Description of the second release of LSS-GAC value-added catalogues.
For a description of the format of catalogues, please see Table 5 of Xiang et al. 2017, MNRAS, in press.
https://arxiv.org/pdf/1701.05409v1.pdf
Col. & Name & Description
1 & spec_id & LAMOST unique spectral ID, in format of date-plateid-spectrographid-fibreid
2 & date & Date of observation
3 & plate & LAMOST plate ID, not necessarily unique
4 & sp_id & LAMOST spectrograph ID, ranging from 1 to 16
5 & fiber_id & LAMOST fibre ID for a given spectrograph, ranging from 1 to 250
6 & objid & Object ID in the input catalogues
7 & objtype & Initial object type from the survey input catalogues
8 & ra & Right ascension of J2000.0 (o)
9 & dec & Declination of J2000.0 (o)
10 & l & Galactic longitude (o)
11 & b & Galactic latitude (o)
12 & jd & Julian days at the middle time of the first exposure
13 & moonphase & Moon phase at the middle time of the first exposure
14 & monodis & Moon distance at the middle time of the first exposure
15 & airmass & Airmass at the middle time of the first exposure
16 & alt & Altitude (in degrees) of the telescope at the middle time of the first exposure
17 & az & Azimuth angle (in degrees) of the telescope at the middle time of the first exposure
18 & ha & Hour angle (in degrees) of the telescope at the middle time of the first exposure
19 & badfiber & Is it a bad fibre? (yes - 1, no - 0)
20 & satflag & Is the spectrum saturated? (yes - 1, no - 0)
21 & brightflag & Are there bright stars (snr_b > 300) in the nearby 5 fibres (yes - 1, no - 0)
22 & brightsnr & Largest snr_b in the nearby 5 fibres
23 & object_sky_ratio & Object to sky flux ratio
24 & snr_b & S/N(4650A) per pixel
25 & snr_r & S/N(7450A) per pixel
26 & uqflag & Uniqueness flag. If the target has been observed n times, then uqflag runs from 1 to n, with 1 denoting
& & the spectrum of the highest snr_b
27 & vr & Radial velocity yielded by LSP3, after corrected for a systematic offset of -3.1 km/s
28 & err_vr & Error of radial velocity yielded by LSP3 (km/s)
29 & teff & Recommended Teff (K)
30 & err_teff & Error of the recommended Teff
31 & teff_from & Which method is the recommended Teff adopted
32 & logg & Recommended log g (cm/s^2)
33 & err_logg & Error of the recommended log g
34 & logg_from & Which method is the recommended log g adopted
35 & mv & Recommended absolute magnitude in V -band
36 & err_mv & Error of MV
37 & mv_from & Which method is the recommended MV adopted
38 & mk & Recommended absolute magnitude in Ks-band
39 & err_mk & Error of MKs
40 & mk_from & Which method is the recommended MKs adopted
41 & feh & Recommended [Fe/H] (dex)
42 & err_feh & Error of the recommended [Fe/H]
43 & feh_from & Which method is the recommended [Fe/H] adopted
44 & afe & Recommended [Fe] (dex)
45 & err_afe & Error of the recommended [Fe]
46 & afe_from & Which method is the recommended [Fe] adopted
47 & am & element to metal abundance ratio [M] estimated by training the LAMOST-APOGEE stars (dex)
48 & err_am & Error of [M]
49 & mh & Metal abundance [M/H] estimated by training the LAMOST-APOGEE stars (dex)
50 & err_mh & Error of [M/H]
51 & ch & Carbon abundance [C/H] estimated by training the LAMOST-APOGEE stars (dex)
52 & err_mh & Error of [C/H]
53 & nh & Nitrogen abundance [N/H] estimated by training the LAMOST-APOGEE stars (dex)
54 & err_nh & Error of [N/H]
55 & ebv & Recommended E(B - V)
56 & dist & Recommended distance (pc)
57 & err_dist & Error of the recommended distance
58 & dist_from & Which method is the recommended distance adopted
59 & vr_peak_corr_coeff & Peak correlation coefficient for radial velocity estimation
60 & vr_flag & Flag to describe value of 'vr_peak_corr_coeff', n means the vr_peak_corr_coeff
