MOD Keyword --- The value field shall contain a character string of “x2/3”, which gives the slit mode and responds spectra resolution of 1800 respectively at 4750 Å (blue) and 7350 Å (red).

2.3.1.6 Weather Condition Keywords

TEMPCCDB=              -121.70 / [deg] The temperature of blue CCD
TEMPCCDR=              -110.70 / [deg] The temperature of red CCD
SEEING  =                 3.30 / [arcsec] Seeing during exposure
MOONPHA =                 1.93 / [day] Moon phase for a 29.53 days period
TEMP_AIR=                -3.50 / [deg] Temperature outside dome
TEMP_FP =                -1.10 / [degree celsius] Temprature of the focal plane
DEWPOINT=               -23.40 / [deg]
DUST    = '        '           / Reservation
HUMIDITY=                19.60 /
WINDD   =               153.60 / [deg] Wind direction
WINDS   =                 1.50 / [m/s] Wind speed
SKYLEVEL= '        '           / Reservation

TEMPCCDB Keyword --- The value field shall contain a real floating-point number, which provides the temperature of blue CCD. The unit “degree” represents centigrade degree.

TEMPCCDR Keyword --- The value field shall contain a real floating-point number, which provides the temperature of red CCD. The unit “degree” represents centigrade degree.

SEEING Keyword --- The value field shall contain a real floating-point number giving seeing during exposure, which is calculated by manually measuring the full width at half maximum of guide star image.

MOONPHA Keyword --- The value field shall contain a real floating-point number giving the moon phase.

TEMP_AIR Keyword --- The value field shall contain a real floating-point number giving the temperature outside dome, which is measured by automatic weather instrument. The unit “degree” represents centigrade degree.

TEMP_FP Keyword --- The value field shall contain a real floating-point number giving the temperature of focal plane, which is measured by automatic weather instrument. The unit “degree” represents centigrade degree.

DEWPOINT Keyword --- The value field shall contain a real floating-point number giving the dew-point temperature, which is also measured by the automatic weather instrument. The unit “degree” represents centigrade degree.

DUST Keyword --- The value of this keyword is temporarily empty at present, because the dust measuring instrument is now in debugging, and we will write this parameters into fits header when problems are resolved.

HUMIDITY Keyword --- The value field shall contain a real floating-point number between 0 and 1, which gives humidity in the air.

WINDD Keyword --- The value field shall contain a real floating-point number which records the instantaneous wind direction when start exposure, and the direction of north is the 0 degree wind direction.

WINDS Keyword --- The value field shall contain a real floating-point number which records the instantaneous wind speed when start exposure, and wind direction and speed are also measured also by the automatic weather instrument.

SKYLEVEL Keyword --- This keyword is NULL now, because the instrument is debugging.

2.3.1.7 Data Reduction Parameters Keywords

EXTRACT = 'aperture'           / Extraction method
SFLATTEN=                    T / Super flat has been applied
PCASKYSB=                    T / PCA sky-subtraction has been applied
NSKIES  =                   37 / Sky fiber number
SKYCHI2 =                  2.0 / Mean chi^2 of sky-subtraction
SCHI2MIN=                  1.7 / Minimum chi^2 of sky-subtraction
SCHI2MAX=                  2.4 / Maximum chi^2 of sky-subtraction
NSTD    =                    6 / Number of (good) standard stars
FSTAR   = '216-141-192-191-112-214' / FiberID of flux standard stars
FCBY    = 'auto    '           / Standard stars origin (auto, manual or catalog)
HELIO   =                    T / Heliocentric correction
HELIO_RV=             22.19496 / [km/s] Heliocentric correction
VACUUM  =                    T / Wavelengths are in vacuum
NWORDER =                    2 / Number of linear-log10 coefficients
WFITTYPE= 'LOG-LINEAR'         / Linear-log10 dispersion
COEFF0  =               3.5682 / Central wavelength (log10) of first pixel
COEFF1  =               0.0001 / Log10 dispersion per pixel
WAT0_001= 'system=linear'      /
WAT1_001= 'wtype=linear label=Wavelength units=Angstroms' /
CRVAL1  =               3.5682 / Central wavelength (log10) of first pixel
CD1_1   =               0.0001 / Log10 dispersion per pixel
CRPIX1  =                    1 / Starting pixel (1-indexed)
CTYPE1  = 'LINEAR  '           /
DC-FLAG =                    1 / Log-linear flag

EXTRACT Keyword --- The value field shall contain a character string, which indicates the method of spectrum extraction. In LAMOST spectra reduction pipeline, only the aperture method is applied to spectra extraction.

SFLATTEN Keyword --- The value of this keyword shall be boolean, which represents whether or not use the super flat. In LAMOST spectra reduction pipeline, super flat is used to make the fiber-to-fiber relative efficiency around 1.

PCASKYSB Keyword --- The value of this keyword shall be boolean, which represents whether or not use the PCA method to subtract sky light. In LAMOST spectra reduction pipeline, the PCA method is used to subtract sky light at the wavelength range larger than 7200 Å.

NSKIES Keyword --- The value field shall contain an integer, which shows the number of sky fiber in a spectrograph.

SKYCHI2 Keyword --- The value field shall contain a real floating-point, which gives the mean chi-square of sky-subtraction. In the process of LAMOST spectra reduction, super sky is obtained by spline fitting m sky spectra. And thus, the chi-square between the super sky and each sky spectra in an exposure, and the average chi-square of m sky spectra can also be able to obtain. Assuming n times exposures, there will be 2n average chi-square because of n blue spectra and n red spectra, and this keyword will be evaluated by calculating the mean value of these 2n average chi-squares.

SCHI2MIN Keyword --- The value field shall contain a real floating-point, which gives the minimum chi-square of sky-subtraction. As mentioned above, there will be 2n average chi-squares assuming n time exposures, and this keyword will be the minimum of these chi-squares.

SCHI2MAX Keyword --- The value field shall contain a real floating-point, which gives the maximum chi-square of sky-subtraction. As mentioned above, there will be 2n average chi-squares assuming n time exposures, this keyword will be the maximum of these chi-squares.

NSTD Keyword --- The value field shall contain a non-negative integer, which shows the number of flux standard stars with good spectra quality.

FSTAR Keyword --- The value field shall contain a character string giving the fiber identity numbers of flux standard stars, which are separated by the symbol “-”. It should be noted that the fiber identity number of each flux standard star starts from zero.

FCBY Keyword --- The value field shall contain a character string giving the selection methods of flux standard stars, which include auto, manual and catalog. Auto represents the standard stars are selected by the LAMOST reduction pipeline, manual means they are picked out by experienced staffs, and catalog indicates the standard stars are provided by the input catalog.

HELIO Keyword --- The value of this keyword shall be boolean, which represents whether or not to perform the heliocentric correction.

HELIO_RV Keyword --- The value field shall contain a real floating-point, which gives the radial velocity used to carry out the heliocentric correction.

VACUUM Keyword --- The value of this keyword shall be boolean, which represents whether or not the LAMOST spectra is converted to vacuum wavelength.

NWORDER Keyword --- The value of this keyword shall contain an integer, which gives number of linear-log10 coefficients.

WFITTYPE Keyword --- The value field shall contain a character string giving linear-log10 dispersion.

COEFF0 Keyword --- The value field shall contain a real floating-point number, which provides central wavelength (log10) of first pixel.

COEFF1 Keyword --- The value field shall contain a real floating-point number giving log10 dispersion per pixel.

WAT0_001 Keyword --- The value field contains a character string.

WAT1_001 Keyword --- The value field contains a character string.

CRVAL1 Keyword --- The value field shall contain a real floating-point number, which gives the coordinate value of the reference pixel provided by the CRPIX1 keyword [7].

