This page describes the meaning of the standard header keywords used in released DR1 data products. These keywords appeared in the events extension, and they are copied to the primary and extension header of all data products derived from the original event file.
NAME value explanation
Column Count number of columns
Row Count number of rows
ORIGIN "MPE"
CREATOR <eSASS task>
CHOPDEAD "true", "false" records the value of the --withdeadchopper parameter of evprep (default 'yes').
For data with chopper >1, if --withdeadchopper='yes', the reduction in exposure
due to the chopper is expressed in a reduced value of the DEADTIME column in the
DEADCORn extension of the output event list; if ='no' means it is expressed
through appropriate holes in GTI
T_OFFCOR "false", "true" records the value of the --correct_times parameter of evprep (default 'no').
According to the value evprep will then correct 1-second time jumps or not
(by use of the appropriate cal file)
ERCONFIG pipeline configuration number (same as in file name)
ERVERS file version number from standard products file name
ERPREFIX first four letters/numbers of standard products file name
ERDSCODE three digit code for telescope module, filter, and energy band
(as in standard products file name)
ERDSTYPE e.g. " EventList", "Image", "ExposureMap", "BackgrImage"
as in standard products file name
OWNER "MPE", "IKI", or "MIXED"
MISSION "SRG" location of the camera
DATE file creation date (YYYY-MM-DDThh:mm:ss UT)
TELESCOP eROSITA
INSTRUME "TMn" where n is number of camera, "merged" for multi-camera event files,
NINST number of cameras in event file
INSTRUM1 e.g., TM1
...
INSTRUMn n: NINST, e.g., TM7 if NINST=7
OBS_MODE "SURVEY", "POINTING", "SLEW", or "SCAN"
DATAMODE "FRAMESTORE" (non "FRAMESTORE" data will be outside of QUALGTI)
FRAMETIM [ms] nominal frame time
FILTER "OPEN", "FILTER", "CLOSED", or "Fe55"
SKYFIELD six digit all-sky survey field number (empty for pointings)
OBS_ID obsID six digit observation ID, empty for all-sky survey
EXP_ID OBI number
OBSERVER
OBJECT name from "mission planning" (purpose oder target name, e.g.,
"Fe-K PSF", "3C 273")
RA_OBJ [deg] J2000 target coordinate of proposal
DEC_OBJ [deg] J2000 ''
RA_CEN [deg] J2000 center of all-sky surey field
DEC_CEN [deg] J2000 ''
DATE-OBS yyyy-mm-ddThh:mm:ss Start Time (UTC) of exposure
DATE-END yyyy-mm-ddThh:mm:ss End Time (UTC) of exposure
TSTART Start time of exposure in units of TIME column
TSTOP End time of exposure in units of TIME column
MJDREF 51543.875 [d] 2000-01-01T00:00:00 MSK = 51543.875 MJD
MSK=UTC+3h=MSK_actual-1
(Chandra/XMM: 1998-01-01T00:00:00)
TIMEZERO 0.0 clock correction
TIMEUNIT "s" Time unit
TIMESYS "TT" Time system (Terrestial Time)
RA_PNT [deg] actual (mean/median) pointing RA [deg] J2000
DEC_PNT [deg] actual (mean/median) pointing DEC [deg] J2000
PA_PNT mean/median position angle of pointing
RADECSYS "FK5"
EQUINOX 2000.0
TRANSMOD
PAT_THR -189 general low energy threshold [adu]
HDUCLASS
HDUVERS 1.0.0 version of format
HDUCLAS1 "EVENTS"
HDUCLAS2
SASSHIST "DATE:MMM mm hh:mm:ss YYYY HOST: hostname TASK:evprep vx.xx"
LONGSTR 'OGIP 1.0' to support multi-line COMMENT or HISTORY records
FLAGSEL event flag selection mask (written as decimal number; corresponding hex
value is placed in comment of keyword)
PAT_SEL pattern selection mask (e.g. 1: singles, 3: singles+doubles,
7: singles, doubles & triples)
GTI_SEL "GTI", "FLAREGTI", or "NONE" documents which type of GTI were applied to the data, i.e., events outside
of the given GTI type were removed from the event file
NENERGY number of energy bands selected with task `EVTOOL
EMIN1 [keV] start of energy band one
EMAX1 [keV] end of energy band one
...
EMINn [keV] start energy band n (n: NENERGY)
EMAXn [keV] end of energy band n
TTYPEi 'X '
TCTYPi 'RA---SIN' WCS Coord. type: RA tangent plane projection
TCUNIi 'deg' WCS physical unit of X axis C
TCRPXi WCS axis reference pixel
TCRVLi [deg] WCS coord. at X axis ref. pixel
TCDLTi [deg/pix] WCS X increment at ref. pixel
TLMINi Minimum for X
TLMAXi Maximum for X
TTYPEj 'Y '
TCTYPj 'DEC--SIN' WCS Coord. type: DEC tangent plane projection
TCUNIj 'deg' WCS physical unit of Y axis
TCRPXj WCS axis reference pixel
TCRVLj [deg] WCS coord. at Y axis ref. pixel
TCDLTj [deg/pix] WCS Y increment at ref. pixel
TLMINj Minimum for Y
TLMAXj Maximum for Y