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.
