Glossary¶

Astra uses a centralized glossary system (defined in astra.glossary) to provide consistent help text for field names across all pipeline models. When a database field is created in any model, the glossary is consulted automatically to populate the field’s help_text attribute. This means that a field called teff will always carry the description “Stellar effective temperature [K]”, regardless of which pipeline produced it.

The glossary also understands naming conventions. Prefixes and suffixes like e_, raw_, and _flags are resolved automatically, so e_teff is understood as “Error on stellar effective temperature [K]” without needing a separate entry.

Naming conventions¶

Astra field names follow systematic conventions that encode meaning through prefixes and suffixes.

Prefix / Suffix	Meaning	Example
`e_`	Error (uncertainty) on a quantity	`e_teff` = error on effective temperature
`raw_`	Raw (uncalibrated) measurement	`raw_teff` = uncalibrated effective temperature
`initial_`	Initial guess value used to seed a fit	`initial_teff` = initial guess for effective temperature
`_flags`	Bitfield flags for a quantity	`result_flags` = flags describing the results
`_rchi2`	Reduced chi-square value for a fit	`nmf_rchi2` = reduced chi-square of NMF continuum fit
`rho_`	Correlation coefficient between two quantities	`rho_teff_logg` = correlation between TEFF and LOGG

These conventions are handled by the SPECIAL_CONTEXTS mechanism in the glossary module, which means that any combination (e.g., e_fe_h, raw_logg, initial_v_rad) is resolved automatically without requiring an explicit glossary entry.

Common pipeline output fields¶

These fields appear on all (or most) pipeline result tables via the PipelineOutputMixin base class.

Identifiers and metadata¶

Field	Description
`task_pk`	Task model primary key (auto-assigned unique identifier for each pipeline result)
`source_pk`	Foreign key linking to the unique source (astronomical object)
`spectrum_pk`	Foreign key linking to the unique spectrum that was analyzed
`v_astra`	Integer-encoded version of Astra that produced this result
`created`	Datetime when the task record was created
`modified`	Datetime when the task record was last modified
`tag`	Experiment tag for this result (useful for distinguishing test runs)
`t_elapsed`	Core-time elapsed on this analysis [s]
`t_overhead`	Estimated core-time spent in overheads [s]

Stellar parameters¶

These fields are produced by most stellar parameter pipelines (e.g., ASPCAP, The Cannon, The Payne, AstroNN).

Field	Description
`teff`	Stellar effective temperature [K]
`e_teff`	Error on effective temperature [K]
`logg`	Surface gravity [log10(cm/s^2)]
`e_logg`	Error on surface gravity [log10(cm/s^2)]
`fe_h`	[Fe/H] iron abundance [dex]
`e_fe_h`	Error on [Fe/H] [dex]
`m_h`	Metallicity [dex]
`v_sini`	Projected rotational velocity [km/s]
`v_micro`	Microturbulence [km/s]
`v_macro`	Macroscopic broadening [km/s]
`alpha_fe`	[alpha/Fe] abundance ratio [dex]
`c_m_atm`	Atmospheric carbon abundance [dex]
`n_m_atm`	Atmospheric nitrogen abundance [dex]
`alpha_m_atm`	[alpha/M] abundance ratio [dex]

Radial velocities¶

Field	Description
`v_rad`	Barycentric rest-frame radial velocity [km/s]
`e_v_rad`	Error on radial velocity [km/s]
`v_rel`	Relative velocity [km/s]
`bc`	Barycentric velocity correction applied [km/s]
`median_e_v_rad`	Median error in radial velocity [km/s]
`ccfwhm`	Cross-correlation function FWHM
`autofwhm`	Auto-correlation function FWHM
`n_components`	Number of components in the cross-correlation function
`v_helio`	Heliocentric velocity correction [km/s]
`v_shift`	Relative velocity shift used in stack [km/s]

Quality and fit indicators¶

Field	Description
`snr`	Signal-to-noise ratio
`result_flags`	Bitfield flags describing the results
`flag_warn`	Composite warning flag (True if any warning condition is set)
`flag_bad`	Composite bad flag (True if any critical failure condition is set)
`chi2`	Chi-square value of the fit
`rchi2`	Reduced chi-square value of the fit
`initial_flags`	Flags indicating the source of the initial guess
`calibrated`	Whether any calibration has been applied to raw measurements

Elemental abundances¶

Many pipelines (especially ASPCAP) report individual elemental abundances. These all follow the [X/H] convention in dex.