CD1_1 Keyword --- The value field shall contain a real floating-point giving the dispersion of per pixel.

CRPIX1 Keyword --- The value of this keyword shall contain an integer, which sets the reference pixel location on pixel axis [7].

CTYPE1 Keyword --- The value field shall contain a character string, which will have the value “LINEAR” to define the wavelength axes to be linear [8].

DC-FLAG Keyword --- The value of this keyword shall be boolean, a value of 0 defines a linear sampling of the dispersion and a value of 1 defines a logarithmic sampling of the dispersion [8].

2.3.1.8 Spectra Analysis Results Keyword

VERSPIPE= 'v2.9.8  '           / Version of Pipeline
CLASS   = 'STAR    '           / Class of object
SUBCLASS= 'M0      '           / Subclass of object
Z       =          -0.00019311 / Redshift of object
Z_ERR   =           0.00001923 / Redshift error of object
ZFLAG   = 'PIPILINE'           / Which method computes the redshift
SNRU    =                 0.66 / SNR of u filter
SNRG    =                13.32 / SNR of g filter
SNRR    =                36.14 / SNR of r filter
SNRI    =                78.57 / SNR of i filter
SNRZ    =                63.93 / SNR of z filter

VERSPIPE Keyword --- The value field shall contain a character string constant, which provides the version of LAMOST pipelines used to spectra processing and analysis. In this data release, the value of VERSPIPE is “v2.9.8”. It should be noted that, “v2.9” is the version of spectra reduction pipeline, “v8” is the version of spectra analysis pipeline, and “v2.9.8” combines these two versions together.

CLASS Keyword --- The value field shall contain a character string providing the classification result determined by the LAMOST spectra analysis pipeline, which includes “STAR”, “GALAXY”, or“QSO”.

SUBCLASS Keyword --- The value field shall contain a character string, which gives a more detailed spectral type for each star.

Z Keyword --- The value field shall contain a real floating-point number providing redshift for a target, which is determined mainly by the LAMOST spectra analysis pipeline. For the case that redshift is unable to calculate by the pipeline, it will be manually determined through measuring the shifts of some spectral line centers. If the quality of a spectrum is poor, its redshift is artificially set to -9999.

Z_ERR Keyword --- The value field shall contain a real floating-point number, which gives redshift error of a target. 

ZFLAG Keyword --- The value field shall contain three possible methods to compute the Z value: “PIPELINE”, “EYE-CHECK”, and “LASP”.

SNRU, SNRG, SNRR, SNRI and SNRZ Keywords --- The value fields of these five keywords shall contain five real floating-point numbers, which give the signal to noise ratios (S/Ns) of u, g, r, i and z bands. Using the center wavelength and bandwidth, we can obtain the wavelength range of each SDSS band, and then the S/N in each band is the median value of each pixel S/N in this band. However, it is possible that not all pixel is valid to calculate S/N. Thus, the S/N is artificially set as -9999 when the number of valid pixels used to estimate S/N is less than half of the total pixel number in each band.

2.4 Extension 1

2.4.1 Keywords

XTENSION= 'BINTABLE'           /Binary table written by MWRFITS v1.11b
BITPIX  =                    8 /Required value
NAXIS   =                    2 /Required value
NAXIS1  =                73920 /Number of bytes per row
NAXIS2  =                    1 /Number of rows
PCOUNT  =                    0 /Normally 0 (no varying arrays)
GCOUNT  =                    1 /Required value
TFIELDS =                    5 /Number of columns in table
EXTNAME = 'COADD   '    / The extension name
TTYPE1  = 'FLUX    '           /
TTYPE2  = 'IVAR    '           /
TTYPE3  = 'WAVELENGTH'         /
TTYPE4  = 'ANDMASK '           /
TTYPE5  = 'ORMASK  '           /
TTYPE6  = '  '           /
TFORM1  = '3696E   '           /
TFORM2  = '3696E   '           /
TFORM3  = '3696E   '           /
TFORM4  = '3696J   '           /
TFORM5  = '3696J   '           /
TFORM6  = '   '           /

XTENSION Keyword --- The value field shall contain a character string giving the name of the extension type. This keyword is mandatory for an extension header and must not appear in the primary header. 

BITPIX Keyword --- The value field shall contain an integer, and it shall specify the number of bits that represent a data value. A value of -32 represents IEEE single precision floating point.

NAXIS Keyword --- The value field shall contain a non-negative integer no greater than 999, representing the number of axes in the associated data array. A value of zero signifies that no data follow the header in the HDU.

NAXIS1 and NAXIS2 Keywords --- The value field of these two indexed keywords shall contain a non-negative integer, representing the number of elements along axis n of a data array. NAXIS2 is the row number of extension 1, and NAXIS1 is the byte number of each row.

PCOUNT Keyword --- The value field shall contain an integer that shall be used in any way appropriate to define the data structure. In IMAGE and TABLE extensions this keyword must have the value 0; in BINTABLE extensions, it is used to specify the number of bytes that follow the main data table in the supplemental data area called the heap.

GCOUNT Keyword --- The value field shall contain an integer that shall be used in any way appropriate to define the data structure. This keyword must have the value 1 in the IMAGE, TABLE and BINTABLE standard extensions.

TFIELDS Keyword --- The value field shall contain a non-negative integer representing the number of fields in each row. The maximum permissible value is 999.

EXTNAME Keyword --- This keyword contains a character string to be used to distinguish among different extensions of the same type in A FITS file. Within this context, the primary array should be considered as equivalent to an IMAGE extension.

TTYPE1-n Keywords --- The value field for this indexed keyword shall contain a character string giving the name of field n.

TFORM1-n Keywords --- The value field of this indexed keyword shall contain a character string describing the format in which field n is encoded.

2.4.2 Data Array

The data array of extension 1 has six columns, and table 3 explains the data in each column.

 

Table 3: Data array of Extension 1

Column Number

Data

Type

6

Normalized Flux

float

5

Ormask

float

4

Andmask

float

3

Wavelength

float

2

Inverse Variance

float

1

Flux

float

The first column is flux, the second column stores the “inverse variance” (one over sigma-squared, and sigma is the uncertainty), which can be used to estimate S/N of each pixel (S/N = flux * (inverse variance) ^ 0.5), and the third column is wavelength in unit of angstrom. The “andmask” in the fourth column is a decimal integer determined by a six-bit binary number shown in table 4, which represents six situations respectively as listed in table 5, and the associated bit of “andmask” will be set to 1 if the case always appears in each exposure. Like “andmask”, the “ormask” in fifth column is also a decimal integer determined by a six-bit binary number. The difference is that each bit of “ormask” will be set to 1 if the related case happens in any exposure.

 

Table 4: Six bits of “Andmask” and “Ormask”

6

5

4

3

2

1

 

Table 5: The significance of six bits of “Andmask” and “Ormask”

Bit

Keyword

Comments

1

BADCCD

bad pixel on CCD

2

BADPROFILE

bad profile in extraction

3

NOSKY

no sky information at this wavelength

4

BRIGHTSKY

sky level too high

5

BADCENTER

fiber trace out of the CCD

6

NODATA

no good data

For a spectrum, if you want to check which case in table 5 has happened in the spectrum reduction process, you can firstly convert the decimal “Andmask” and “Ormask” to a six-bit binary number. Then, a case must has happened in each exposure if associated bit is 1 in binary “Andmask”, and a case must has happened at least one time if associated bit is 1 in binary “Ormask”.


For a spectrum with atmospheric parameters, the sixth column in Table 3 is the normalized flux at each wavelength. For a spectrum without atmospheric parameters, the normalized spectrum was not calculated, and the normalized flux at each wavelength in the sixth column was artificially set as “-9999”. The continua of spectra with atmospheric parameters were calculated before the normalization, and the continuum calculation refers to the continuum of the best matching template, which has been prepared for each template before, and can be used directly after template matching[9]. It should be noted that the wavelength range of the normalized spectrum is from 3800 Å to 8900 Å, which is shorter than that of the original spectrum ([3700 Å, 9000 Å]), and the bluest and reddest end were removed to reduce the effect of the noise. At wavelengths outside the normalized spectrum, the fluxes were artificially set to 1.