& & is smaller than the median value of the sample stars with the same snr_b by n×MAD
61 & teff1 & Teff estimated with the weighted-mean algorithm (K)
62 & err_teff1 & Error of teff1
63 & teff2 & Teff estimated with the KPCA method (K)
64 & err_teff2 & Error of teff2
65 & logg1 & Log g estimated with the weighted-mean algorithm (cm/s^2)
66 & err_logg1 & Error of logg1
67 & logg2 & Log g estimated with the KPCA method using MILES stars as training set (cm/s^2)
68 & err_logg2 & Error of logg2
69 & logg3 & Log g estimated with the KPCA method using LAMOST-Kepler stars as training set (cm/s^2)
70 & err_logg3 & Error of logg3
71 & mv1 & MV estimated with the KPCA method taking LAMOST-Hipparcos stars as training set using 300 PCs (mag)
72 & err_mv1 & Error of mv1
73 & mv2 & MV estimated with the KPCA method taking LAMOST-Hipparcos stars as training set using 100 PCs (mag)
74 & err_mv2 & Error of mv2
75 & mk1 & MKs estimated with the KPCA method taking LAMOST-Hipparcos stars as training set using 300 PCs (mag)
76 & err_mk1 & Error of mk1
77 & mk2 & MKs estimated with the KPCA method taking LAMOST-Hipparcos stars as training set using 100 PCs (mag)
78 & err_mk2 & Error of mk2
79 & feh1 & [Fe/H] estimated with the LSP3 weighted mean algorithm (dex)
80 & err_feh1 & Error of feh1
81 & feh2 & [Fe/H] estimated with the LSP3 KPCA method by training the MILES stars (dex)
82 & err_feh2 & Error of feh2
83 & feh3 & [Fe/H] estimated with the LSP3 KPCA method by training the LAMOST-APOGEE stars (dex)
84 & err_feh3 & Error of feh3
85 & afe1 & [Fe] estimated by template matching with synthetic spectra using spectral segments
& & of 3900 - 3980A, 4400 - 4600A and 5000 - 5300A (dex)
86 & err_afe1 & Error of afe1
87 & afe2 & [Fe] estimated by template matching with synthetic spectra using spectral segments
& & of 4400 - 4600A and 5000 - 5300A (dex)
88 & err_afe2 & Error of afe2
89 & afe3 & [Fe] estimated with the LSP3 KPCA method using the LAMOST-APOGEE training set (dex)
90 & err_afe3 & Error of afe3
91 & besttemp_chi2 & Name of the best-matching template star with 2 algorithm
92 & besttemp_corr & Name of the best-matching template star with correlation algorithm
93 & typeflag_chi2 & Stellar types of the best-matching template star with 2 algorithm
94 & typeflag_corr & Stellar types of the best-matching template star with correlation algorithm
95 & min_chi2 & Minimum^2 yielded by LSP3 from template matching with the MILES library
96 & chi2_flag & The 'min_chi2' is smaller than the median value of the sample stars in the same SNR and
& & atmospheric parameter bin by n×MAD
97 & dg_miles_tm & Maximum value of the kernel function for estimation of Teff and [Fe/H] with KPCA method
& & via training the MILES stars
98 & dg_miles_g & Maximum value of the kernel function for estimation of log g with KPCA method via training
& & the MILES stars
99 & dg_lm_kep & Maximum value of the kernel function for estimation of log g with KPCA method via training
& & the LAMOST-Kepler stars
100 & dg_lm_hip & Maximum value of the kernel function for estimation of absolute magnitudes with KPCA method
& & via training the LAMOST-Hipparcos stars
101 & dg_lm_apo & Maximum value of the kernel function for estimation of abundances with KPCA method via training
& & the LAMOST-APOGEE stars
102 & fuv & GALEX FUV band magnitude (mag)
103 & err_fuv & Error of fuv
104 & nuv & GALEX NUV band magnitude (mag)
105 & err_nuv & Error of nuv
106 & g & XSTPS-GAC g-band magnitude (mag)
107 & err_g & Error of g
108 & r & XSTPS-GAC r-band magnitude (mag)
109 & err_r & Error of r
110 & i & XSTPS-GAC i-band magnitude (mag)
111 & err_i & Error of i
112 & J & 2MASS J-band magnitude (mag)
113 & err_J & Error of J
