Data Release of LAMOST Medium Resolution Spectral (MRS) Commissioning Survey

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 deg$^{2}$ in the sky. LAMOST has conducted the medium resolution spectral (MRS) commissioning survey since September 2017, and completed it on July of 2018.

After this one year survey, 4,509,135 single exposure spectra and 1,279,640 coadded spectra were finally obtained, and they were written into 640,064 FITS files. Except the data products of low resolution survey, the sixth data release (DR6) has also published medium resolution spectra and parameters online (http://dr6.lamost.org/), and the data products of MRS survey include:

  1. Spectra. - For a target, we get two spectra within an exposure, including a blue (B) and a red (R) band spectra. Generally, each object was observed several times, then we would obtain the coadded B and R band spectra by combing the single exposure spectra. Few targets, however, lack of the spectral data of either band for some reason like the wavelength calibration, and only one even no coadded spectra exists in their FITS file. For the B and R band coadded spectra, their logarithmic wavelength are [3.69172, 3.72940] and [3.79845, 3.83650], respectively.

  2. Spectroscopic Parameter Catalogs. - In this data release, four spectroscopic parameter catalogs are published, and they are the LAMOST MRS General Catalog, the LAMOST MRS Parameter Catalog, the LAMOST MRS Observed Plate Information Catalog, and the LAMOST MRS Input Catalog, respectively. In the LAMOST MRS General Catalog, 35 basic spectroscopic parameters and four radial velocity measurements are included, such as right ascension, declination, signal to noise ratio (S/N), magnitude, and so on, and they are also presented in the LAMOST MRS Parameter Catalog. The LAMOST MRS Parameter Catalog also provide atmospheric parameters (effective temperature, surface gravity, and metallicity), alpha element abundance, projected rotation velocity, radial velocity and calibrated radial velocity, and the LAMOST MRS Observed Plate Information Catalog provide nine basic parameters of each plate of MRS survey, for example, dome seeing. In addition, the LAMOST MRS Input Catalog includes 27 parameters for each target.

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

Section 2. FITS File

2.1 Designation

In this data release, 640,064 FITS files are published on-line which include 4,509,135 single exposure spectra and 1,279,640 coadded spectra, and they are named in the form of ‘med-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 , respectively.

2.2 Structure

For each of LAMOST targets, it has m (m <= n) B band and t (t <= n) R band single exposure spectra if it has n time exposures. If m and t are all larger than 0, the target has a B band and a R band coadded spectra, but no coadded spectrum is provided in the FITS file if at least one of m and n is equal to 0.

In a LAMOST median resolution (MR) FITS file, extension 0 is the primary HDU which is not followed by a primary data array, and extension 1 and 2 restore the coadded B and R band spectra, respectively. For extensions from 3 to n + 2, they save the information of m B band spectra obtained within n time exposures, and they are named as ‘B-lmjm’, where ‘lmjm’ is the local modified Julian minutes at the beginning of each exposure. For following extensions from n+3 to 2n+2, t R band spectra of n time exposures are stored, and they are called as ‘R-lmjm’.

In following section 2.3, 2.4 and 2.5, we will introduce the primary extension, extension 1 and 2, and other single exposure extensions.

2.3 Primary Extension

In this section, we describe the primary extension. Not like the low resolution FITS file, this extension of MR FITS file only has a file header, and it do not have following data array.

In the header file, we divided keywords into seven groups, and they are mandatory keywords, file information keywords, telescope parameter keywords, observation parameter keywords, spectrograph parameter keywords, weather condition keywords, and data reduction parameter keywords, respectively. We will explain keywords of each group from subsection 2.3.1 to 2.3.7.

2.3.1 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 v1.8
BITPIX  =                   -32 /
NAXIS   =                    2 /
NAXIS1  =                 3909 /
NAXIS2  =                    5 /
EXTEND  =                   T /Extensions may be present

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.

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 Number of bytes per row, and the ‘NAXIS2’ keyword indicates the row number of 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.