Section 3. Catalog

In this section, we introduce 11 LAMOST catalogs published in this data release, which can be available from the website of http://www.lamost.org/dr8/v2.0/catalogue. They are the LAMOST LRS General Catalog, the LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars, the LAMOST LRS Line-Index Catalog of A Type Stars, the LAMOST LRS Catalog of gM, dM, and sdM stars, the LAMOST LRS Multiple Epoch Catalog, the LAMOST LRS Observed Plate Information Catalog, the LAMOST LRS Input Catalog, LAMOST LRS Catalog of Cataclysmic Variable Stars, LAMOST LRS Catalog of White Dwarf Stars, the LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies, and the LAMOST LRS Catalog of Emission Line Features of QSOs, respectively.

LAMOST targets were cross-matched with Gaia DR3 catalog, and their Gaia source identifiers, i.e., the “source_id” fields, and Gaia G magnitudes, i.e., the “phot_g_mean_magnitude” fields, are included in eight LAMOST LRS catalogs except the LAMOST LRS Observed Plate Information Catalog, the LAMOST LRS Multiple Epoch Catalog and the LAMOST LRS Input Catalog. 

Here, it should note that, the LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars, the LAMOST LRS Line-Index Catalog of A Type Stars, the LAMOST LRS Catalog of gM, dM, and sdM stars, LAMOST LRS Catalog of Cataclysmic Variable Stars, LAMOST LRS Catalog of White Dwarf Stars, the LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies, and the LAMOST LRS QSO Catalo are all subsets of the LAMOST LRS General Catalog. The following table 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and 16 separately show all fields of the 11 catalogs, and provide the comment for each field. Most fields in these tables are explained in detail in sub-section 2.2.1, and we only introduce the fields, which are not introduced above.

3.1 LAMOST LRS General Catalog

In this sub-section, we present the LAMOST LRS General Catalog, which includes objects obtained from LAMOST pilot survey and the regular survey of the first eight years. For galaxy, QSO and M type stars, all of them are in the catalog. But for other type targets, we published spectra with r band S/Ns larger than 2, or g band S/Ns larger than 5, or i band S/Ns larger than 5.

We totally published 10,633,515 spectra in this table, including 10,336,752 stellar spectra, 224,702 galaxy spectra, and 72,061 quasar spectra. In addition, there are 7,140,462 spectra with g band S/Ns larger than 10, 9,481,846 spectra with i band S/Ns larger than 10, and 7,060,550 spectra with g band S/Ns larger than 10 and i band S/Ns larger than 10.

All parameters of this catalog are listed in table 6, and most majorities of them are explained in section 2.2.1 in detail. In order to prevent saturation, we artificially add offsets to the equatorial coordinates from input catalog for a fraction of luminous stars during observation. Thus, we add four new fields in catalogs except the LAMOST LRS Observed Plate Information Catalog and the LAMOST LRS Multiple Epoch Catalog, and they are “ra_obs”, “dec_obs”, “offsets” and “offsets_v” respectively. The fields “ra_obs” and “dec_obs” are fiber pointing right ascension and declination during observation, and the fields “ra” and “dec” are the equatorial coordinates from the input catalog. The field “offsets” represents whether there is a fiber offset during observation, and the field “offsets_v” gives the offset value of equatorial coordinator in the input catalog if the “offsets” field is true. Note that, “offsets” and “offsets_v” in catalogs are the same as “offset” and “offset_v” in FITS header. Since “offset” is a commonly used database keyword, it should be avoided to use in catalogs. The fields “z” and “z_err” are redshift and uncertainty respectively, which were given by the LAMOST 1D pipeline, and they are set to -9999 if the redshift is unable to be estimated. Besides, the “fibermask” field is the same as the “FIBERMAS” field in the “Primary FITS Header”, which has already detailedly described in subsection 2.2.1.4.

This table was cross-matched with the Pan-STARRS catalog using a radius of 3 arcsec on the Pan-STARRS website, and the object identifier and magnitudes of Pan-STARRS are given in this table. “ps_ID” is the object identifier of Pan-STARRS (the “objid” field), “mag_ps_g”, “mag_ps_r”, “mag_ps_i”, “mag_ps_z”, and “mag_ps_y” are the magnitudes of Pan-STARRS in g, r, i, z, and y bands.

Here, we provide two formats of the LAMOST LRS General Catalog to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 6: LAMOST LRS General Catalog

Field (unit)

Type

Comment

obsid

long integer

Unique spectra ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectral type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target”s coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

fibermask

integer

Possible fiber problems

with_norm_flux

integer

It has two values of 0 and 1, 1 represents the FITS file provides the normalized spectrum, and 0 means it does not. The normalized flux is in the data array of extension 1.


3.2 LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars

In this sub-section, we introduce the LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars. We totally published 6,684,413 spectra in this catalog, including 306,264 A type star spectra, 1,983,988 F type star spectra, 3,250,062 G type star spectra and 1,144,099 K type star spectra. 

These spectra are selected with the criterion of S/N in g band larger than 6 in dark nights, and S/N in g band larger than 15 in bright nights. All fields of this catalog are listed in table 7, the fields of “teff”, “logg”, “feh” and “rv” are the effective temperatures, surface gravities, metallicities and radial velocity, which were determined by LASP. The uncertainty of atmospheric parameters and radial velocity is affected mainly by two factors, i.e., the S/N and the best-matched chi-square. Using a sample of stars subtracting variable stars and having multiple observations, the precisions of atmospheric parameters and radial velocity for each observation and the relationship between the precisions and S/N were determined. Besides, the function relationship of the best-matched chi-square and S/N can also be obtained with another sample of stars. The “teff_err”, “logg_err”, “feh_err” and “rv_err” are uncertainties of atmospheric parameters and radial velocity, respectively, and they can be estimated by the above best-matched chi-square, S/N, and the two relationships. In addition, the fields of “alpha_m” and “alpha_m_err” are alpha element abundance and the uncertainty given by the LASP, respectively. Different from above fields, the “alpha_m” field was estimated by the method of template matching based on the MARCS synthetic spectra, and its uncertainty of “alpha_m_err” was estimated by the same method used by “teff_lasp_err”, “logg_lasp_err”, and “feh_lasp_err”. 

It should be noted that A type stars in this catalog is a subset of the LAMOST LRS Line-Index Catalog of A Type Stars, and they all have high S/N spectra. Here, we provide two formats of the LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 7: LAMOST LRS Stellar Parameter Catalog of A, F, G and K Stars

Field (unit)