114 & H & 2MASS H-band magnitude (mag)
115 & err_H & Error of H
116 & Ks & 2MASS Ks-band magnitude (mag)
117 & err_Ks & Error of Ks
118 & w1 & WISE W1-band magnitude (mag)
119 & err_w1 & Error of w1
120 & w2 WISE & W2-band magnitude (mag)
121 & err_w2 & Error of w2
122 & w3 WISE & W3-band magnitude (mag)
123 & err_w3 & Error of w3
124 & w4 WISE & W4-band magnitude (mag)
125 & err_w4 & Error of w4
126 & ph_qual_2mass & 2MASS photometric quality flag
127 & ph_qual_wise & WISE photometric quality flag
128 & var_flag_wise & WISE variability flag
129 & ext_flag_wise & WISE extended source flag
130 & cc_flag_wise & WISE contamination and confusion flag
131 & ebv_sfd & E(B - V ) from the SFD extinction map (mag)
132 & ebv_sp & E(B - V ) derived from the star pair method (mag)
133 & err_ebv_sp & Error of ebv_sp
134 & ebv_mod & E(B - V ) derived by comparing the observed and synthetic model atmosphere colours (mag)
135 & ebv_phot & E(B - V ) derived by fitting multiband photometry to the empirical stellar loci (Chen et al. 2014) (mag)
136 & dist_em1 & Distance derived using the empirical relations of absolute magnitudes as a function of stellar atmospheric
& & parameters as yielded by the MILES stars using the recommended atmospheric parameters
137 & err_dist_em1 & Error of dist_em1
138 & dist_em2 & Distance derived using the empirical relations of absolute magnitudes as a function of stellar atmospheric
& & parameters as yielded by the MILES stars using the weighted-mean atmospheric parameters
139 & err_dist_em2 & Error of dist_em2
140 & dist_sp1 & Distance inferred from absolute magnitudes estimated with KPCA method using 300 PCs (pc)
141 & err_dist_sp1 & Error of dist_sp1
142 & dist_sp2 & Distance inferred from absolute magnitudes estimated with KPCA method using 100 PCs (pc)
143 & err_dist_sp2 & Error of dist_sp2
144 & dist_phot & Distance derived from the photometric parallax method (Chen et al. 2014) (pc)
145 & err_dist_phot & Error of dist_phot
146 & pmra_ppmxl & Proper motion in RA from the PPMXL catalogues (mas /yr)
147 & epmra_ppmxl & Error of pmra_ppmxl
148 & pmdec_ppmxl & Proper motion in Dec. from the PPMXL catalogues (mas /yr)
149 & epmdec_ppmxl & Error of pmdec_ppmxl
150 & pmra_ucac4 & Proper motion in RA from the UCAC4 catalogues (mas /yr)
151 & epmra_ucac4 & Error of pmra_ucac4
152 & pmdec_ucac4 & Proper motion in Dec. from the UCAC4 catalogues (mas /yr)
153 & epmdec_ucac4 & Error of pmdec_ucac4
154 & pmra_xuyi2mass & Proper motion in RA derived by comparing the XSTPS-GAC and 2MASS positions (mas /yr)
155 & pmdec_xuyi2mass & Proper motion in Dec. derived by comparing the XSTPS-GAC and 2MASS positions (mas /yr)
156 & x & x coordinate in a Galactocentric Cartesian reference system, positive towards the Galactic Centre (kpc)
157 & err_x & Error of x
158 & y & y coordinate in a Galactocentric Cartesian reference system, positive in the direction of disk rotation (kpc)
159 & err_y & Error of y
160 & z & z coordinate in a Galactocentric Cartesian reference system, positive towards the North Galactic Pole (kpc)
161 & err_z & Error of z
162 & u[2] & Galactic space velocities in the x direction computed from dist and the corrected PPMXL and UCAC4
& & proper motions, respectively, positive towards the Galactic Centre (km/s)
163 & err_u[2] & Error of u[2]
164 & v[2] & Galactic space velocities in the y direction computed from dist and the corrected PPMXL and UCAC4
& & proper motions, respectively, positive in the direction of Galactic rotation (km/s)
165 & err_v[2] & Error of v[2]
166 & w[2] & Galactic space velocities in the z direction computed from dist and the corrected PPMXL and UCAC4
& & proper motions, respectively, positive towards the North Galactic Pole (km/s)
