The purpose of this page is to describe the column layout of eROSITA FITS source catalogues as they are generated by the eROSITA Science Analysis Software System (eSASS). The released catalogues may differ slightly from this layout and may not contain some columns as well as additional columns, which are described here.
The ERMLDET source lists contain one row per energy band and per telescope
for each source in addition to columns containing summed up results.
ID_SRC I*4 Source number
BOX_ID_SRC I*4 Source number from ERBOX input source list
ID_INST I*4 Telescope number [1…7: per telescope,
8…9: groups of telescopes
0: total]
ID_BAND I*4 Band number [1…n: band specific results,
0: total]
ID_CLUSTER I*4
ML_CTS R*4 [counts] Source counts
ML_CTS_ERR R*4 [counts] 1 sigma error
ML_CTS_LOWERR R*4 [counts] 1 sigma lower error
ML_CTS_UPERR R*4 [counts] 1 sigma upper error
X_IMA R*4 [pixels] Image pixel coordinate
X_IMA_ERR R*4 [pixels] ERMLDET error in X direction
X_IMA_LOWERR R*4 [pixels] ERMLDET lower error in X direction
X_IMA_UPERR R*4 [pixels] ERMLDET upper error in X direction
Y_IMA R*4 [pixels] Image pixel coordinate
Y_IMA_ERR R*4 [pixels] ERMLDET error in Y direction
Y_IMA_LOWERR R*4 [pixels] ERMLDET lower error in Y direction
Y_IMA_UPERR R*4 [pixels] ERMLDET upper error in Y direction
EXT R*4 [arcsec] Source extent
EXT_ERR R*4 [arcsec] 1 sigma error
EXT_LOWERR R*4 [arcsec] 1 sigma lower error
EXT_UPERR R*4 [arcsec] 1 sigma upper error
DET_LIKE R*4 Detection likelihood 1
EXT_LIKE R*4 Extent likelihood 1
ML_BKG R*4 [counts/arcmin^2] Background at source location
ML_EXP R*4 [sec] Vignetting corrected exposure at source location
ML_FLUX R*4 [erg cm^2/s] Source flux
ML_FLUX_ERR R*4 [erg cm^2/s] 1 sigma error
ML_FLUX_LOWERR R*4 [erg cm^2/s] 1 sigma lower error
ML_FLUX_UPERR R*4 [erg cm^2/s] 1 sigma upper error
ML_RATE R*4 [counts/sec] Vignetting corrected count rate
ML_RATE_ERR R*4 [counts/sec] 1 sigma error
ML_RATE_LOWERR R*4 [counts/sec] 1 sigma lower error
ML_RATE_UPERR R*4 [counts/sec] 1 sigma upper error
RA R*8 [deg] Right ascension
RA_LOWERR R*4 [arcsec] Right ascension lower error
RA_UPERR R*4 [arcsec] Right ascension upper error
DEC R*8 [deg] Declination
DEC_LOWERR R*4 [arcsec] Declination lower error
DEC_UPERR R*4 [arcsec] Declination upper error
RADEC_ERR R*4 [arcsec] Combined ERMDLET error
LII R*8 [deg] Galactic longitude
BII R*8 [deg] Galactic latitutde
ML_RADIUS R*4 [arcsec] ERMLDET source cut-out radius
MASKFRAC R*4 Fraction of extraction area within detection mask
ML_EFF R*4 Fraction of PSF inside cut-out radius
DIST_NN R*4 [arcsec] Distance to nearest neighbor
OWNER I*1 IKI/MPE sky ownership, 0: source is in MPE half of shared area, 2: source belongs to MPE
1 expressed as -ln(p) where p is the probability of the detection/the extent being due to Poissonian background fluctuations
Only for pointings in single-camera detection mode (NULL otherwise)
RAWX I*4 [pixels] Mean detector pixel position of source center
RAWY I*4 [pixels] Mean detector pixel position of source center
Only for pointings (NULL otherwise)
OFFAX R*4 [arcmin] Off-axis angle of source
VIGNET R*4 Mean Vignetting factor at source position
ONTIME R*4 [s]
Only for single-camera detection mode (NULL otherwise)
TM_NR I*1 Telescope modul number
Hardness ratios (only for different energy bands, empty otherwise)
HRn R*4 Hardness ratio between energy band n and n+1
HRn_ERR R*4 Hardness ratio error
max. 3 hardness ratios
Aperture photometry information (written by task APETOOL, NULL otherwise):
APE_CTS I*4 [counts] Counts in aperture
APE_BKG R*4 [counts] Background in aperture
APE_EXP R*4 [s] Mean exposure in aperture
APE_EEF R*4 Fraction of PSF in aperture
APE_RADIUS R*4 [pixels] Aperture radius
APE_POIS R*4 Poissonian probability of APE_CTS, given APE_BKG
The final source catalogues provide the information in the ERMLDET source lists as well as supplementary
information created by the task CATPREP and APETOOL (if it has run) in a one line
per source layout.
