DOI: 10.5281/zenodo.17299085
title: ASTRA-DESI EDR Release v0.5

description: 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.

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_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.

pairs/zone_XX_pairs.fits.gz – neighbour pairs for the zone.

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

groups/zone_XX_groups_fof_void.fits.gz – void FoF groups for all random iterations per zone.


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).




Each raw file merges all tracers for its zone. 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_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.




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 (zone, tracer).


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.