svenbuder / galah_dr2

In this repository, we describe the most basic routines to use GALAH Data Release 2.

GALAH_DR2

In this repository, we describe the most basic routines to use GALAH Data Release 2. The GALAH collaboration released its second Data Release April 2018.

You can download the FITS file of GALAH DR2 from:

https://datacentral.org.au/teamdata/GALAH/public/

An example X-match with Gaia DR1 could be:

SELECT *
FROM gaiadr1.gaia_source AS gaia
INNER JOIN gaiadr1.tmass_best_neighbour AS tmass_xmatch
	ON gaia.source_id = tmass_xmatch.source_id
INNER JOIN gaiadr1.tmass_original_valid AS tmass
	ON tmass.tmass_oid = tmass_xmatch.tmass_oid
INNER JOIN user_sbuder.galah_dr2 AS galah_dr2
	ON tmass.designation = galah_dr2.star_id

If you have downloaded the file e.g. as 'GALAH_DR2.fits', do the following:

from astropy import table
t = table.Table()
galah_dr2 = t.read('GALAH_DR2.fits')

The FITS files contains the keywords in the table below

Field	Units	Data type	Description
star_id		char[16]	2MASS ID number by default, UCAC4 ID number if 2MASS unavailable (begins with UCAC4-)
star_id		char[16]	2MASS ID number by default, UCAC4 ID number if 2MASS unavailable (begins with UCAC4-)
sobject_id		int64	Unique per-observation star ID
gaia_id		int64	\Gaia\ DR1 identifier
ndfclass		char[8]	Observation type (MFOBJECT (regular observation) or MFFLX (benchmark observation))
field_id		int64	GALAH field identification number
raj2000	deg	float64	Right ascension from 2MASS, J2000
dej2000	deg	float64	Declination from 2MASS, J2000
jmag	mag	float64	J magnitude from 2MASS
hmag	mag	float64	H magnitude from 2MASS
kmag	mag	float64	K magnitude from 2MASS
vmag_jk	mag	float64	Synthetic V magnitude calculated from JHK, used for target selection
e_jmag	mag	float64	Uncertainty in J magnitude, from 2MASS
e_hmag	mag	float64	Uncertainty in H magnitude, from 2MASS
e_kmag	mag	float64	Uncertainty in K magnitude, from 2MASS
snr_c1		float64	Signal to noise per pixel in the HERMES blue channel
snr_c2		float64	Signal to noise per pixel in the HERMES green channel
snr_c3		float64	Signal to noise per pixel in the HERMES red channel
snr_c4		float64	Signal to noise per pixel in the HERMES IR channel
rv_synt	km/s	float64	Radial velocity from cross-correlation against synthetic spectra
rv_obst	km/s	float64	Radial velocity from internal cross-correlation against data
rv_nogr_obst	km/s	float64	Radial velocity from internal cross-correlation against data, uncorrected for gravitational redshift
e_rv_synt	km/s	float64	Uncertainty in rv_synt
e_rv_obst	km/s	float64	Uncertainty in rv_obst
e_rv_nogr_obst	km/s	float64	Uncertainty in rv_nogr_obst
chi2_cannon		float64	Summed chi-squared over all spectral pixels
sp_label_distance		float64	Label distance similar to \citet{Ho2017
flag_cannon		int64	Flags for spectrum information in a bitmask format
			0=No flag
			+1 The Cannon starts to extrapolate. For some stars the values could be incorrect.
			+2 The chi2 of the best fitting model spectrum is significantly higher or lower
			+4 Reduction flag raised
			+8 Binary star
			+16 Negative flux
			+32 Oscillating continuum
			+64 General reduction issues
			+128 Emission lines
teff	K	float64	Effective temperature
e_teff	K	float64	Uncertainty of teff
logg	dex	float64	Surface gravity
e_logg	dex	float64	Uncertainty of logg
fe_h	dex	float64	Iron abundance (not overall metallicity [M/H])
e_fe_h	dex	float64	Uncertainty in fe_h
vmic	km/s	float64	Microturbulent velocity
e_vmic	km/s	float64	Uncertainty in vmic
vsini	km/s	float64	Line of sight rotational velocity
e_vsini	km/s	float64	Uncertainty in vsini
alpha_fe	dex	float64	alpha-enhancement, determined as an error-weighted combination of Mg, Si, Ca, Ti abundances
e_alpha_fe	dex	float64	Uncertainty in alpha_fe
x_fe	dex	float64	[X/Fe] abundance for element X.
e_x_fe	dex	float64	Uncertainty in x_fe
flag_x_fe		int64	Flags indicating difficulty in abundance determination in a bitmask format
			0=No flag
			+1 Line strength below 2-sigma upper limit
			+2 The Cannon starts to extrapolate. For some stars the values could be incorrect.
			+4 The chi2 of the best fitting model spectrum is significantly higher or lower.
			+8 flag_cannon is not 0

galah_dr2's Issues

Broken Link

The link in the README should be updated to the current public directory: https://datacentral.org.au/teamdata/GALAH/public/