On this page we provide advice and instructions for using the GALAH DR4 catalogues. We would recommend taking the time to read Buder et al. (2024), which supplies even more information and quality assessment for GALAH DR4.

We highly recommend using the galah_dr4_allstar_240705.fits catalogue if you want to work with the GALAH DR4 stellar parameters and elemental abundances.

For more information, see our Catalogue documentation.

If your science case contains stellar parameters and elemental abundances, then we recommend the galah_dr4_allstar_240705.fits catalogue. It contains one entry per star.

There is an extended version called galah_dr4_allspec_240705.fits that contains one entry per observation. This table is for expert use only.

Consult the catalogue documentation for details on the catalogues and acquiring them. If you just want the entire galah_dr4_allstar_240705 catalogue, it can be directly directly downloaded, or with wget (removing the --spider flag):

wget --spider https://cloud.datacentral.org.au/teamdata/GALAH/public/GALAH_DR4/catalogs/galah_dr4_allstar_240705.fits

Overall, we make three recommendations: (1) snr_px_ccd3 > 30; (2) only stellar parameters for stars with flag_sp == 0; (3) only elemental abundances with flag_X_fe == 0.

For more information, see our Flag bitmask documentation.

The main recommended galah_dr4_allstar_240705 catalogue contains a number of flags. For most science cases, the most important to consider is the spectroscopic quality flag (flag_sp). flag_sp folds in many potential sources of errors in the input values (e.g., missing data, very low signal spectra, poor analysis results, possible binarity). By default, we recommend that users only consider stellar parameters (Teff, log g, [Fe/H], broadening velocity, radial velocity) for stars with flag_sp == 0.

Due to an error in calculating flag_fe_h for DR4, it is not meaningful as an indicator of the reliability of the derived metallicity, and should not be used. For the remaining elements, there are useful quality flags. For each indivudual elemental abundance X_fe there is a flag_X_fe that indicates problems with the elemental abundance determination. We strongly recommend only considering the abundance of element X when flag_X_fe == 0. As for all of our previous GALAH releases, we want to stress that we discourage the use of element abundances with flag_X_fe > 0 without consideration of the possible systematics that these flagged measurements can introduce.

We would recommend considering only stars with a red camera signal to noise per pixel snr_px_ccd3 > 30.

For stellar parameters and elemental abundances, use the values found in galah_dr4_allstar_240705 catalogue. We do not recommend values found only in the galah_dr4_allspec_240705 catalogue as these are meant for expert use and are typically for diagnostic purposes.

For more information, see our Table schema documentation.

  • For stellar luminosity, mass and age, we recommend lbol, mass and age in the galah_dr4_allstar_240705 catalogue.
    • These are determined by Bayesian fitting to isochrones as described in Lin et al. (2018).
  • For heliocentric distance, we recommend the r_med value, which is in the galah_dr4_allspec_240705, galah_dr4_vac_dynamics_240705, and galah_dr4_vac_wise_tmass_gaiadr3_240705 tables.
    • This matches the r_med_photogeo field from Gaia DR3 except for star clusters, where we replace it with the cluster mean distance from Cantat-Gaudin & Anders (2020) (for open clusters) or Baumgardt & Vasiliev (2021) (for globular clusters). <!—
    • distance_bstep was calculated as part of the estimation of age, mass, radius etc found in the GALAH_DR3_VAC_ages_v2 catalogue.
    • distance_bstep was used for the vast majority of stars (96 per cent) in the calculation of Galactic kinematic and dynamic parameters in GALAH_DR3_VAC_dynamics_v2. For the other 4 per cent of the stars we mostly use the photogeometric distances r_med_photogeo in the GALAH_DR3_VAC_GaiaEDR3_v2 table as calculated by Bailer-Jones et al. (2020). The distance used for a given spectrum is provided by the use_dist_flag in the GALAH_DR3_VAC_dynamics_v2 table. —>
  • For reddening, we recommend the ebv value from the galah_dr4_allstar_240705 table.
    • This is from Schlegel et al. (1998) and was used as part of the estimation of the bolometric corrections. <!—
  • Distinct from the iron abundance ([Fe/H]) calculated from the spectra, the GALAH_DR3_VAC_ages_v2 table includes the initial and current metallicity of the star (meh_ini_bstep and meh_act_bstep) as calculated by BSTEP. These values were not used as part of the abundance analysis.

This table summarizies the parameters in GALAH DR4 for which there are multiple values for a given star. We have bolded our recommended column.

| Parameter and
recommended value | main_allstar | main_allspec | VAC_ages | VAC_rv | VAC_GaiaEDR3 | | :—— |:— | :— | :—— |:— | :— | :— | | Radial velocity:
rv_galah | rv_galah,
rv_gaia_dr2 | rv_galah,
rv_gaia_dr2,
rv_guess,
rv_5854,
rv_6708,
rv_6722 | | rv_galah,
rv_sme_v2,
rv_sme_v1,
rv_obst,
rv_nogr_obst,
dr2_radial_velocity | dr2_radial_velocity | | Effective Temperature:
teff | teff,
irfm_teff | teff,
irfm_teff,
init_teff,
teff_guess | teff_bstep | | | | Surface gravity:
logg | logg | logg,
init_logg,
logg_guess | logg_bstep | | | | [Fe/H]:
fe_h | fe_h,
fe_h_atmo | fe_h,
fe_h_atmo,
init_fe_h_atmo,
feh_guess | | | | | Broadening velocity:
vbroad | vbroad | vbroad,
init_vbroad | | | | | Stellar luminosity:
log_lum_bstep | | lbol | log_lum_bstep | | | | Stellar mass:
m_act_bstep | | mass | m_act_bstep,
m_ini_bstep | | | | Stellar age:
age_bstep | | age | age_bstep | | | | Distance:
distance_bstep | r_est_dr2 | r_est_dr2 | distance_bstep | | r_med_geo,
r_med_photogeo | | E(B-V):
ebv | ebv,
irfm_ebv | ebv,
irfm_ebv | ebv_bstep | | | | Parallax | parallax_dr2 | parallax_dr2 | | | parallax,
parallax_corr | | Metallicity | | | meh_act_bstep,
meh_ini_bstep | | | —>

Joining GALAH DR4 catalogues

Join GALAH DR4 tables using the sobject_id.

The catalogues of GALAH DR4 must be joined or cross-matched using the sobject_id. The value-added catalogues are based on the extended catalogue which contains measurements per observed spectrum. 110,923 stars were observed multiple times, and therefore have multiple observed spectra. The sobject_id column is our internal ID for each observation and using this column for joining will ensure that you are matching information derived from the same spectrum.