DOI: 10.5281/zenodo.17299147
title: ASTRA-DESI DR1 Release v0.5

description: ASTRA-DESI Data Release 1 (DR1)

This record bundles the ASTRA-DESI DR1 products for the two DESI survey regions (NGC1 and NGC2). 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=DR1 and the corresponding ZONE label for quick checks.

The regions follow the sky boxes defined by Hou et al. (2025, arXiv:2508.09070):



NGC1 covers 110 ° ≤ RA ≤ 260 ° and -10 ° ≤ DEC ≤ 8 °;

NGC2 covers 180 ° ≤ RA ≤ 260 ° and 30 ° ≤ DEC ≤ 40 °.





Tracer
Number of objects




BGS
240,986


LRG
102,199


ELG
67,456


QSO
87,307




Directory layout

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



raw/ – merged real and random catalogues per region.

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

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

pairs/ – sparse list of target pairs used when counting neighbours.

groups/ – FoF group catalogues for objects classified as filaments and voids.


Naming conventions



raw/zone_REGION.fits.gz – Region NGC1 or NGC2.

classification/zone_REGION_classified.fits.gz – combined tracer summary for the region.

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

pairs/zone_REGION_pairs.fits.gz – neighbour pairs for the region.

groups/zone_REGION_groups_fof_filament.fits.gz – filament FoF groups restricted to data targets for all iterations per region.

groups/zone_REGION_groups_fof_void.fits.gz – void FoF groups for all random iterations per region.


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
Tracer label with suffix _DATA or _RAND (BGS_BRIGHT, ELG, LRG, QSO).


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




Random catalogues mirror the data counts for every tracer and random iteration.

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_BRIGHT, 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.




Pair catalogues (pairs/*.fits.gz)




Column
Type
Description




TARGETID1
int64
Central object in the neighbour pair.


TARGETID2
int64
Neighbour contributing to the count.


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




Group catalogues (groups/*.fits.gz)




Column
Type
Description




TRACERTYPE
string
Tracer family.


TARGETID
int64
Member identifier.


RANDITER
int32
Random iteration index.


WEBTYPE
string
Cosmic web class.


GROUPID
int32
FoF group label unique within each region.


NPTS
int32
Number of members in the group.


XCM, YCM, ZCM
float64
Group barycentre in comoving Cartesian coordinates (Mpc).


A, B, C
float64
Semi-axis lengths of the inertia ellipsoid (Mpc) ordered A≥B≥C.


LINKLEN
float64
FoF linking length.


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




The group finder is executed separately for each tracer. The linking length is computed per tracer and iteration as the cube root of the convex-hull volume per galaxy.

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.