2.3.2 File Information Keywords

FILENAME=   'spec-57093-HD154717N140655V01_sp01-135.fits' /
OBSID   =    5935 / Unique number ID of this spectrum
AUTHOR  =  'LAMOST Pipeline'    / Who compiled the information
DATA_V  =   'LAMOST DR3'         / Data release version
EXTEN0  =   'Flux, Inverse, Wavelength, Andmask, Ormask' /
N_EXTEN =   1 / The extension number
EXTNAME =  'Flux    '           / The extension name
ORIGIN  =  'NAOC-LAMOST'        / Organization responsible for creating this file
DATE    =   '2015-12-16T10:01:21' / 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-56094-kepler05F56094_sp01-020.fits ‘ as an example, ‘56094’ is the local modified Julian day, ‘kepler05F56094’ is the plan ID, ‘sp01’ is the spectrograph ID, and ‘020’ is the Fiber ID.

OBSID Keyword --- The value field shall 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 constants ‘LAMOST DR3’, which represents the data release version.

EXTEN0 Keyword --- This keyword contains a string constant ‘Flux Inverse Subcontinuum Andmask Ormask’ explaining each row of the primary data array in a primary HDU.

N_EXTEN Keyword --- The value field shall contain an integer giving the extension number of a FITS file.

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.

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.

2.3.3 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.

2.3.4 Observation Parameter Keywords

DATE-OBS= '2017-09-28T16:43:00' / The observation median UTC
DATE-BEG= '2017-09-29T00:38:45.0' / The observation start local time
DATE-END= '2017-09-29T00:48:45.0' / The observation end local time
LMJD    =                58025 / Local Modified Julian Day
MJD     =                58024 / Modified Julian Day
PLANID  = 'HIP507401'          / Plan ID in use
RA      =            15.232672 / [deg] Right ascension of object
DEC     =             3.704588 / [deg] Declination of object
RA_OBS  =            15.232672 / [deg] Right ascension during observing
DEC_OBS =             3.704588 / [deg] Declination during observing
OFFSET  =                    F / Whether there's a offset during observing
OFFSET_V=                 0.00 / Offset value in arcsecond
GL      =           127.544691 / [deg] Galactic longitude of object
GB      =           -59.082059 / [deg] Galactic latitude of object
DESIG   = 'LAMOST J010055.84+034216.5' / Designation of LAMOST target
FIBERID =                   17 / Fiber ID of Object
CELL_ID = 'E1008   '           / Fiber Unit ID on the focal plane
X_VALUE =              350.193 / [mm] X coordinate of object on the focal plane
Y_VALUE =              673.418 / [mm] Y coordinate of object on the focal plane
OBJNAME = '2551493942881565056 ' / Name of object
OBJTYPE = 'Star    '           / Object type from input catalog
TSOURCE = 'LAMOST   '          / Name of input catalog
TCOMMENT= '        '           / Target information
TFROM   = '        '           / Target catalog
FIBERTYP= 'Obj     '           / Fiber type of object
FIBERMAS=                    0 / Bitmask of warning values, 0 means all is well
MAGTYPE = 'ugriz   '           / Magnitude type of object
MAG1    =                99.00 / [mag] Mag1 of object
MAG2    =                99.00 / [mag] Mag2 of object
MAG3    =                99.00 / [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
SKYLIST = 'skylines.dat'       / Sky emission line list
NEXP_B  =                    9 / Number of valid blue exposures
COMBIN_B=                    T / Whether the combined data of B band exists
NEXP_R  =                    9 / Number of valid red exposures
COMBIN_R=                    T / Whether the combined data of R band exists
SCAMEAN =                 4.72 / [ADU] Mean level of scatter light

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

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

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

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

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

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

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

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

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

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

OFFSET Keyword --- The value field shall contains a boolean value, T(ure) or F(alse), 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 contains a real floating-point number giving the offset value in unite of arcsec.

GL Keyword --- The The value field shall contains a real floating-point number, which gives the galactic longitude of target.