167 & err_w[2] & Error of w[2]
168 & v_r[2] & Galactic space velocities in the r direction in a Galactocentric cylindrical polar coordinate system,
& & computed from dist and the corrected PPMXL and UCAC4 proper motions, respectively (km/s)
169 & err_v_r[2] & Error of v_r[2]
170 & v_phi[2] & Galactic space velocities in the direction in a Galactocentric cylindrical polar coordinate system,
& & computed from dist and the corrected PPMXL and UCAC4 proper motions, respectively,
& & positive in the direction of counter disk rotation (km/s)
171 &err_v_phi[2] & Error of v_phi[2]
172 &v_z[2] & Galactic space velocities in the z direction in a Galactocentric cylindrical polar coordinate system,
& & computed from dist and the corrected PPMXL and UCAC4 proper motions, respectively,
& & positive towards the North Galactic Pole (km/s)
173 & err_v_z[2] & Error of v_z[2]
174 & e[2] & Orbital eccentricities computed from dist_em and the corrected PPMXL and UCAC4 proper motions, respectively
175 & Rapo[2] & Maximum Galactic radii reached by the orbits computed with PPMXL and UCAC4 proper motions, respectively (kpc)
176 & Rperi[2] & Minimum Galactic radii reached by the orbits computed with PPMXL and UCAC4 proper motions, respectively (kpc)
177 & zmin[2] & Minimum height reached by the orbits computed with PPMXL and UCAC4 proper motions, respectively (kpc)
178 & zmax[2] & Maximum height reached by the orbits computed with PPMXL and UCAC4 proper motions, respectively (kpc)
Additional notes:
1) While most of the modifications and improvements in the data reduction and stellar parameter determination for LSS-GAC DR2 with respect to
DR1 have been described in the data release paper Xiang et al. (2017), there is however one significant modification left unspecified inadvertently.
For DR2, the spectral wavelength range 3930 - 5500 A was adopted for radial velocity measurements and atmospheric parameter determinations, DR1 used
4320 - 5500 A. Such an adjustment only affects slightly determinations of atmospheric parameters for the majority of stars but improves significantly
radial velocity measurements, especially for hot stars (Teff > 7000 K). Differences in radial velocity from DR1 and DR2 are negligible for cool stars
(Teff < 5000 K), but significant for hotter ones, on the level of 1 - 2 km/s for stars of 5000 < Teff < 7500 K and reaching 6 - 7 km/s for stars of
Teff > 8000 K.
2) Spectral ID (spec_id) in LSS-GAC DR2 is defined slightly differently than in DR1. Although spec_id is defined in the format of
date-plate-sptrographid-fiberid for both DR1 and DR2, in DR2 'sptrographid' is formated uniformly by two digits, and 'fiberid' by three digits.
For example, spec_id '20111027-B6212-7-68' in DR1 now becomes '20111027-B6212-07-068' in DR2.
3) 'spec_id" represents a unique spectrum but not necessarily a unique star. To find unique stars, one has to use 'uqflag' (uqflag = 1 will generates
unique stars), or to exclude duplicate observations by him/herself using the target coordinates. The latter is recommended, especially when one wants
to pick up results of all duplicate observations for a given, unique star.
4) About one per cent of the stars in the VB catalogue have no counterparts in the 2MASS/WISE catalog at the given positions. Most of them are likely
fake ones caused by contamination of nearby bright stars. The spectra and derived stellar parameters thus represent likely those of the nearby bright
stars. Users are advised to be cautious when using those spectra and parameters. A simple method to pick out those stars is to check the 2MASS/WISE
catalog, as those stars have no 2MASS/WISE magnitudes available. We thank Prof. Michael Ireland for reminding us this problem.