Type

Comment

obsid

long integer

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectral type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber Type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target”s coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

teff (K)

float

Effective temperature obtained by the LASP

teff _err (K)

float

Effective temperature uncertainty obtained by the LASP

logg (dex)

float

Surface gravity obtained by the LASP

logg_err (dex)

float

Surface gravity uncertainty obtained by the LASP

feh(dex)

float

Metallicity obtained by the LASP

feh_err (dex)

float

Metallicity uncertainty obtained by the LASP

rv (km/s)

float

Heliocentric radial velocity obtained by the LASP

rv_err (km/s)

float

Uncertainty of heliocentric radial velocity obtained by the LASP

alpha_m (dex)

float

Alpha element abundance estimated by the LASP

alpha_m_err (dex)

float

The uncertainty of alpha_m


3.3 LAMOST LRS Line-Index Catalog of A Type Stars

In this sub-section, we introduce the LAMOST LRS Line-Index Catalog of A Type Stars, and all 755,402 A type star spectra are published in this catalog, which are also in the LAMOST LRS General Catalog. Table 8 shows all fields of this catalog, and fields before “dec” have already introduced in previous section. The fields of “kp6”, “kp12”, “kp18”, “halpha12”, “halpha24”, “halpha48”, “halpha70”, “hbeta12”, “hbeta24”, “hbeta48”, “hbeta60”, “hgamma12”, “hgamma24”, “hgamma48”, “hgamma54”, “hdelta12”, “hdelta24”, “hdelta48”, “hdelta64”, “paschen13”, “paschen142” and “paschen242” are line indices of Ca II K, Halpha, Hbeta, Hgamma, Hdelta, and Paschen lines respectively, and the numbers in their names are the used band widths in the unit of angstrom. It should be noted that the three Paschen line indices use the local continua at 8467.5 Å, 8598.0 Å, and 8751.0 Å respectively. Besides, the fields of “halpha_d02”, “hbeta_d02”, “hgama_d02”, and “hdelta_d02” are the widths at 20% below the local continua of four BALMER lines. If these line indices and line widths were not available, they were set to -9999. 

Here, we provide two formats of the LAMOST LRS Line-Index Catalog of A Type Stars to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 8: LAMOST LRS Line-Index Catalog of A Type Stars

Field (unit)

Type

Comment

obsid

long integer

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Stellar Class

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target”s coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

kp12 (Å)

float

Ca II K line index with band widths of 12 Å

kp18 (Å)

float

Ca II K line index with band widths of 18 Å

kp6 (Å)

float

Ca II K line index with band widths of 6 Å

hdelta12 (Å)

float

Hdelta line Index with band widths of 12 Å

hdelta24 (Å)

float

Hdelta line Index with band widths of 24 Å

hdelta48 (Å)

float

Hdelta line Index with band widths of 48 Å

hdelta64 (Å)

float

Hdelta line Index with band widths of 64 Å

hgamma12 (Å)

float

Hgamma line Index with band widths of 12 Å

hgamma24 (Å)

float

Hgamma line Index with band widths of 24 Å

hgamma48 (Å)

float

Hgamma line Index with band widths of 48 Å

hgamma54 (Å)

float

Hgamma line Index with band widths of 54 Å

hbeta12 (Å)

float

Hbeta line Index with band widths of 12 Å

hbeta24 (Å)

float

Hbeta line Index with band widths of 24 Å

hbeta48 (Å)

float

Hbeta line Index with band widths of 48 Å

hbeta60 (Å)

float

Hbeta line Index with band widths of 60 Å

Halpha12 (Å)

float

Halpha line Index with band widths of 12 Å

Halpha24 (Å)

float

Halpha line Index with band widths of 24 Å

halpha48 (Å)

float

Halpha line Index with band widths of 48 Å

halpha70 (Å)

float

Halpha line Index with band widths of 70 Å

paschen13 (Å)

float

Paschen line index from local continuum at 8467.5 with band widths of 13.0

paschen142 (Å)

float

Paschen line index from local continuum at 8598.0 with band widths of 42.0

paschen242 (Å)

float

Paschen line index from local continuum at 8751.0 with band widths of 42.0

halpha_d02 (Å)

float

Width at 20% below the local continuum of Halpha line

hbeta_d02 (Å)

float

Width at 20% below the local continuum of Hbeta line

hgama_d02 (Å)

float

Width at 20% below the local continuum of Hgama line

hdelta_d02 (Å)

float

Width at 20% below the local continuum of Hdelta line


3.4 LAMOST LRS Catalog of gM, dM, and sdM stars

In this sub-section, we introduce the LAMOST LRS Catalog of gM, dM, and sdM stars, which includes 41,833 M giant spectra, 709,596 M dwarf spectra, and 3,973 M sub-dwarf spectra. 

The fields of “teff”, “logg”, and “m_h” in table 9 are effective temperatures, surface gravities, and metallicities for M type stars, which were determined by the minimum chi-squre estimation mentioned in Du B. et al. (2021) [10], and their errors of “teff_err”, “logg_err”, and “m_h_err” were estimated with the method that LASP used. Here, the BT-Settl CIFIST2011 spectra[11-12] were used as templates to estimate “teff”, “logg”, and “m_h”. The “ewha” and “ewha_err” fields are equivalent width (EW) of Halpha line and its error. The fields of “tio1”, “tio1_err”, “tio2”, “tio2_err”, “tio3”, “tio3_err”, “tio4”, “tio4_err”, “tio5”, “tio5_err”, “cah1”, “cah1_err”, “cah2”, “cah2_err”, “cah3”, “cah3_err”, “caoh”, “caoh_err”, and “na” are TiO, CaH, CaOH, and Na spectral line indices and their errors. Besides, a metallicity sensitive parameter of “zeta”, its error of “zeta_err”, and a magnetic activity flag of “type” were also provided in this catalog. The value of “type” includes 1 and 0, where 1 represents a M star has magnetic activity, and 0 means it does not have magnetic activity. Previous EW spectral line indices, “zeta”, “type”, and their errors were all given by the HAMMER software, and they were set to -9999 if they were unable to be determined. In addition, “z” and “z_err” are redshift and uncertainty separately, and they were estimated by the LAMOST 1D pipeline. 

Here, we provide two formats of the LAMOST LRS Catalog of gM, dM, and sdM stars to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

Table 9: LAMOST LRS Catalog of gM, dM, and sdM stars

Field (unit)

Type

Comment

obsid

long integer

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectra type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target”s coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

teff (K)

float

Effective temperature obtained by the minimum chi-squre estimation

teff _err (K)

float

Effective temperature uncertainty estimated with the method LASP used

logg (dex)

float

Surface gravity obtained by the minimum chi-squre estimation

logg_err (dex)

float

Surface gravity uncertainty estimated with the method LASP used

m_h (dex)

float

Metallicity obtained by the minimum chi-squre estimation

m_h_err (dex)

float

Metallicity uncertainty estimated with the method LASP used

ewha (Å)

float

EW of Halpha line

ewha_err (Å)

float

EW uncertainty of Halpha line

tio5 (Å)

float

Spectral indice of TiO5

cah2 (Å)

float

Spectral indice of CaH2

cah3 (Å)

float

Spectral indice of CaH3

tio1 (Å)

float

Spectral indice of TiO1

tio2 (Å)

float

Spectral indice of TiO2

tio3 (Å)

float

Spectral indice of TiO3

tio4 (Å)

float

Spectral indice of TiO4

cah1 (Å)

float

Spectral indice of CaH1

caoh (Å)

float

Spectral indice of CaOH

tio5_err (Å)

float

Spectral indice Error of TiO5

cah2_err (Å)

float

Spectral indice Error of CaH2

cah3_err (Å)

float

Spectral indice Error of CaH3

tio1_err (Å)

float

Spectral indice Error of TiO1

tio2_err (Å)

float

Spectral indice Error of TiO2

tio3_err (Å)

float

Spectral indice Error of TiO3

tio4_err (Å)

float

Spectral indice Error of TiO4

cah1_err (Å)

float

Spectral indice Error of CaH1

caoh_err (Å)

float

Spectral indice Error of CaOH

zeta

float

Metallicity sensitive parameter

zeta_err

float

Error of metallicity sensitive parameter

type

integer

Magnetic activity

na (Å)

float

Line indice of Na line


3.5 LAMOST LRS Multiple Epoch Catalog

In this sub-section, we introduce the LAMOST LRS Multiple Epoch Catalog, and each column of this catalog represents a source with multiple observations. There are in total of 1,963,484 targets in this catalog, and there are 13 parameters provided for each source. The equator coordinates used to calculate the source identifier were mainly from the Gaia or Pan-STARRS survey. For a few sources without equator coordinates of Gaia or Pan-STARRS, the source identifiers were estimated with the equator coordinates in LAMOST input catalog.