GB Keyword --- The The value field shall contains a real floating-point number, which gives the galactic latitude of target.

DESIG Keyword --- The value field shall contains 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 contains 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 contains 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 Their 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 contains character string, giving the name ID of object that determined by the RA, DEC and HTM method.

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

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

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

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

FIBERTYP Keyword --- The value field shall contains 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 a object, including star, galaxy and so on. Sky indicates 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 fiber is not used, goes to a wrong position, or does not work respectively.

FIBERMAS Keyword --- The value field shall contains 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. If the value of a bit is 1, it represents the fiber has associated problem. The following table lists the associated fiber problems when a bit of the binary number is 1.

Table 1: 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 solutionh
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 Near a whopping fiber Sky fiber shows extreme residuals

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

MAG1, MAG2, MAG3, MAG4, MAG5, MAG6 and MAG7 Keywords The value field shall contains 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 contains a character string giving the type of observation targets, which include object, flat, bias and arc lamp.

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

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

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

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

COMBIN_B and COMBIN_R Keywords --- The value field shall contains a boolean value (T or F), which indicates whether the coadded B or R band spectrum exists.

SCAMEAN Keyword --- The value field shall contains 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.

2.3.5 Spectrograph Parameters Keywords

SPID    =                    1 / Spectrograph ID
SPRA    =          236.8408024 / [deg] Average RA of this spectrograph
SPDEC   =           12.0844527 / [deg] Average DEC of this spectrograph
SLIT_MOD= 'x2/3    '           / Slit mode, x1, x2/3 or x1/2

SPID Keyword --- The value field shall contains 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 contains a character string giving the mode of slit, which includes x1, x2/3 and x1/2. At present, only mode x2/3 is available, which responds spectra resolution equals to 1800.

2.3.6 Weather Condition Keywords

TEMPCCDB=              -112.70 / [deg] The temperature of blue CCD
TEMPCCDR=              -195.90 / [deg] The temperature of red CCD
SEEING  =                 2.60 / [arcsec] Seeing during exposure
MOONPHA =                17.59 / [day] Moon phase for a 29.53 days period
TEMP_AIR= '        '           / [deg] Temperature outside dome
TEMP_FP =                 3.30 / [degree celsius] Temprature of the focalplane
DEWPOINT= '        '           / [deg]
DUST    = '        '           / Reservation
HUMIDITY= '        '           /
WINDD   = '        '           / [deg] Wind direction
WINDS   = '        '           / [m/s] Wind speed
SKYLEVEL= '        '           / Reservation

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

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

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

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

WINDD Keyword --- The value field shall contains 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 contains 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.

2.3.7 Data Reduction Parameters Keywords

EXTRACT = 'aperture'           / Extraction method
SFLATTEN=                    T / Super flat has been applied
PCASKYSB=                    T / PCA sky-subtraction has been applied
NSKIES  =                  105 / Sky fiber number
SKYCHI2 =                  2.3 / Mean chi^2 of sky-subtraction
SCHI2MIN=                  1.8 / Minimum chi^2 of sky-subtraction
SCHI2MAX=                  3.2 / Maximum chi^2 of sky-subtraction
NSTD    =                    4 / Number of (good) standard stars
FSTAR   = '148-064-236-094'    / FiberID of flux standard stars
FCBY    = 'auto    '           / Standard stars origin (auto, manual or catalog)
HELIO   =                    T / Heliocentric correction
HELIO_RV=            -22.47678 / [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 contains 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, and it can be estimated through spline fitting the flat flux of all fibers in a spectrograph.

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 angstrom.

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

SKYCHI2 Keyword --- The value field shall contains 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 contains 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 contains 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 contains a non-negative integer, which shows the number of flux standard stars with good spectra quality.

FSTAR Keyword --- The value field shall contains a character string giving the fiber identity numbers of flux standard stars, which are separated by the symbol ‘-’.

FCBY Keyword --- The value field shall contains 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 contains 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 contains a integer, which gives number of linear-log10 coefficients.

