The purpose of this page is to describe the structure of an event file and its extensions as it is produced by the eROSITA Science Analysis Software System (eSASS) .
On this page
The baseline will be separate event files for each camera containing, one EVENTS extension plus
additional camera specific extensions, defined in this file. In order to allow straightforward
merging of the event files from different cameras, a column TM_NR is included in the EVENTS
extension to keep track of the origin of each event after merging the camera specific EVENTS
extensions. All other camera specific extensions will have the camera number as the last digit of
their extension name. They will thus still have unique names after copying them into an all camera event file.
There are different event files which can have more or fewer columns depending on whether it is a
raw event file, an event file assigned to an eROday or a sky tile. Raw event files
will not be discussed here, because they are not part of the EDR.
Most users will have to deal with event files assigned to a sky tile.
Columns of event files assigned to eROdays are marked with 'I', and those of event files assigned
columns are marked by 'C'. Also, see the section on the order of the event file columns.
TIME R*8 CI as defined in MJDREF, TIMEZER, TIMEUNIT keywords;
by default, the TIME values will be non-randomized and not
baricentre-corrected; these corrections will be applied by
interactive tasks on a case by case basis
RA, DEC I*4 CI J2000, unit: 10-6 deg (FITS keywords TZEROn=0.D0 TSCALn = 1.D-6)
calculated from attitude, RAWX, RAWY, and SUBX, SUBY
X, Y I*4 CI sky coordinates (calculated from RA, DEC)
pixel size 0.05''; units and origin as defined
in WCS keywords
PI R*4 CI calibrated and recombined amplitude [eV]
For each pixel of a pattern (all sizes, also MIPS),
the PI column will contain the corrected total energy
(positive for main event, negativ for all other
pixels); the corrected amplitudes for the individual
pixels are written in the columns AMP_GAIN and
AMP_COR (not included in standard products event files).
EV_WEIGHT R*4 CI contains invers vignetting correction factor
(and potentially other corrections)
RAWX, RAWY I*2 CI as defined in Properties of the CCDs relevant for processing
SUBX, SUBY I*1 CI as defined in Properties of the CCDs relevant for processing
PHA I*2 CI raw amplitude [adu]
PAT_TYP I*2 CI pattern type: number of pixels in the pattern,
positive (1-4) for valid, negative for invalid patterns,
same value for all the pixels in the pattern,
0 indicates that pixel was ignored because PHA was too low
PAT_INF I*1 CI pattern information:
for valid patterns: 3 decimal digits p d q
p: position of the pixel in the pattern (0-2)
d: direction of the pattern (1-4)
q: quality of the pattern (0-9)
for single pixels: tr q
tr: trailing pixel info: precursor distance (<26)
q: quality, with additional information about diagonal pixel(s)
for invalid patterns:
number of pixels with MIP-like PHAs
TM_NR I*1 CI 1-7 for eROSITA telescope modules
FLAG I*4 CI flag 0...1: owner flags
flag 4...11: information flags
flag 12...30: rejection flags
see description below
FRAMETIME CI Time of the frame
RECORDTIME CI high resolution creation time of the record
PAT_IND I*2 I pattern index: running number counting within each
readout frame the patterns which are larger than one pixel,
positive for main pixel, negative for the others;
for single pixels: precursor distance
(PAT_IND is only needed as a temporary column)
AMP_GAIN I contains the gain corrected pulse height amplitude for the
individual pixel (i.e., before any pattern recombination)
AMP_COR I contains the gain and CTI corrected pulse height amplitude
for the individual pixel (i.e., before any pattern recombination)
Order of calibrated event file columns (as archived in the products archive)
This is the standard order of the columns as created by the eSASS pipeline (software
reading the event files is expected to work with any ordering of the columns).
| Name | Type | Bytes (cumulative) |
|---|---|---|
TIME | R*8 | 8 |
RA, DEC | R*8 | 24 |
X, Y | R*8 | 40 |
PI | R*4 | 44 |
EV_WEIGHT | R*4 | 48 |
RAWX, RAWY | I*2 | 52 |
SUBX, SUBY | R*8 | 68 |
PHA | I*2 | 70 |
PAT_TYP | I*2 | 72 |
PAT_INF | Byte | 73 |
TM_NR | Byte | 74 |
FLAG | I*4 | 78 |
FRAMETIME | R*8 | 86 |
RECORDTIME | R*8 | 94 |
| # | HEX | Name | written by task |
|---|---|---|---|
| Owner flags: | |||
| 0 | 0x1 | MPE_OWNER | EVATT (0: MPE is owner) |
| 1 | 0x2 | IKI_OWNER | EVATT (0: IKI is owner) |
| Information flags: | |||
| 4 | 0x10 | TRAILING_EVENT | PATTERN |
| 5 | 0x20 | NEXT_TO_BORDER | EVPREP |
| 8 | 0x100 | NEXT_TO_ONBOARD_BADPIX | FTFINDHOTPIX |
| 9 | 0x200 | NEXT_TO_BRIGHT_PIX | FTFINDHOTPIX |
| 10 | 0x400 | NEXT_TO_DEAD_PIX | FTFINDHOTPIX |
| 11 | 0x800 | NEXT_TO_FLICKERING | FTIFNDHOTPIX |
| Rejection flags: | |||
| 12 | 0x1000 | ON_FLICKERING | FTFINDHOTPIX |
| 13 | 0x2000 | ON_BADPIX | FTFINDHTOPIX |
| 14 | 0x4000 | ON_DEADPIX | FTFINDHOTPIX |
| 15 | 0x8000 | OUT_OF_FOV | EVPREP |
| 16 | 0x10000 | OUTSIDE_QUALGTI | QUALGTI |
| 17 | 0x20000 | OUTSIDE_GTI | EVPREP |
| 18 | 0x40000 | PRECEDING_MIP | EVPREP |
| 19 | 0x80000 | MIP_ASSOCIATED | EXPOSURE |
| Quality flags: | |||
| 24 | 0x1000000 | PHA_QUALITY_1 | EVPREP |
| 25 | 0x2000000 | PHA_QUALITY_2 | EVPREP |
| 26 | 0x4000000 | PHA_QUALITY_3 | EVPREP |
| Corrupted data: | |||
| 30 | 0x40000000 | CORRUPT_EVENT | EVPREP |
| 31 | 0x80000000 | CORRUPT_FRAME | EVPREP |
EXTNAME 'EVENTS ' Name of FITS table extension
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0. '
HDUCLAS1 'EVENTS '
HDUCLAS2 ' '
GTI data, created by the preprocessor. The GTI extension should at all times reflect the actual
events contained in the EVENTS extension. It thus needs to be updated whenever a temporal
(survey and pointing) or spatial (survey) selection has been performed on the EVENTS extension.
