The purpose of this page is to describe the meaning of the standard header key words used in event files.
It appears in events extension and is copied to the primary & extension header of all
data/products files.
ORIGIN "MPE" CREATOR <eSASS task> CONFIG pipeline configuration number (same as in file name) VERSION file version number from standard products file name PREFIX first for letters/numbers of standard products file name DSCODE three digit code for telescope module, filter, and energy band (as in standard products file name) DSTYPE e.g. " EventList", "Image", "ExposureMap", "BackgrImage" as in standard products file name OWNER "MPE", "IKI", or "IKI+MPE" MISSION "SRG" location of the camera 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 '' FIELDLON [deg] extent along ecliptic longitude and latitude FIELDLAT [deg] of field scan observations, not set otherwise DATE-OBS yyyy-mm-ddThh:mm:ss Start Time (UTC) of exposure DATE-END 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 -184 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", "QUALGTI", or "FLAREGTI" 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
REFXCTYP 'RA---SIN' WCS Coord. type: RA tangent plane projection REFXCUNI 'deg' WCS physical unit of X axis REFXCRPX WCS axis reference pixel REFXCRVL [deg] WCS coord. at X axis ref. pixel REFXCDLT [deg/pix] WCS X increment at ref. pixel REFXLMIN Minimum legal X REFXLMAX Maximum legal X REFXDMIN Minimum actual X REFXDMAX Maximum actual X REFYCTYP 'DEC--SIN' WCS Coord. type: DEC tangent plane projection REFYCUNI 'deg' WCS physical unit of X axis REFYCRPX WCS axis reference pixel REFYCRVL [deg] WCS coord. at Y axis ref. pixel REFYCDLT [deg/pix] WCS Y increment at ref. pixel REFYLMIN Minimum legal Y REFYLMAX Maximum legal Y REFYDMIN Minimum actual Y REFYDMAX Maximum actual Y
For some reason, the REFX/REFY WCS keywords don't seem to work; therefore the
more standard ones (i and j are the column numbers of the X and Y columns) are
written in instead:
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
Needed for merging survey event files from different sky maps:
RA_MIN 'deg' The non-overlapping area of RA_MAX 'deg' each sky map is defined as: DEC_MIN 'deg' ([RA_MIN,RA_MAX[,[DEC_MIN,DEC_MAX[) DEC_MAX 'deg'