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

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

COEFF1 Keyword --- The value field shall contains 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 contains a real floating-point number, which gives the coordinate value of the reference pixel provided by the CRPIX1 keyword.

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

CRPIX1 Keyword --- The value of this keyword shall contains a integer, which sets the reference pixel location on pixel axis.

CTYPE1 Keyword --- The value field shall contains a character string, which will have the value ‘LINEAR’ to define the wavelength axes to be linear.

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.

2.4 Extention 1 and 2

If a LAMOST target has coadded B and R band spectra, the extension 1 and 2 provide the information of their coadded spectra, otherwise the two extension do not have the data array as the primary extension.

In this section, we only introduce extension 1 and 2 for targets which have the coadded spectra. Following sub-section 2.4.1 will introduce each keyword in the header file, and the data array will be presented in the sub-section 2.4.2.

2.4.1 Keywords in the Header File

In this sub-section, we will introduce each keyword in the header file of extension 1 and 2, and all keywords are shown as follows.

XTENSION= 'BINTABLE'           /Binary table written by MWRFITS v1.11b
BITPIX  =                    8 /Required value
NAXIS   =                    2 /Required value
NAXIS1  =                   16 /Number of bytes per row
NAXIS2  =                 3769 /Number of rows
PCOUNT  =                    0 /Normally 0 (no varying arrays)
GCOUNT  =                    1 /Required value
TFIELDS =                    5 /Number of columns in table
EXTNAME = 'COADD_B '           / The extension name
LMJMLIS0= '83556038-83556052-83556065' / Local Modified Julian Minute list
LMJMLIS1= '83556078-83556092-83556105' / Local Modified Julian Minute list
LMJMLIS2= '83556119-83556132-83556146' / Local Modified Julian Minute list
SNR     =                26.79 / Signal to noise ratio
LAMPLIST= 'lampsc_med.dat'     / Arc lamp emission line list
TTYPE1  = 'FLUX    '           /
TTYPE2  = 'IVAR    '           /
TTYPE3  = 'LOGLAM  '           /
TTYPE4  = 'ANDMASK '           /
TTYPE5  = 'ORMASK  '           /
TFORM1  = 'E       '           /
TFORM2  = 'E       '           /
TFORM3  = 'E       '           /
TFORM4  = 'I       '           /
TFORM5  = 'I       '           /

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. 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.

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.

LMJMLIS1-n Keyword --- This keyword contains a character string to be used to show local modified Julian Minutes (LMJM) of N exposures. For each LMJMLISi (i = 1,2,…n), it includes LMJM of three exposures at most. If the number of exposures (N) is larger than three, then n can be obtained with the equation of n = floor(N / 3) + 1, where floor represents round down.

SNR Keyword --- The value field for this keyword shall contains a real floating-point, which is the median of S/Ns of all pixels. The S/N of each pixel is calculated by the equation of flux*(inverse variance) ^ 0.5.

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

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

TFORMn 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 and 2 have five rows and NAXIS1 (a keyword explained previously) columns, and table 2 explains the data in each row.

Table 2: Data array of extension 1 and 2

Row Number Data Type
5 Ormask float
4 Andmask float
3 WaveLength float
2 Inverse Variance float
1 Flux float

The first row is flux, and the second row stores the ‘inverse variance’ of the uncertainties (one over sigma-squared), which can be used to estimate S/N of each pixel (flux*(inverse variance) ^ 0.5). The third row stores logarithmic wavelength. The ‘andmask’ information in fourth row is a decimal integer determined by a six-bit binary number shown in table 3, which represents six situations respectively listed in table 4. The associated bit of ‘andmask’ will be set to 1, if the case always appears in each exposure. Like the ‘andmask’, the ‘ormask’ information in fifth row 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 3: Six bits of ‘Andmask’ and ‘Ormask’

6 5 4 3 2 1

Table 4: 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

If you want to check which case in table 4 has happened in the spectrum reduction process, you can firstly convert the decimal ‘Andmask’ or ‘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’.

