ASTRA-DESI EDR Release v0.13

ASTRA-DESI Early Data Release (EDR)

This record bundles the ASTRA-DESI early data products for the 20 DESI rosettes (zones 00–19). Every catalogue is delivered as a compressed FITS binary table (.fits.gz) whose first extension (HDU 1) contains the data. File headers store the keywords RELEASE=EDR and the corresponding ZONE label for quick checks.

Tracer
Number of objects

BGS
241,746

LRG
112,649

ELG
267,345

QSO
35,566

Directory layout

The archive preserves the NERSC production tree. Top-level folders contain:

raw/ – merged real and random catalogues per zone.

classification/ – neighbour count summaries per tracer and random iteration.

probabilities/ – web-type membership probabilities derived from the classification counts.

Naming conventions

raw/zone_XX.fits.gz – zone index XX is zero-padded (00–19).

classification/zone_XX_classified.fits.gz – combined tracer summary for the zone.

probabilities/zone_XX_probability.fits.gz – per-object web-type probabilities.

Column reference

Raw catalogues (raw/*.fits.gz)

Column
Type
Description

TARGETID
int64
DESI target identifier.

RA
float64
Right ascension in degrees.

DEC
float64
Declination in degrees.

Z
float64
Spectroscopic redshift.

XCART, YCART, ZCART
float64
Comoving Cartesian coordinates (Mpc) computed with the Planck18 cosmology.

TRACERTYPE
string
Base tracer with suffix _DATA or _RAND (BGS_ANY, ELG, LRG, QSO).

RANDITER
int32
-1 for real objects, otherwise the random iteration index (0–99).

SED_SFR
float64
Star formation rate derived from SED fitting.

SED_MASS
float64
Stellar mass derived from SED fitting.

FLUX_G
float64
Observed flux in the g photometric band.

FLUX_R
float64
Observed flux in the r photometric band.

Each raw file merges all tracers for its zone. Random catalogues mirror the data counts for every tracer and random iteration. 

Additional columns SED_SFR, SED_MASS, FLUX_G, and FLUX_R were incorporated from the DESI EDR value-added catalogues associated with the emission-line sample: https://data.desi.lbl.gov/doc/releases/edr/vac/stellar-mass-emline/. These quantities are derived via SED fitting using CIGALE (Zou et al. 2024).

Classification catalogues (classification/*.fits.gz)

Column
Type
Description

TARGETID
int64
Identifier of the central object.

RANDITER
int32
-1 for data rows, otherwise the random catalogue index.

ISDATA
bool
True for data rows; False for random iterations.

NDATA
int32
Number of neighbour pairs built from data tracers for this target.

NRAND
int32
Number of neighbour pairs contributed by random tracers.

TRACERTYPE
string
Tracer family (BGS_ANY, ELG, LRG, QSO).

Probability catalogues (probabilities/*.fits.gz)

Column
Type
Description

TARGETID
int64
Identifier of the object.

TRACERTYPE
string
Tracer family.

PVOID
float32
Probability of the object being a void class.

PSHEET
float32
Probability of the sheet class.

PFILAMENT
float32
Probability of the filament class.

PKNOT
float32
Probability of the knot class.

Using the catalogues

All FITS tables are compressed with gzip.

Random catalogues use RANDITER values 0–99; filtering on RANDITER >= 0 isolates the random iterations.

The Cartesian coordinates assume the Planck18 cosmology provided by astropy.cosmology.Planck18.