Back to main eRASS1 catalogues page

Data Model: eRASS1_clusters_optical

General description
Optical properties of the eRASS1 clusters and groups, as described in Kluge et al. (2024; submitted). The catalog contains eRASS1 extended X-ray sources (EXT_LIKE>3) from Bulbul et al. (2024) for which the optical properties (e.g., redshift, richness) are measured using optical and near-infrared data from the Legacy Surveys.

Filename:
eRASS1_clusters_optical.fits

Approximate size
4 MB

File type
FITS

Generated by product
eSASS, eROMaPPer

Sections

Content of the page (HDU means "Header Data Unit" of a fits file).

HDU0: PRIMARY

empty HDU

HDU Type
IMAGE
HDU Size
0 bytes

HDU1: CATALOG

This is the main content of the catalog.

HDU Type
BINARY TABLE
HDU Size
4 MB
NameTypeUnitDescription
NAME char[23] None Cluster name
DETUID char[32] None Unique eSASS detection ID
RA float32[E4] deg Right Ascension J2000 of X-ray prior
DEC float32[E5] deg Declination J2000 of X-ray prior
RADEC_ERR float32[E2] arcsec Uncertainty of RA, DEC (arcsec)
RA_OPT float32[E4] deg Right Ascension J2000 of optical center
DEC_OPT float32[E5] deg Declination J2000 of optical center
RA_BCG float32[E4] deg Right Ascension J2000 of the brightest member
DEC_BCG float32[E5] deg Declination J2000 of the brightest member
REFMAG_BCG float32[E3] z mag galactic extinction-corrected z-band AB magnitude of the brightest member
BEST_Z float32[E5] None Best available cluster redshift
BEST_Z_ERR float32[E5] None Error on best available cluster redshift
BEST_Z_TYPE char[16] None Type of best available cluster redshift
Z_LAMBDA float32[E5] None Uncorrected cluster photometric redshift
Z_LAMBDA_ERR float32[E5] None Uncorrected cluster photometric redshift uncertainty
Z_LAMBDA_CORR float32[E5] None Bias-corrected cluster photometric redshift
Z_LAMBDA_CORR_UERR float32[E5] None Bias-corrected cluster photometric redshift upper error
Z_LAMBDA_CORR_LERR float32[E5] None Bias-corrected cluster photometric redshift lower error
Z_LAMBDA_SECOND float32[E5] None Uncorrected foreground/background cluster photometric redshift
LIT_Z float32[E5] None Literature cluster redshift
LIT_Z_ERR float32[E5] None Literature cluster redshift error
LIT_Z_SRC char[32] None Reference for lit_z
SPEC_Z_BOOT float32[E5] None Bootstrap estimate of biweight spectroscopic redshift
SPEC_Z_BOOT_ERR float32[E5] None Bootstrap error on biweight spectroscopic redshift
N_MEMBERS int32 None Number of members used in biweight redshift and velocity dispersion estimate
CG_SPEC_Z float32[E5] None Spectroscopic redshift of the central galaxy
CG_SPEC_Z_ERR float32[E5] None Error on spectroscopic redshift of the central galaxy
BCG_SPEC_Z float32[E5] None Spectroscopic redshift of the brightest member
VDISP_BOOT float32[E2] km s-1 Bootstrap estimate of velocity dispersion (km/s)
VDISP_BOOT_ERR float32[E2] km s-1 Error on bootstrap estimate of velocity dispersion (km/s)
VDISP_BOOT_FLAG float32[E2] None Fraction of diverged velocity clippings
VDISP_TYPE char[8] None Estimate used to determine vdisp. Gapper or Biweight depending on number of members
LAMBDA_NORM float32[E2] None Richness normalized to the the definition of the grz run
LAMBDA_NORM_ERR float32[E2] None Richness error normalized to the definition of the grz run
LAMBDA_OPT_NORM float32[E2] None Richness (optical center) normalized to the definition of the grz run
LAMBDA_OPT_NORM_ERR float32[E2] None Richness (optical center) error normalized to the definition of the grz run
SCALEVAL float32[E5] None Richness scale factor Eq. 2 of Rykoff 2016
MASKFRAC float32[E3] None Fraction of cluster area which is masked
RUN char[128] None RedMaPPer calibration: survey_bands_refband_iteration
LMAX float32[E4] None Optical maximum likelihood
NHI float32[E5] 1021 cm-2 HI Column Desnsity (10^21 cm^-2) from HI4PI. Nside=1024
EXT_LIKE float32[E5] None Extent likelihood of the X-ray source
PCONT float32[E4] None Probability that the cluster is a contaminant
SHARED_MEMBERS bool None There is another cluster with >=70% of the same members and higher LMAX
IN_FOOTPRINT bool None Cluster is within the optical survey footprint
LIMMAG_G float32[E2] g mag Limiting g galaxy magnitude from Rykoff+15 depth (map) model
LIMMAG_R float32[E2] r mag Limiting r galaxy magnitude from Rykoff+15 depth (map) model
LIMMAG_I float32[E2] i mag Limiting i galaxy magnitude from Rykoff+15 depth (map) model
LIMMAG_Z float32[E2] z mag Limiting z galaxy magnitude from Rykoff+15 depth (map) model
LIMMAG_W1 float32[E2] W1 mag Limiting w1 galaxy magnitude from Rykoff+15 depth (map) model
IN_ZVLIM bool None Photometric redshift is smaller than the limiting optical survey redshift ZVLIM_02 or ZVLIM_04
ZVLIM_02 float32[E3] None Maximum observable galaxy redshift at 0.2L* volume limit
ZVLIM_04 float32[E3] None Maximum observable galaxy redshift at 0.4L* volume limit
GAIA_10MAG_30_ARCSEC bool None A star in the GAIA eDR3 catalog brighter than 10 G mag is closer than 30 arcsec to the X-ray source
NGC_30_ARCSEC bool None A galaxy in the NGC catalog is closer than 30 arcsec to the X-ray source
HECATE_30_ARCSEC bool None A galaxy in the HECATE survey is closer than 30 arcsec to the X-ray source