2.5 Extension 3 to (N-1)

In this section, we will introduce the single exposure extensions. In the title of this section, N is the total number of extensions which can be obtained from the keyword ‘N_EXTEN’ in the header of primary extension. Assuming the target has n B band and n R band single exposure spectra, N is equal to 2n + 3.

In the following sub-section, we will introduce each keyword in the header file, and the structure of data array.

2.5.1 Keywords in the Header File

In this sub-section, all keywords in the header are shown as follows, and they are explained in detail.

XTENSION= 'BINTABLE'           /Binary table written by MWRFITS v1.11b
BITPIX  =                    8 /Required value
NAXIS   =                    2 /Required value
NAXIS1  =                   14 /Number of bytes per row
NAXIS2  =                 4136 /Number of rows
PCOUNT  =                    0 /Normally 0 (no varying arrays)
GCOUNT  =                    1 /Required value
TFIELDS =                    4 /Number of columns in table
EXTNAME = 'B-83556105'         / The extension name
LMJM    = '83556105'           / Local Modified Julian Minute
EXPTIME =                  600 / [s] Exposure duration time
SNR     =                 7.93 / Signal to noise ratio
LAMPLIST= 'lampsc_med.dat'     / Arc lamp emission line list
TTYPE1  = 'FLUX    '           /
TTYPE2  = 'IVAR    '           /
TTYPE3  = 'LOGLAM  '           /
TTYPE4  = 'PIXMASK '           /
TFORM1  = 'E       '           /
TFORM2  = 'E       '           /
TFORM3  = 'E       '           /
TFORM4  = 'I       '           /

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. 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.

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.

LMJM Keyword --- This keyword contains a character string to show the local modified Julian Minute at the start of exposure.

EXPTIME Keyword --- The value field for this keyword shall contains a real floating-point, which gives the exposure duration time.

SNR Keyword --- The value field for this keyword shall contains a real floating-point, which is the median of S/Ns of all pixels. The S/N of each pixel is calculated by the equation of flux*(inverse variance) ^ 0.5.

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

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

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

2.5.2 Data Array

In this sub-section, we describe the structure of data array of a single exposure extension, and it is shown in table 5. Like the data array of extension 1 and 2, they are flux, inverse variance, and logarithmic wavelength from the first to third row. The different is that the data array of single exposure only has four rows, and the fourth row is the ‘Pixmask’, which is a decimal integer determined by a six-bit binary number. As the ‘Andmask’ and ‘Ormask’, each bit of the ‘Pixmask’ represents each issues of each pixel listed in table 4, and it will be 1 if the problem happens.

Table 5: Data array

Row Number Data Type
4 Pixmask float
3 WaveLength float
2 Inverse Variance float
1 Flux float

Section 3. LAMOST Catalogs

In this section, we will introduce four LAMOST medium resolution spectral (MRS) catalogs, which are also published in this data release and can be available from the website of http://dr6.lamost.org/catalogue. They are the LAMOST MRS General Catalog, the LAMOST MRS Parameter Catalog, the LAMOST MRS Observed Plate Information Catalog, and the LAMOST MRS Input Catalog, respectively. The LAMOST MRS General Catalog publish 35 basic parameters and four radial velocity measurements for all single exposure and coadded spectra, and the LAMOST MRS Parameter Catalog publish other 14 parameters not included in above table for a fraction of above spectra. In addition, the LAMOST MRS Observed Plate Information Catalog provides nine basic parameters of each observed plate of the MRS survey, and the LAMOST MRS Input Catalog provide 27 parameters for each target of the observation plan.

The following table 6, 7, 8, and 9 separately show all fields of the above four catalogs, and provide clear comment for each field. Most fields in these tables are explained in detail in sub-section 2.3, and we only introduce the fields, which are not introduced in previous section.