In this catalog, “uid” is the unique LAMOST source identifier, which was calculated by the Hierarchical Triangular Mesh (HTM) algorithm [13] (the “HMpTy” package), and “ura” and “udec” are the equator coordinates to calculate “uid”. “gp_id” provides the corresponding source identifier in the Pan-STARRS, Gaia, or LAMOST, which depends on “ura” and “udec” of which survey were used to calculate “uid”.

The “obs_number”, “obsid_list”, “midmjm_list”, “z_list”, “teff_list”, “logg_list”, “feh_list”, and “rv_list” fields provide the observation number, unique spectrum ID list, modified Julian minute list at the middle time of multiple exposures in one-night, red shift list , effective temperature list, surface gravity list, metallicity list and radial velocity list, respectively. Because these targets were observed at multiple nights, their “obs_number” are all greater than 1, and their unique spectrum ID, modified Julian minute of the middle time of multiple exposures, red shift, effective temperature, surface gravity, metallicity, and radial velocity of each observation are separated by the sign of  “-”.  It should be noted that, you can use each obsid in the “obsid_list” field to cross-match with other LAMOST LRS catalogs.

By cross-matching with 11 SOS tables [14] of Gaia DR3, the variability types were obtained for variable sources in this table, and the “gaia_vari_type_sos” provides their variability types.

It should be noted that, you can use each obsid in the “obsid_list” field to cross-match with other LAMOST LRS catalogs. Here, we provide two formats of the LAMOST LRS Multiple Epoch Catalog to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 10: LAMOST LRS Multiple Epoch Catalog

Field (unit)

Type

Comment

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

ura (degree)

float

Right ascension used to calculate “uid”, and it may be from Gaia, Pan-STARRS, or LAMOST.

udec (degree)

float

Declination used to calculate “uid”, and it may be from Gaia, Pan-STARRS, or LAMOST.

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

obs_number

int

Observation plan numbers for each target with multiple epoch observations

obsid_list

char

The “obsid” list

midmjm_list

char

Modified Julian minute list of the middle time of multiple exposure

z_list

char

Red shift list

teff_list

char

Effective temperature list

log_list

char

Surface gravity list

feh_list

char

Metallicity list

rv_list

char

Radial velocity list

gaia_vari_type_sos

char

Variability types obtained by cross-matching with 11 Specific Object Studies (SOS) tables of Gaia DR3

 

3.6 LAMOST LRS Observed Plate Information Catalog

In this sub-section, we introduce the LAMOST LRS Observed Plate Information Catalog, which includes 9 parameters for all 5,207 published plates, and the “obsdate” and “planid” fields in this table have already been introduced. The fields of “ra” and “dec” are right ascension and declination of center star of each plate, and the field “mag” is the magnitude of center star. The field of “seeing” is the dome seeing of the first exposure, and the field of “exptime” is the total exposure time of n time exposures. Besides, the “lmjm” field is the local modified Julian minute at the start time of each plate, and the “pid” is the unique ID of each plate.

Here, we provide two formats of the LAMOST LRS Observed Plate Information Catalog to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 11: LAMOST LRS Observed Plate Information Catalog

Field (unit)

Type

Comment

pid

integer

Plate ID

obsdate

float

Target observation date

planid

char

Plan name

ra (degree)

float

Right ascension of center star

dec (degree)

float

Declination of center star

mag (mag)

float

Magnitude of center star

seeing

float

Seeing of the first exposure

exptime (second)

float

The total exposure time of n time exposures

lmjm

Integer

Local modified Julian minute at the start time of each plate

 

3.7 LAMOST LRS Input Catalog

In this sub-section, we introduce the LAMOST LRS Input Catalog, which includes 27 parameters for 13,954,016 targets. There are 12 fields not included in previous tables, and they are the “unitid”, “epoch”, “tname”, “objtype”, “magtype”, “mag0”, “mag1”, “mag2”, “mag3”, “mag4”, “mag5”, “mag6” and “mag7” fields respectively. The “unitid” field is the ID of 4000 fiber units, “tname” is the unique ID of this catalog for each target, the value of “epoch” is “J2000”, “objtype” is the object class provided by the organizations or individuals who submitted the input catalogs, “magtype”gives the magnitude bands, and “mag0”-“mag7” is the magnitudes of the bands referred to “magtype”, which were given by the person or organization submitting the observation plan.

Here, we provide two formats of the LAMOST LRS Input Catalog to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 12: LAMOST LRS Input Catalog

Field (unit)

Type

Comment

obsid

long integer

unique spectrum ID

obsdate

float

Target observation date

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

unitid

char

ID of 4000 fiber units

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

objtype

char

Object type

magtype

char

Target magnitude type

mag1 (mag)

float

Associated magnitude 1

mag2 (mag)

float

Associated magnitude 2

mag3 (mag)

float

Associated magnitude 3

mag4 (mag)

float

Associated magnitude 4

mag5 (mag)

float

Associated magnitude 5

mag6 (mag)

float

Associated magnitude 6

mag7 (mag)

float

Associated magnitude 7

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target [Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target”s coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

epoch

char

J2000

tname

char

Unique ID for each targets in this catalog

 

3.8 LAMOST LRS Catalog of Cataclysmic Variable Stars

In this sub-section, we introduce the LAMOST LRS Catalog of Cataclysmic Variable Stars. 455 spectra of cataclysmic variable stars are included in this table, and they were found by the Bagging TopPush algorithm. There are 39 fields in this catalog, 37 of them are also included in the LAMOST LRS General Catalog of sub-section 3.1. The two fields not in sub-section 3.1 are “class_liter” and “period_liter”, which are the sub-types and orbital periods of cataclysmic variable stars in the literature, and the description of “class_liter” can refer to http://www.sai.msu.su/gcvs/gcvs/vartype.htm. 

Here, we provide two formats of the LAMOST LRS Catalog of Cataclysmic Variable Stars to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

Table 13: LAMOST LRS Catalog of Cataclysmic Variable stars

Field (unit)

Type

Comment

obsid

long integer

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectra type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target's coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

class_liter

char

Sub-types of cataclysmic variable stars, the description can refer to  http://www.sai.msu.su/gcvs/gcvs/vartype.htm.

period_liter (day)

float

Orbital periods of cataclysmic variable stars


3.9 LAMOST LRS Catalog of White Dwarf Stars

In this sub-section, we introduce the LAMOST LRS Catalog of White Dwarf Stars, and this catalog includes 15,601 spectra of white dwarf stars. There are 42 fields in this catalog, 37 of them are also included in the LAMOST LRS General Catalog of sub-section 3.1. The five fields not in sub-section 3.1 are “wd_subclass”, “teff”, “teff_err”, “logg” and “logg_err”, which are the spectral sub-types, effective temperatures, and surface gravities of white dwarf stars. The “wd_subclass” field was determined by the machine learning method of ”LASSO+SVM” introduced in Kong, X. et al. (2018) [15], and the other four parameters were determined by the least-square fitting algorithm.

Here, we thank J.K. Zhao and D. Koester for providing the parameter templates of DA and DB stars. These models were made by D. Koester (2010) [16] ranging from 5 000 K to 80 000 K and 7.0 to 9.5 for the effective temperature and surface gravity respectively. We provide two formats of the LAMOST LRS Catalog of White Dwarf Stars to download, which include a FITS table and a CSV table, and can be available from http://www.lamost.org/dr8/v2.0/catalogue.