References

Kluge, M., et al., The First SRG/eROSITA All-Sky Survey: Optical Identification and Properties of Galaxy Clusters and Groups in the Western Galactic Hemisphere, A&A, 688, A210 (2024)

Bulbul, E., et al., The SRG/eROSITA All-Sky Survey: The first catalog of galaxy clusters and groups in the Western Galactic Hemisphere, A&A, 685A, 106 (2024)

Merloni, A., et al., The SRG/eROSITA All-Sky Survey: First X-ray catalogues and data release of the western Galactic hemisphere, A&A, 682, A34 (2024)

Legacy Surveys, The optical in near-infrared data used in this work

eRASS Cluster Inspector, Interactive tool to inspect the cluster catalogs

Acknowledgement

This work is based on data from eROSITA, the soft X-ray instrument aboard SRG, a joint Russian-German science mission supported by the Russian Space Agency (Roskosmos), in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI), and the Deutsches Zentrum für Luft und Raumfahrt (DLR). The SRG spacecraft was built by Lavochkin Association (NPOL) and its subcontractors and is operated by NPOL with support from the Max Planck Institute for Extraterrestrial Physics (MPE). The development and construction of the eROSITA X-ray instrument was led by MPE, with contributions from the Dr. Karl Remeis Observatory Bamberg & ECAP (FAU Erlangen-Nuernberg), the University of Hamburg Observatory, the Leibniz Institute for Astrophysics Potsdam (AIP), and the Institute for Astronomy and Astrophysics of the University of Tübingen, with the support of DLR and the Max Planck Society. The Argelander Institute for Astronomy of the University of Bonn and the Ludwig Maximilians Universität Munich also participated in the science preparation for eROSITA. The eROSITA data shown here were processed using the eSASS software system developed by the German eROSITA consortium.
The Legacy Surveys consist of three individual and complementary projects: the Dark Energy Camera Legacy Survey (DECaLS; Proposal ID #2014B-0404; PIs: David Schlegel and Arjun Dey), the Beijing-Arizona Sky Survey (BASS; NOAO Prop. ID #2015A-0801; PIs: Zhou Xu and Xiaohui Fan), and the Mayall z-band Legacy Survey (MzLS; Prop. ID #2016A-0453; PI: Arjun Dey). DECaLS, BASS and MzLS together include data obtained, respectively, at the Blanco telescope, Cerro Tololo Inter-American Observatory, NSF’s NOIRLab; the Bok telescope, Steward Observatory, University of Arizona; and the Mayall telescope, Kitt Peak National Observatory, NOIRLab. Pipeline processing and analyses of the data were supported by NOIRLab and the Lawrence Berkeley National Laboratory (LBNL). The Legacy Survey team makes use of data products from the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), which is a project of the Jet Propulsion Laboratory/California Institute of Technology. NEOWISE is funded by the National Aeronautics and Space Administration.