Field	Description
`al_h`	[Al/H] [dex]
`c_h`	[C/H] [dex]
`c_1_h`	[C/H] from neutral C lines [dex]
`c_12_13`	C12/C13 ratio
`ca_h`	[Ca/H] [dex]
`ce_h`	[Ce/H] [dex]
`co_h`	[Co/H] [dex]
`cr_h`	[Cr/H] [dex]
`cu_h`	[Cu/H] [dex]
`he_h`	[He/H] [dex]
`k_h`	[K/H] [dex]
`mg_h`	[Mg/H] [dex]
`mn_h`	[Mn/H] [dex]
`na_h`	[Na/H] [dex]
`nd_h`	[Nd/H] [dex]
`ni_h`	[Ni/H] [dex]
`n_h`	[N/H] [dex]
`o_h`	[O/H] [dex]
`p_h`	[P/H] [dex]
`si_h`	[Si/H] [dex]
`s_h`	[S/H] [dex]
`ti_h`	[Ti/H] [dex]
`ti_2_h`	[Ti/H] from singly ionized Ti lines [dex]
`v_h`	[V/H] [dex]

All abundance fields support the e_ prefix for uncertainties (e.g., e_al_h is the error on [Al/H]).

Spectral fields¶

These fields describe the spectral data itself, available on spectrum models (APOGEE visits/stars, BOSS spectra, etc.).

Pixel arrays¶

Field	Description
`wavelength`	Wavelength (vacuum) [Angstrom]
`flux`	Flux [10^-17 erg/s/cm^2/Angstrom]
`ivar`	Inverse variance of flux values
`e_flux`	Error on flux (computed as ivar^-0.5)
`pixel_flags`	Pixel-level quality flags (see data reduction documentation)
`model_flux`	Best-fit model flux
`continuum`	Best-fit continuum flux
`nmf_rectified_model_flux`	Rectified NMF model flux

Wavelength solution¶

Field	Description
`crval`	Reference vacuum wavelength [Angstrom]
`cdelt`	Vacuum wavelength step [Angstrom]
`crpix`	Reference pixel (1-indexed)
`npixels`	Number of pixels in the spectrum
`ctype`	Wavelength axis type
`cunit`	Wavelength axis unit
`dc_flag`	Linear (0) or logarithmic wavelength axis
`wresl`	Spectral resolution [Angstrom]

Observation metadata¶

Field	Description
`mjd`	Modified Julian Date of observation
`fiber`	Fiber number
`field`	Field identifier
`plate`	Plate number of observation
`telescope`	Telescope used to observe the source
`exptime`	Total exposure time [s]
`n_exp`	Number of co-added exposures
`nvisits`	Number of visits included in the stack
`date_obs`	Observation date (UTC)
`jd`	Julian date at mid-point of visit

BOSS-specific fields¶

Field	Description
`run2d`	BOSS data reduction pipeline version
`fieldid`	Field identifier
`plateid`	Plate identifier
`cartid`	Cartridge used for plugging
`plug_ra`	Right ascension of plug position [deg]
`plug_dec`	Declination of plug position [deg]
`zwarning`	BOSS redshift warning bitmask
`in_stack`	Whether this spectrum was used in the stack

APOGEE-specific fields¶

Field	Description
`apred`	APOGEE data reduction pipeline version
`prefix`	Short prefix used for DR17 apVisit files
`obj`	Object name
`reduction`	An `obj`-like keyword used for apo1m spectra
`n_pairs`	Number of dither pairs combined
`dithered`	Fraction of visits that were dithered
`nvisits_apstar`	Number of visits included in the apStar file
`fluxflam`	ADU to flux conversion factor [ergs/s/cm^2/A]
`n_frames`	Number of frames combined

Observing conditions¶

Field	Description
`airmass`	Mean airmass
`alt`	Telescope altitude [deg]
`az`	Telescope azimuth [deg]
`seeing`	Median seeing conditions [arcsecond]
`airtemp`	Air temperature [C]
`dewpoint`	Dew point temperature [C]
`humidity`	Humidity [%]
`pressure`	Air pressure [millibar]
`wind_speed`	Wind speed [km/s]
`wind_direction`	Wind direction [deg]
`gust_speed`	Wind gust speed [km/s]
`gust_direction`	Wind gust direction [deg]
`moon_phase_mean`	Mean phase of the moon
`moon_dist_mean`	Mean sky distance to the moon [deg]

FPS (Focal Plane System) fields¶

Field	Description
`fps`	Whether a fibre positioner was used to acquire this data
`on_target`	FPS fiber on target
`assigned`	FPS target assigned
`valid`	Valid FPS target
`fiber_offset`	Position offset applied during observations
`delta_ra`	Offset in right ascension [arcsecond]
`delta_dec`	Offset in declination [arcsecond]

Source fields¶

These fields are on the Source model, which represents a unique astronomical object.