3.1 LAMOST MRS General Catalog

In this sub-section, we will present the LAMOST MRS General Catalog, and 35 basic parameters of 4,509,135 single exposure spectra and 1,279,640 coadded spectra are published in this table.

All fields of this catalog are listed in the table 6, and most majorities of them are explained in section 2.3 in detail. We only introduce fields not mentioned above.

First, we artificially add offsets to the equatorial coordinates from input catalog to prevent saturation for a fraction of luminous stars during observation. Thus, we add four new fields in this catalog and the LAMOST MRS Parameter Catalog, and they are ‘ra_obs’, ‘dec_obs’, ‘offsets’ and ‘offset_v’ respectively. The ‘ra_obs’ and ‘dec_obs’ are fiber pointing right ascension and declination during observation, and the ‘ra’ and ‘dec’ are the equatorial coordinates from the input catalog. The ‘offsets’ represents whether there is a fiber offset during observation, and the ‘offset_v’ gives the offset value of equatorial coordinator in the input catalog if the ‘offsets’ field is true.

Then, the catalog provide four measurements of radial velocity and their errors, and they are ‘rv_71el0’, ‘rv_71el1’, ‘rv_ku0’, ‘rv_ku1’, ‘rv_71el0_err’, ‘rv_71el1_err’, ‘rv_ku0_err’, and ‘rv_ku1_err’ respectively. The ‘rv_71el0’ and ‘rv_ku0’ were both determined by the cross correlation method, the difference lies in the adopted templates. The ‘rv_71el0’ used 71 manually selected ELODIE templates, but ‘rv_ku0’ adopted 483 selected KURUCZ synthetic templates. To estimate the uncertainties of ‘rv_71el0’ and ‘rv_ku0’, chi-squares between LAMOST spectra and best-fitted templates were firstly determined, then ‘rv_71el0_err’ and ‘rv_ku0_err’ were both calculated by the relationship of chi-square and S/N. In addition, the ‘rv_71el1’ and ‘rv_ku1’ are calibrated velocities of ‘rv_71el0’ and ‘rv_ku0’, and they were calibrated by the radial velocity standard stars of APOGEE provided in Huang, Y. et al (2018) $^{[1]}$. It should be noted that ‘rv_71el1’ and ‘rv_ku1’ have only corrected the systematic errors between spectrographs, which do not include systematic errors between fibers and exposures, and the detailed correction method was introduced in Wang, R. et al (2019; In preparation). The ‘rv_71el1_err’ and ‘rv_ku1_err’ are errors of ‘rv_71el1’ and ‘rv_ku1’, which were determined by the error propagation method.

Last, other three fields are also provided in this catalog. ‘lmjm’ is the modified Julian minutes at the beginning of each exposure, and it is null for the coadd spectrum. The ‘band’ field has two values of B and R, which represent B and R band spectra, respectively. ‘coadd’ has two values of 0 and 1, which shows whether the spectrum is a coadd one. On the website http://dr6.lamost.org/catalogue, we provide two formats of the LAMOST MRS General Catalog, which include a FITS table and a CSV table, and the two files have the same contents.

On the website http://dr6.lamost.org/catalogue, we provide two formats of the LAMOST MRS General Catalog, which include a FITS table and a CSV table, and the two files have the same contents.