The columns are grouped into different sections for better legibility. The eSASS tasks
creating the information in each section are marked in brackets.
Source IDs and spatial information (ERMLDET, CATPREP):
ID_SRC I*4 Source ID from ERMLDET run
ID_CLUSTER I*4 Cluster ID from ERMLDET run
(objects which fit simultaneously have same cluster ID)
detUID C*32 Unique detection ID.
First 16 characters: same as final data products file name
Next 7 character: two caracter code of detection algorithm, followed by five digit
source number (ID_SRC from detection source list)
Last 9 characters: dataset version and processing configuration as in final
prodcuts file name
Example: em00_700001_001_ML00001_001_c010 (single eRASS, MPE owner)
OWNER I*1 IKI/MPE sky ownership, 0: source is in MPE half of shared area, 2: source belongs to MPE
RA R*8 [deg] Right ascension
RA_LOWERR R*4 [arcsec] Right ascension lower error
RA_UPERR R*4 [arcsec] Right ascension upper error
DEC R*8 [deg] Declination
DEC_LOWERR R*4 [arcsec] Declination lower error
DEC_UPERR R*4 [arcsec] Declination upper error
RADEC_ERR R*4 [sec] Combined ERMLDET positional error
LII R*8 [deg] Galactic longitude
BII R*8 [deg] Galactic latitude
DIST_NN R*4 [arcsec] Distance to nearest neighbor
SRCDENS R*4 [deg^-2] Local source density
EXT R*4 [arcsec] Source extent
EXT_ERR R*4 [arcsec] 1 sigma error
EXT_LOWERR R*4 [arcsec] 1 sigma lower error
EXT_UPERR R*4 [arcsec] 1 sigma upper error
EXT_LIKE R*4 [arcsec] Extent likelihood
ML_RADIUS R*4 [arcsec] ERMLDET source cut-out radius
MASKFRAC R*4 Fraction of extraction area within detection mask
Time range of observation (CATPREP):
TSTART R*8 [s] Start of observing interval (s/c clock)
TSTOP R*8 [s] Stop of observing interval
Hardness ratios (ERMLDET, only for different energy bands, empty otherwise):
HR_n R*4 Hardness ratio between energy band n and n+1
HR_n_ERR R*4 Hardness ratio error
with n = number of hardness ratios, maximum 3
Energy band specific information (CATPREP):
ML_CTS_n R*4 [counts] ERMLDET source counts in energy band
ML_CTS_ERR_n R*4 [counts] Source count error
ML_CTS_LOWERR_n R*4 [counts] Source count lower error
ML_CTS_UPERR_n R*4 [counts] Source count upper error
ML_RATE_n R*4 [counts/s] ERMLDET source count rate in energy band
ML_RATE_ERR_n R*4 [counts/s] Source count rate error
ML_RATE_LOWERR_n R*4 [counts/s] Source count rate lower error
ML_RATE_UPERR_n R*4 [counts/s] Source count rate upper error
ML_FLUX_n R*4 [erg/cm^2 s] Source flux derived from ML_RATE, given an energy conversion factor
ML_FLUX_ERR_n R*4 [erg/cm^2 s] Source flux error
ML_FLUX_LOWERR_n R*4 [erg/cm^2 s] Source flux lower error
ML_FLUX_UPERR_n R*4 [erg/cm^2 s] Source flux lower error
DET_LIKE_n R*4 Likelihood of detection in energy band
ML_BKG_n R*4 [counts/arcmin^2] Mean background in ERMLDET source extraction area
ML_EXP_m R*4 [sec] Mean exposure in ERMLDET source extraction area
ML_EEF_m R*4 [arcsec] Fraction of PSF in ERMLDET source cut-out radius
VIGNET_m R*4 [arcsec] Vignetting factor at source position
with n = 0...number of energy bands, 0 referring to the total band, and m = 1...number of energy bands, for each energy band
Aperture photometry information (APETOOL):
APE_CTS_m R*4 [counts] Counts in aperture
APE_BKG_m R*4 [counts] Background in aperture
APE_EXP_m R*4 [s] Mean exposure in aperture
APE_EEF_m R*4 Fraction of PSF in aperture
APE_RADIUS_m R*4 [arcsec] Aperture radius
APE_POIS_m R*4 Poissonian probability of APE_CTS, given APE_BKG
with m = 1...number of energy bands, for each energy band