Identifiers¶

Field	Description
`sdss_id`	SDSS-5 unique source identifier
`gaia_dr3_source_id`	Gaia DR3 source identifier
`gaia_dr2_source_id`	Gaia DR2 source identifier
`tic_v8_id`	TESS Input Catalog (v8) identifier
`catalogid`	Catalog identifier used to target the source
`catalogid21`	Catalog identifier (v21; v0.0)
`catalogid25`	Catalog identifier (v25; v0.5)
`catalogid31`	Catalog identifier (v31; v1.0)
`healpix`	HEALPix location (128 sides)
`n_associated`	Number of SDSS_IDs associated with this CATALOGID
`n_neighborhood`	Sources within 3” and G_MAG < G_MAG_source + 5

Astrometry¶

Field	Description
`ra`	Right ascension (J2000) [deg]
`dec`	Declination (J2000) [deg]
`l`	Galactic longitude [deg]
`b`	Galactic latitude [deg]
`plx`	Parallax [mas] (Gaia DR3)
`e_plx`	Error on parallax [mas] (Gaia DR3)
`pmra`	Proper motion in RA [mas/yr] (Gaia DR3)
`e_pmra`	Error on proper motion in RA [mas/yr] (Gaia DR3)
`pmde`	Proper motion in DEC [mas/yr] (Gaia DR3)
`e_pmde`	Error on proper motion in DEC [mas/yr] (Gaia DR3)
`gaia_v_rad`	Radial velocity from Gaia DR3 [km/s]
`gaia_e_v_rad`	Error on Gaia radial velocity [km/s]

Photometry¶

Field	Description
`g_mag`	Gaia DR3 mean G-band magnitude [mag]
`bp_mag`	Gaia DR3 mean BP-band magnitude [mag]
`rp_mag`	Gaia DR3 mean RP-band magnitude [mag]
`j_mag`	2MASS J-band magnitude [mag]
`e_j_mag`	Error on 2MASS J-band magnitude [mag]
`h_mag`	2MASS H-band magnitude [mag]
`e_h_mag`	Error on 2MASS H-band magnitude [mag]
`k_mag`	2MASS K-band magnitude [mag]
`e_k_mag`	Error on 2MASS K-band magnitude [mag]
`ph_qual`	2MASS photometric quality flag
`bl_flg`	Number of components fit per band (JHK)
`cc_flg`	Contamination and confusion flag

unWISE photometry¶

Field	Description
`w1_flux`	unWISE W1-band flux [Vega nMgy]
`w1_dflux`	Statistical uncertainty in W1-band flux [Vega nMgy]
`w1_frac`	Fraction of W1 flux from this object
`w2_flux`	unWISE W2-band flux [Vega nMgy]
`w2_dflux`	Statistical uncertainty in W2-band flux [Vega nMgy]
`w2_frac`	Fraction of W2 flux from this object

Extinction¶

Field	Description
`ebv`	E(B-V) reddening [mag]
`e_ebv`	Error on E(B-V) [mag]
`ebv_sfd`	E(B-V) from SFD [mag]
`ebv_zhang_2023`	E(B-V) from Zhang et al. (2023) [mag]
`ebv_bayestar_2019`	E(B-V) from Bayestar 2019 [mag]
`ebv_edenhofer_2023`	E(B-V) from Edenhofer et al. (2023) [mag]
`ebv_rjce_glimpse`	E(B-V) from RJCE GLIMPSE [mag]
`ebv_rjce_allwise`	E(B-V) from RJCE AllWISE [mag]

Distances (Bailer-Jones)¶

Field	Description
`r_med_geo`	Median geometric distance [pc]
`r_lo_geo`	16th percentile of geometric distance [pc]
`r_hi_geo`	84th percentile of geometric distance [pc]
`r_med_photogeo`	50th percentile of photogeometric distance [pc]
`r_lo_photogeo`	16th percentile of photogeometric distance [pc]
`r_hi_photogeo`	84th percentile of photogeometric distance [pc]

Targeting¶

Field	Description
`lead`	Lead catalog used for cross-match
`version_id`	SDSS catalog version for targeting
`carton_0`	First carton for the source
`carton_flags`	Carton bit field
`sdss5_target_flags`	SDSS-5 targeting flags

Data reduction pipeline version fields¶

Various version fields track the software used in data processing.

Field	Description
`v_astra`	Astra version (integer-encoded)
`v_apred`	APOGEE data reduction pipeline version
`v_boss`	Version of the BOSS ICC
`v_jaeger`	Version of Jaeger
`v_kaiju`	Version of Kaiju
`v_coord`	Version of coordIO
`v_calibs`	Version of FPS calibrations
`v_read`	Version of idlspec2d for processing raw data
`v_2d`	Version of idlspec2d for 2D reduction
`v_comb`	Version of idlspec2d for combining exposures
`release`	The SDSS release name