 

Table 14: LAMOST LRS Catalog of White Dwarf Stars

Field (unit)

Type

Comment

obsid

long integer   

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectra type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target's coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

wd_subclass

char

Spectral sub-types of white dwarf stars

teff (K)

float

Effective temperature obtained by the least square fit

teff_err (K)

float

Effective temperature uncertainty obtained by the least-square fitting algorithm

logg (K)

float

Surface gravity obtained by the least square fit

logg_err (K)

float

Surface gravity uncertainty obtained by the least-square fitting algorithm


3.10 LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies

In this sub-section, we introduce the LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies. This table includes 59 parameters for 21,719 galaxy spectra, and the first 37 parameters are also in the LAMOST LRS General Catalog. The other 22 parameters are the total integrated fluxes (“*_flux”, “*” is the name of the emission line) and EWs (“*_ew”, “*” is the name of the emission line) of eight emission lines, age (“age_lw” and “age_mw”), metallicity (“metal_lw” and “metal_mw”), stellar velocity dispersion, and its error, respectively.

At first, the fluxes of galaxy spectra are calibrated using the SDSS photometry data [17]. Then, the total integrated fluxes and EWs of eight emission lines are calculated by referring to the DAP software algorithm [18], the light and mass weighted ages (“age_lw” and “age_mw”) and metallicities (“metal_lw” and “metal_mw”) are obtained by the FIREFLY code [19], and the stellar velocity dispersion and its error are estimated by the PPXF package [20].

Here, we provide two formats of the LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

Table 15:LAMOST LRS Catalog of Stellar Population Synthesis of Galaxies

Field (unit)

Type

Comment

obsid

long  integer   

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectra type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target's coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

hbeta_flux (erg/s/cm2)

float

Total integrated flux in the Hbeta emission line

hbeta_ew (Å)

float

EW of the Hbeta emission line

oiii_4960_flux (erg/s/cm2)

float

Total integrated flux in the [O III] 4960 emission line

oiii_4960_ew (Å)

float

EW of the [O III] 4960 emission line

oiii_5008_flux (erg/s/cm2)

float

Total integrated flux in the [O III] 5008 emission line

oiii_5008_ew (Å)

float

EW of the [O III] 5008 emission line

nii_6550_flux (erg/s/cm2)

float

Total integrated flux in the [N II] 6550 emission line

nii_6550_ew (Å)

float

EW of the [N II] 6550 emission line

halpha_flux (erg/s/cm2)

float

Total integrated flux in the Halpha emission line

halpha_ew (Å)

float

EW of the Halpha emission line

nii_6585_flux (erg/s/cm2)

float

Total integrated flux in the [N II] 6585 emission line

nii_6585_ew (Å)

float

EW of the [N II] 6585 emission line

sii_6718_flux (erg/s/cm2)

float

Total integrated flux in the [S II] 6718 emission line

sii_6718_ew (Å)

float

EW of the [S II] 6718 emission line

sii_6733_flux (erg/s/cm2)

float

Total integrated flux in the [S II] 6733 emission line

sii_6733_ew (Å)

float

EW of the [S II] 6733 emission line

age_lw (log(age(Gyr)))

float

Age (Light-weighted)

age_mw (log(age(Gyr)))

float

Age (Mass-weighted)

metal_lw ([Z/H])

float

Metallicity (Light-weighted)

metal_mw ([Z/H])

float

Metallicity (Mass-weighted)

vsig (km/s)

float

Stellar velocity dispersion

vsig_err (km/s)

float

The uncertainty of Stellar velocity dispersion

 

3.11 LAMOST LRS Catalog of Emission Line Features of QSOs

In this sub-section, we introduce the LAMOST LRS Catalog of Emission Line Features of QSOs. This table includes 184 parameters for 17,824 QSO spectra, and the first 37 parameters (before “sn_ratio_conti”) are also in the LAMOST LRS General Catalog. The other 147 parameters are the measurement results of six groups of emission lines in QSO spectra.

The fluxes of QSO spectra are calibrated using the SDSS photometry data [21], and emission lines are divided into six groups to be measured: (1) The broad component and narrow component of Lyman alpha (Lya); (2) The broad component and narrow component of C IV; (3) The broad component and narrow component of C III; (4) A broad component and two narrow components of Mg II; (5) The broad component and narrow component of Hbeta, [O III] 4959, and [O III] 5007; (6) Two broad components and two narrow components of Halpha, [N II] 6549, [N II] 6583, [S II] 6718, and [S II] 6732. 

The PyQSOfit code [21] is used to measure the above six groups of emission lines in LAMOST QSO spectra. From “sn_ratio_conti” to “l5100”, they are parameters obtained by fitting the continua of QSO spectra, and the fields from “line_name_1” to “ndof_6” are the name of each group of emission lines, the fitting status indicating whether the fitting is successful, the minimum chi-square value, the reduced chi-square value, and the degree of freedom, respectively. From “lya_br_1_peak_flux” to “sii6732_1_sigma”, the peak wavelength, peak flux, and line dispersion of each group emission lines are given, and full width at half maximum (FWHM), line dispersion, EW, peak wavelength, and integrated flux of Lya (including the broad and narrow components), C IV (including the broad and narrow components), C III (including the broad and narrow components), Mg II (including the broad and narrow components), Hbeta (including the broad and narrow components, but excluding [O III] 4959 and [O III] 5007), and Halpha (including the broad and narrow components, but excluding [N II] 6549, [N II] 6583, [S II] 6718 and [S II]6732) are given after the “lya_fwhm” field.

Here, we provide two formats of the LAMOST LRS Catalog of Emission Line Features of QSOs to download, which include a FITS table and a CSV table, and they can be available from http://www.lamost.org/dr8/v2.0/catalogue.

Table 16:LAMOST LRS Catalog of Emission Line Features of QSOs

Field (unit)

Type

Comment

obsid

long integer 

unique spectrum ID

uid

char

Unique source identifier calculated with the “ura” and “udec” in table 10

gp_id

char

For each LAMOST source, the equatorial coordinates (“ura” and “udec” in table 10) used to calculate “uid” were from which survey (Pan-STARRS, Gaia or LAMOST), “gp_id” gives the corresponding source identifier in that survey.

designation

char

Target designation

obsdate

char

Target observation date

lmjd

char

Local modified Julian day

mjd

char

Modified Julian day

planid

char

Plan name

spid

integer

Spectrograph ID

fiberid

integer

Fiber ID

ra_obs (degree)

float

Fiber pointing right ascension

dec_obs (degree)

float

Fiber pointing declination

snru

float

S/N of u filter

snrg

float

S/N of g filter

snrr

float

S/N of r filter

snri

float

S/N of i filter

snrz

float

S/N of z filter

class

char

Spectra type

subclass

char

Stellar spectral type

z

float

Redshift

z_err

float

Redshift uncertainty

ps_ID

long integer

The objID in the Pan-STARRS catalog

mag_ps_g (mag)

float

Pan-STARRS g band magnitude

mag_ps_r (mag)

float

Pan-STARRS r band magnitude

mag_ps_i (mag)

float

Pan-STARRS i band magnitude

mag_ps_z (mag)

float

Pan-STARRS z band magnitude

mag_ps_y (mag)

float

Pan-STARRS y band magnitude

gaia_source_id

char

The “source_id” field of Gaia DR3 catalog

gaia_g_mean_mag (mag)

float

The “phot_g_mean_magnitude” field of Gaia DR3 catalog

tsource

char

Organization or person who submit input catalog

fibertype

char

Fiber type of target

[Obj, Sky, F-std, Unused, PosErr, Dead]

tfrom

char

Input catalog submitted by an organization or a person determined by the tsource

tcomment

char

Target ID from SDSS, UCAC4, PANSTAR and other catalogues

offsets

bool

Whether there is a fiber offset during observation

offsets_v (arcsec)

float

If the “offsets” field is true, “offsets_v” gives the offset distance from the target's coordinator in input catalog

ra (degree)