Table 6: LAMOST MRS General Catalog

Field (unit) Type Comment
obsid long integer Unique Spectra ID
designation varchar 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
lmjm varchar Local Modified Julian Minute
band char Having two values of B and R, which represent B and R band spectra
ra_obs (degree) float Fiber Pointing Right Ascension
dec_obs (degree) float Fiber Pointing Declination
snr float The median value of all pixel S/Ns in B band spectrum or R band
objtype varchar Object Type
magtype varchar 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 varchar Organization or person who submit input catalog
fibertype varchar Fiber Type of target [Obj, Sky, F-std, Unused, PosErr, Dead]
tfrom varchar Input catalog submitted by an organization or a person determined by the objsourc
tcomment varchar Target ID from SDSS, UCAC4, PANSTAR and other catalogue
offsets bool Whether there is a fiber offset during observation
offset_v (arcsec) float If offset is true, it 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
rv_71el0(km/s) float Radial Velocity measured with 71 selected ELODIE templates
rv_71el0_err(km/s) float Uncertainty of rv_71el0
rv_71el1(km/s) float Calibrated rv_71el0
rv_71el1_err(km/s) float Uncertainty of rv_71el0
rv_ku0(km/s) float Radial Velocity measured with 483 selected KURUCZ templates
rv_ku0_err(km/s) float Uncertainty of rv_ku0
rv_ku1(km/s) float Calibrated rv_ku0
rv_ku1_err(km/s) float Uncertainty of rv_ku1
coadd bool A flag to show whether it is a coadd spectrum

3.2 LAMOST MRS Parameter Catalog

In this sub-section, we introduce the LAMOST MRS Parameter catalog. We totally published parameters for 921,145 single exposure spectra and 359,991 coadded spectra of B band in this catalog, and the B band S/Ns of these spectra are larger than and equal to 10.

Table 7 lists all fields of this catalog, and fields before the ‘teff’ have been introduced in subsection 3.1. The ‘teff’, ‘logg’, ‘feh’, ‘teff_err’, ‘logg_err’, and ‘feh_err’ fields respectively provide the effective temperature, surface gravity, metallicitie and their errors, which were determined by the LAMOST Stellar Parameter pipeline. The fields of ‘vsini_el’ and ‘vsini_el_err’ are projected rotation velocity and its uncertainty, and ‘vsini_el’ was measured by the template match method, which used the ELODIE templates. The ‘afe’ and ‘afe_err’ fields are alpha element abundance and its uncertainty. For giants, the Convolutional neural network (CNN) method was used to estimate alpha element abundance, which used the spectra both observed by the APOGEE and LAMOST as the training samples. For dwarfs, the template match method was adopted, which used the KURUCZ synthetic spectra as the templates. In this data release, we do not publish errors of rotation velocity and alpha element abundance, thus the values of vsini_el_err’ and ‘afe_err’ are null. In addition to radial velocities and errors mentioned in the above catalog, there are two other radial velocities and their errors provided in this catalog, and they are ‘rv_el0’, ‘rv_el1’, ‘rv_el0_err’, and ‘rv_el1_err’ respectively. ‘rv_el0’ and ‘rv_el0_err’ were calculated by the ULYSS software, and ‘rv_el1’ is the calibrated velocity of ‘rv_el0’. ‘rv_el0’ was calibrated using the method mentioned in 3.1, and its error was also estimated by the error propagation method.

We provide two formats of the LAMOST MRS Parameter catalogs, i.e., a FITS table and a CSV table, which can be available from the website http://dr6.lamost.org/catalogue.

Table 7: LAMOST MRS Parameter Catalog

Field (unit) Type Comment
obsid long integer Unique Spectra ID
designation varchar 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
lmjm varchar Local Modified Julian Minute
band char Having two values of B and R, which represent B and R band spectra
ra_obs (degree) float Fiber Pointing Right Ascension
dec_obs (degree) float Fiber Pointing Declination
snr float The median value of all pixel S/Ns in B band spectrum or R band
objtype varchar Object Type
magtype varchar 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 varchar Organization or person who submit input catalog
fibertype varchar Fiber Type of target [Obj, Sky, F-std, Unused, PosErr, Dead]
tfrom varchar Input catalog submitted by an organization or a person determined by the objsourc
tcomment varchar Target ID from SDSS, UCAC4, PANSTAR and other catalogue
offsets bool Whether there is a fiber offset during observation
offset_v (arcsec) float If offset is true, it 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 which are obtained by the software of ULYSS
teff_err (K) float Effective Temperature Uncertainty
logg float Surface Gravity which are obtained by the software of ULYSS
logg_err float Surface Gravity Uncertainty
feh float Metallicity which are obtained by the software of ULYSS
feh_err float Metallicity Uncertainty
vsini_el float Projected Rotation Velocity
vsini_el_err float Uncertainty of vsini_el
rv_el0 (km/s) float Radial Velocity measured with the ELODIE templates
rv_el0_err (km/s) float Uncertainty of rv_el0
rv_el1 (km/s) float Calibrated rv_el0
rv_el1_err (km/s) float Uncertainty of rv_el1
rv_71el0(km/s) float Radial Velocity measured with 71 selected ELODIE templates
rv_71el0_err(km/s) float Uncertainty of rv_71el0
rv_71el1(km/s) float Calibrated rv_71el0
rv_71el1_err(km/s) float Uncertainty of rv_71el0
rv_ku0 (km/s) float Radial Velocity measured with 483 selected KURUCZ templates
rv_ku0_err (km/s) float Uncertainty of rv_ku0
rv_ku1 (km/s) float Calibrated rv_ku0
rv_ku1_err (km/s) float Uncertainty of rv_ku1
afe float [α/Fe]
afe_err float Uncertainty of [α/Fe]
coadd bool A flag to show whether it is a coadd spectrum

