ETACHAHARD - Eta Chamaeleontis eROSITA EDR Field X-Ray (2.3-5.0 keV) Source Catalog
The nearby young open cluster eta Chamaeleontis was observed by eROSITA/SRG during its CalPV phase for 150 ks. The eROSITA data were taken in the field-scan mode, an observing mode of Spectrum-Roentgen-Gamma (SRG) that follows a rectangular grid-like pattern, covering a 5x5 deg field with an exposure depth of about 5 ks. The authors studied the known members in X-rays and searched for potential new members of the anticipated dispersed low-mass cluster population. Detected sources were identified by cross-matching X-ray sources with Gaia and 2MASS, and young stars were identified by their X-ray activity, by their position in the color-magnitude diagram, and by their astrometric and kinematic properties. X-ray luminosities, light curves, and spectra of cluster members were obtained and compared with previous X-ray data. Literature results of other member searches were used to verify the new member candidates in the observed field.
The authors determined X-ray properties of virtually all known eta Cha members and identified five additional stellar systems that showed basically identical characteristics, but are more dispersed. Four of them were previously proposed as potential members; this status is supported by this X-ray study. Based on their spatial distribution, further members are expected beyond the sky region surveyed. The identified stellar systems very likely belong to the ejected halo population, which brings the total number of eta Cha cluster members to at least 23.
ETACHAMAIN is the related catalog of main (0.2-2.3 keV) sources.
Robrade et al. (2022), "eROSITA X-ray scan of the eta Chamaeleontis cluster. Member study and search for dispersed low-mass stars", <A&A, 661, A34 (2022)> =2022A&A...661A..34R
The IAU-style J2000 position-based source designation, e.g., 'SRGE JHHMMSS.s+DDMMSS'. [ERO_NAME]
The unique, sequential identification number for each source in this catalog. [ID_SRC]
The right ascension of the source in the selected equinox. This was given in J2000 decimal degree coordinates to an accuracy of 10-5 degrees (0.036 arcseconds) in the original reference.
The declination of the source in the selected equinox. This was given in J2000 decimal degree coordinates to an accuracy of 10-6 degrees (0.0036 arcseconds) in the original reference.
The Galactic longitude of the source.
The Galactic latitude of the source.
The uncertainty in the position, in arcseconds, based on the combined uncertainties in the ra and dec coordinates. [RADEC_ERR]
The extent of the source, given in arcseconds. Values of 0.0 indicate point sources. [EXT]
The uncertainty in the extent of the source, given in arcseconds. Values of 0.0 indicate point sources. [EXT_ERR]
The likelihood associated with the extent measurement. Values of 0.0 indicate point sources. [EXT_LIKE]
Background-subtracted 2.3-5.0 keV net counts for the source, based on PSF-fitting. [ML_CTS]
The 1-sigma uncertainty in the 2.3-5.0 keV net counts. [ML_CTS_ERR]
The net count rate for the source in the 2.3-5.0 keV band, based on PSF-fitting. [ML_RATE]
The 1-sigma uncertainty in the 2.3-5.0 keV net count rate. [ML_RATE_ERR]
The flux of the source in the 2.3-5.0 keV band, in units of erg/s/cm2. [ML_FLUX]
The 1-sigma uncertainty in the 2.3-5.0 keV flux, in units of erg/s/cm2. [ML_FLUX_ERR]
The detection likelihood in the 2.3-5.0 keV band. [DET_LIKE]
The background counts, in units of counts/arcmin2, at the source position in the 2.3-5.0 keV band. [ML_BKG]