float

Right ascension from input catalog

dec (degree)

float

Declination from input catalog

sn_ratio_conti

float

Continuum S/N

fe_uv_norm

float

Normalization parameter of Fe II spectrum in UV band

fe_uv_fwhm (km/s)

float

Rest-frame FWHM of Fe II spectrum in UV band

fe_uv_shift (Å)

float

Wavelength shift of Fe II spectrum in UV band

fe_op_norm

float

Normalization parameter of Fe II spectrum in optical band

fe_op_fwhm (km/s)

float

Rest-frame FWHM of Fe II spectrum in optical band

fe_op_shift (Å)

float

Wavelength shift of Fe II spectrum in optical band

pl_norm

float

Normalization parameter of AGN power law

pl_slope

float

Slope of AGN power law

balmer_norm

float

Normalization parameter of Balmer continuum

balmer_teff (K)

float

Electron temperature

balmer_tau_e

float

Optical depth at the Balmer edge of 3646 Å

poly_a

float

The coefficient of the first term of the third-order polynomial in the continuum fitting

poly_b

float

The coefficient of the quadratic term of the third-order polynomial in the continuum fitting

poly_c

float

The coefficient of the cubic term of the third-order polynomial in the continuum fitting

l1350

float

Continuum luminosity in common logarithm at rest-frame 1350 Å

l3000

float

Continuum luminosity in common logarithm at rest-frame 3000 Å

l5100

float

Continuum luminosity in common logarithm at rest-frame 5100 Å

line_name_1

char

The name of the first group of spectral lines

fitting _status_1

int

The fitting status of the first group lines, and the value larger than 0 means a success fitting. See  https://idlastro.gsfc.nasa.gov/ftp/pro/markwardt/mpfit.pro

for other values.

min_chi2_1

float

Minimal chi-square in the fitting of the first group lines

red_chi2_1

float

Reduced chi-square in the fitting of the first group lines

ndof_1

float

Degree of freedom in the fitting of the first group lines

line_name_2

char

The name of the second group of spectral lines

fitting_status_2

int

The fitting status of the second group lines, and the value larger than 0 means a success fitting. See https://idlastro.gsfc.nasa.gov/ftp/pro/markwardt/mpfit.pro for other values.

min_chi2_2

float

Minimal chi-square in the fitting of the second group lines

red_chi2_2

float

Reduced chi-square in the fitting of the second group lines

ndof_2

float

Degree of freedom in the fitting of the second group lines

line_name_3

char

The name of the first group of spectral lines

fitting_status_3

int

The fitting status of the third group lines, and the value larger than 0 means a success fitting. See https://idlastro.gsfc.nasa.gov/ftp/pro/markwardt/mpfit.pro for other values.

min_chi2_3

float

Minimal chi-square in the fitting of the third group lines

red_chi2_3

float

Reduced chi-square in the fitting of the third group lines

ndof_3

float

Degree of freedom in the fitting of the third group lines

line_name_4

char

The name of the fourth group of spectral lines

fiiting_status_4

int

The fitting status of the fourth group lines, and the value larger than 0 means a success fitting. See https://idlastro.gsfc.nasa.gov/ftp/pro/markwardt/mpfit.pro for other values.

min_chi2_4

float

Minimal chi-square in the fitting of the fourth group lines

red_chi2_4

float

Reduced chi-square in the fitting of the fourth group lines

ndof_4

float

Degree of freedom in the fitting of the fourth group lines

line_name_5

char

The name of the fifth group of spectral lines

fitting_status_5

int

The fitting status of the fifth group lines, and the value larger than 0 means a success fitting. See https://idlastro.gsfc.nasa.gov/ftp/pro/markwardt/mpfit.pro for other values.

min_chi2_5

float

Minimal chi-square in the fitting of the fifth group lines

red_chi2_5

float

Reduced chi-square in the fitting of the fifth group lines

ndof_5

float

Degree of freedom in the fitting of the fifth group lines

line_name_6

char

The name of the sixth group of spectral lines

fitting_status_6

int

The fitting status of the sixth group lines, and the value larger than 0 means a success fitting. See https://idlastro.gsfc.nasa.gov/ftp/pro/markwardt/mpfit.pro for other values.

min_chi2_6

float

Minimal chi-square in the fitting of the sixth group lines

red_chi2_6

float

Reduced chi-square in the fitting of the sixth group lines

ndof_6

float

Degree of freedom in the fitting of the sixth group lines

lya_br_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Lya broad component

lya_br_1_peak_wavelength

float

Peak wavelength in natural logarithm of Lya broad component

lya_br_1_sigma

float

Line dispersion in natural logarithm of Lya broad component 

lya_na_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Lya narrow component

lya_na_1_peak_wavelength

float

Peak wavelength in natural logarithm of Lya narrow component

lya_na_1_sigma

float

Line dispersion in natural logarithm of Lya narrow component 

civ_br_1_ peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of CIV broad component

civ_br_1_ peak_wavelength

float

Peak wavelength in natural logarithm of C IV broad component

civ_br_1_sigma

float

Line dispersion in natural logarithm of C IV broad component

civ_na_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of C IV narrow component

civ_na_1_peak_wavelength

float

Peak wavelength in natural logarithm of C IV narrow component

civ_na_1_sigma

float

Line dispersion in natural logarithm of CIV narrow component

ciii_br_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the first C III broad component

ciii_br_1_peak_wavelength

float

Peak wavelength in natural logarithm of the first C III broad component

ciii_br_1_sigma

float

Line dispersion in natural logarithm of the first C III broad component

ciii_br_2_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the second C III broad component

ciii_br_2_peak_wavelength

float

Peak wavelength in natural logarithm of the second C III broad component

ciii_br_2_sigma

float

Line dispersion in natural logarithm of the second C III broad component

ciii_na_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the first C III narrow component

ciii_na_1_peak_wavelength

float

Peak wavelength in natural logarithm of the first C III narrow component

ciii_na_1_sigma

float

Line dispersion in natural logarithm of the first C III narrow component

ciii_na_2_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the second C III narrow component

ciii_na_2_peak_wavelength

float

Peak wavelength in natural logarithm of the second C III narrow component

ciii_na_2_sigma

float

Line dispersion in natural logarithm of the second CIII narrow component

mgii_br_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Mg II broad component

mgii_br_1_peak_wavelength

float

Peak wavelength in natural logarithm of Mg II broad component

mgii_br_1_sigma

float

Line dispersion in natural logarithm of Mg II broad component

mgii_na_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the first Mg II narrow component

mgii_na_1_peak_wavelength

float

Peak wavelength in natural logarithm of the first Mg II narrow component

mgii_na_1_sigma

float

Line dispersion in natural logarithm of the first Mg II narrow component

mgii_na_2_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the second Mg II narrow component

mgii_na_2_peak_wavelength

float

Peak wavelength in natural logarithm of the second Mg II narrow component

mgii_na_2_sigma

float

Line dispersion in natural logarithm of the second Mg II narrow component

hb_br_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Hbeta broad component

hb_br_1_peak_wavelength

float

Peak wavelength in natural logarithm of Hbeta broad component

hb_br_1_sigma

float

Line dispersion in natural logarithm of Hbeta broad component

hb_na_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Hbeta narrow component

hb_na_1_peak_wavelength

float

Peak wavelength in natural logarithm of Hbeta narrow component

hb_na_1_sigma

float

Line dispersion in natural logarithm of Hbeta narrow component

oiii4959_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of [O III] 4959

oiii4959_1_peak_wavelength

float

Peak wavelength in natural logarithm of [O III] 4959

oiii4959_1_sigma

float

Line dispersion in natural logarithm of [O III] 4959

oiii5007_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of [O III] 5007

oiii5007_1_peak_wavelength

float

Peak wavelength in natural logarithm of [O III] 5007

oiii5007_1_sigma

float

Line dispersion in natural logarithm of [O III] 5007

ha_br_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the first Halpha broad component