3.3 LAMOST MRS Observed Plate Information Catalog

In this sub-section, we will introduce the LAMOST MRS observed plate information catalog, which have the same table structure as the ‘Observed Plate Information Catalog’ table of low-resolution data release. Except the ‘obsdate’ and ‘planid’ fields also in other two catalogs, we also provide other seven basic information of 325 published plates in this catalog as described in table 8. The fields of ‘ra’ and ‘dec’ are the right ascension and declination of center star of each plate, and the field ‘mag’ is the magnitude of center star. The field ‘seeing’ is the dome seeing of the first exposure, and the field ‘exptime’ is the total exposure time of n time exposures. The field ‘lmjm’ is a string which provides the local modified Julian minute list for each plate, and it is separated by commas. For example, the ‘lmjmlist’ for a plate is ‘84108765,84108789,84108813’, which represents the plate has three exposures, and the it provides the local modified Julian minute at the beginning time of each exposure for this plate. Last, the ‘pid’ is the unique ID of each plate.

We provide a CSV table to download, which can be available from the website http://dr6.lamost.org/catalogue.

Table 8: LAMOST MRS 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
lmjmlist Integer A string which provide the Local Modified Julian Minute list

3.4 LAMOST MRS Input Catalog

In this sub-section, we will introduce the LAMOST MRS input catalog. This catalog includes 27 fields for 1,299,500 targets. There are three fields which are not included in above three tables, they are the ‘unitid’, ‘epoch’ and ‘tname’ fields respectively. The ‘unitid’ field is the ID of 4000 fiber units, and the ‘tname’ field provides unique ID of this catalog for each target. Besides, values of the ‘epoch’ field are all ‘J2000’.

We provide a .txt table to download, which can be available from the website http://dr6.lamost.org/catalogue.

Table 9: LAMOST MRS Input catalog

Field (unit) Type Comment
obsID long integer Unique Spectra ID
obsDate float Target Observation Date
planID char Plan Name
spID integer Spectrograph ID
fiberID integer Fiber ID
unitid char ID of 4000 fiber unites
ra_obs(degree) float Fiber Pointing Right Ascension
dec_obs(degree) float Fiber Pointing Declination
objtype varchar Object Type
magtype varchar 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 varchar Organization or person who submit input catalog
fibertype varchar Fiber Type of target [Obj, Sky, F-std, Unused, PosErr, Dead]
tfrom varchar Input catalog submitted by an organization or a person determined by the objsourc
tcomment varchar Target ID from SDSS, UCAC4, PANSTAR and other catalogue
offset bool Whether there is a fiber offset during observation
offset_v (arcsec) float If offset is true, it gives the offset distance
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

Bibliography

  1. Huang, Y., Liu, X.W., Chen, B.Q., et al. 2018, A New Catalog of Radial Velocity Standard Stars from the APOGEE Data, AJ, 156, 90.