ha_br_1_peak_wavelength

float

Peak wavelength in natural logarithm of the first Halpha broad component

ha_br_1_sigma

float

Line dispersion in natural logarithm of the first Halpha broad component

ha_br_2_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of the second Halpha broad component

ha_br_2_peak_wavelength

float

Peak wavelength in natural logarithm of the second Halpha broad component

ha_br_2_sigma

float

Line dispersion in natural logarithm of the second Halpha broad component

ha_br_3_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Halpha broad component

ha_br_3_peak_wavelength

float

Peak wavelength in natural logarithm of the third Halpha broad component

ha_br_3_sigma

float

Line dispersion in natural logarithm of the third Halpha broad component

ha_na_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of Halpha narrow component

ha_na_1_peak_wavelength

float

Peak wavelength in natural logarithm of Halpha narrow component

ha_na_1_sigma

float

Line dispersion in natural logarithm of Halpha narrow component

nii6549_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of [N II] 6549

nii6549_1_peak_wavelength

float

Peak wavelength in natural logarithm of [N II] 6549

nii6549_1_sigma

float

Line dispersion in natural logarithm of [N II] 6549

nii6585_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of [N II] 6585

nii6585_1_peak_wavelength

float

Peak wavelength in natural logarithm of [N II] 6585

nii6585_1_sigma

float

Line dispersion in natural logarithm of [N II] 6585

sii6718_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of [S II] 6718

sii6718_1_peak_wavelength

float

Peak wavelength in natural logarithm of [S II] 6718

sii6718_1_sigma

float

Line dispersion in natural logarithm of [S II] 6718

sii6732_1_peak_flux (1e-17 erg/s/cm2/Å)

float

Peak flux of [S II] 6732

sii6732_1_peak_wavelength

float

Peak wavelength in natural logarithm of [S II] 6732

sii6732_1_sigma

float

Line dispersion in natural logarithm of [S II] 6732

lya_fwhm (km/s)

float

FWHM of entire Lya

lya_ sigma (km/s)

float

Line dispersion of entire Lya

lya_ew (Å)

float

EW of entire Lya

lya_peak_wavelength (Å)

float

Peak wavelenth of entire Lya

lya_area (erg/s/cm2)

float

Integrated Flux of entire Lya

civ_fwhm (km/s)

float

FWHM of entire C IV

civ_sigma (km/s)

float

Line dispersion of entire C IV

civ_ew (Å)

float

EW of entire C IV

civ_ peak_wavelength (Å)

float

Peak wavelenth of entire C IV

civ_area (erg/s/cm2)

float

Integrated Flux of entire C IV

ciii_whm (km/s)

float

FWHM of entire C III

ciii_sigma (km/s)

float

Line dispersion of entire C III

ciii_ew (Å)

float

EW of entire C III

ciii_ peak_wavelength (Å)

float

Peak wavelenth of entire C III

ciii_area (erg/s/cm2)

float

Integrated Flux of entire C III

mgii_fwhm (km/s)

float

FWHM of entire Mg II

mgii_sigma (km/s)

float

Line dispersion of entire Mg II

mgii_ew (Å)

float

EW of entire Mg II

mgii_ peak_wavelength (Å)

float

Peak wavelenth of entire Mg II

mgii_area (erg/s/cm2)

float

Integrated Flux of entire Mg II

hb_fwhm (km/s)

float

FWHM of entire Hbeta

hb_sigma (km/s)

float

Line dispersion of entire Hbeta

hb_ew (Å)

float

EW of entire Hbeta

hb_ peak_wavelength (Å)

float

Peak wavelenth of entire Hbeta

hb_area (erg/s/cm2)

float

Integrated Flux of entire Hbeta

ha_fwhm (km/s)

float

FWHM of entire Halpha

ha_sigma (km/s)

float

Line dispersion of entire Halpha

ha_ew (Å)

float

EW of entire Halpha

ha_ peak_wavelength (Å)

float

Peak wavelenth of entire Halpha

ha_area (erg/s/cm2)

float

Integrated Flux of entire Halpha


Bibliography

1.    http://www.sdss.org/

2.    Cui, Xiangqun, Zhao, Yongheng, Chu, Yaoquan, et al. 2012, The Large Sky Area Multi-Object Spectroscopic Telescope (LAMOST), RAA, 12, 1197.

3.    Luo, A-li, Zhang, Haotong, Zhao Yongheng, et al. 2012, Data release of the LAMOST pilot survey, RAA, 12, 1243.

4.    Zhao, Gang, Zhao, Yongheng, Chu, Yaoquan, et al. 2012, LAMOST spectral survey – An overview, RAA, 12, 723.

5.    Pence, W.D., Chiappetti, L., Page, C.G., et al.  2010, Definition of the Flexible Image Transport System (FITS), version 3.0, A&A, 524, 42.

6.    http://www.skyserver.org/htm/

7.    http://adass.org/adass/proceedings/adass94/greisene.html

8.    http://iraf.net/irafdocs/specwcs.php

9.    中国科学院国家天文台,一种基于模板匹配的低分辨率很行连续谱自动拟合方法:中国,ZL 2018 1 0137582.6 [P]. 2020-10-09

10.    Du Bing, Luo Ali, Zhang Shuo, et al. 2021, RAA, 21, 202

11.    Allard, F., Homeier, D., & Freytag, B. 2011, Astronomical Society of the Pacific Conference Series, Vol. 448, Model Atmospheres From Very Low Mass Stars to Brown Dwarfs, ed. C. Johns-Krull, M. K. Browning, & A. A. West, 91

12.    Allard, F., Homeier, D., Freytag, B., & Sharp, C. M. 2012, in EAS Publications Series, Vol. 57, EAS Publications Series, ed. C. Reyl\'e, C. Charbonnel, & M. Schultheis, 3–43

13.    Kunszt, Peter Z., Szalay, Alexander S., Thakar, Aniruddha R. The Hierarchical Triangular Mesh, Mining the Sky: Proceedings of the MPA/ESO/MPE Workshop Held at Garching, Germany, July 31 - August 4, 2000, ESO ASTROPHYSICS SYMPOSIA. ISBN 3-540-42468-7. Edited by A.J. Banday, S. Zaroubi, and M. Bartelmann. Springer-Verlag, 2001, p. 631

14.    Eyer, L., Audard, M., Holl, B., et al. Gaia Data Release 3. Summary of the variability processing and analysis. 2022, arXiv:2206.06416

15.    Kong, X., Luo, A.-L., Li, X.-R., et al. 2018, Spectral Feature Extraction for DB White Dwarfs Through Machine Learning Applied to New Discoveries in the Sdss DR12 and DR14, Publications of the Astronomical Society of the Pacific, 130, 084203

16.    Koester, D. 2010, White dwarf spectra and atmosphere models, Memorie della Societa Astronomica Italiana, 81, 921

17.    Wang, L., Luo, A.L., Shen, S.Y., et al. 2018, Spectral classification and composites of galaxies in LAMOST DR4, MNRAS, 474, 1873

18.    Westfall Kyle B., Cappellari Michele Bershady, Matthew A. et al. 2019, The Data Analysis Pipeline for the SDSS-IV MaNGA IFU Galaxy Survey: Overview, AJ, 158, 231

19.    Wilkinson David M., Maraston Claudia, Goddard Daniel, et al. 2017, FIREFLY (Fitting IteRativEly For Likelihood analYsis): a full spectral fitting code, MNRAS, 472, 4297

20.    Cappellari, Michele. 2017, Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions, 466, 798

21.    Guo, H., Shen, Y., & Wang, S. 2018, Astrophysics Source Code Library. ascl:1809.008