Table columns:
START R*8 start and stop times of good time intervals;
STOP R*8 times as defined in TIME column of EVENTS extension
Header keywords:
EXTNAME 'GTIn ' n: number of camera (as in CCDNR column of EVENTS extension)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0. '
HDUCLAS1 'EVENTS '
HDUCLAS2 ' '
Flare GTI, computed by task FLAREGTI (same format as GTIn)
Quality GTI, created by task MKFILTER (same format as GTIn)
Table columns:
TIME R*8 times as defined in TIME column of EVENTS extension
RA R*8 RA [deg] of optical axis of telescope n
DEC R*8 DEC [deg] of optical axis of telescope n
ROLL R*8 roll angle (assumed to be the counter-clockwise
angle between the north direction in the J2000 coordinate
system and the X direction of the RAWX/RAWY coordinate system;
note that the north direction is assumed to be the real north
direction and not the projection of the north vector through
the telescope on the detector.
Header keywords:
EXTNAME 'CORRATTn' n: number of camera (as in CCDNR column of EVENTS extensions)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0. '
HDUCLAS1 'EVENTS '
HDUCLAS2 ' '
Table columns:
TIME R*8 times as defined in TIME column of EVENTS extension
(time refers to middle of valitidty interval)
DEADC R*4 0...1 (livetime/ontime); corresponds to
FRACEXP column of XMM EXPOSURE extensions
or FCT of SASS file LFTIMX)
Header keywords:
EXTNAME 'DEADCORn' n: number of camera (as in CCDNR column of EVENTS extension)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0. '
HDUCLAS1 'EVENTS '
HDUCLAS2 ' '
Table columns:
Name Format Description
RAWX I*2 detector pixel coord
RAWY I*2 detector pixel coord
YEXTENT I*2 extend of bad column in y direction
TYPE I*2 1=Hot; 2=Flickering; 3=Dead etc.
BADFLAG I*2 1=uplinked; 2=from CALDB; 3=from file etc.
TIMEMIN R*8 Start of time window in which pixel is bad
TIMEMAX R*8 End of time window in which pixel is bad
PHAMAX I*2 Upper bound of the PHA range over which pixel is bad
PHAMIN I*2 Lower bound of the PHA range over which pixel is bad
PHAMED R*4 Median of PHA vbalues (optional)
Header keywords:
EXTNAME 'BADPIXn' n: number of camera (as in CCDNR column of EVENTS extension)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0. '
HDUCLAS1 'EVENTS '
HDUCLAS2 ' '
Contains HK quantities copied from HK files, needed by eSASS tasks
Table columns:
TIME R*8 times as defined in TIME column of EVENTS extension
PnPROCMODE Byte processing mode; 0: IDLE, 1: work mode, 2: calc offset, 3: calc noise,
4: all singles, ... , 9: environment mode 1, 10: environment mode
PnSEQMODE Byte sequencer mode, 08:idle, 0A: workmode - framestore, ...
PnSCTSTAT Byte timesynchronisation between CE and onboard-timesource; 5: synchronous, 7: asynchronous, ...
PnPROCOPTS I*4 options for program control; 1: always send frame times, ...
PnTMFRAMES R*4 telemetry frame counter
PnCCDFRAMES R*4 number of processed CCD frames
PnEVTCTR R*4 event counter
PnMIPCTR R*4 MIP counter (number of pixels affected by MIP))
PnFWSTEPCT R*4 step counter (executed)
PnFWSTAT Byte status of filter wheel
PnCHOPPER R*4 specifies what number CCD frame should be processed
Recordtime R*8 high resolution creation time of the record
PnSPLT2NOI R*4 split to noise ratio
PxEVTQLIMT R*4 event quota limit
RFRAMETIME R*8
QRFRAMETIME I*2
DnPROCMODE I*2
DnPROCOPTS I*2
DnFWSTAT I*2
DETSTAT I*2
Header keywords:
EXTNAME 'HKn1 ' n: number of camera (as in CCDNR column of EVENTS extensions)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0.'
HDUCLAS1 'EVENTS'
HDUCLAS2 ' '
Table columns:
TIME R*8 times as defined in TIME column of EVENTS extension
FWHEEL Byte position of filter wheel; 0: closed, 1: open, 2: filter, 3: calibration
CnFWPOS Byte position of filter wheel; 8: filter, 12: open, 13: calibration, 14: closed, 15: moving
CnHVFWSW Byte switches for HV, filter wheel converter and filterwheel position sensors
CnSTPVOLT R*4 voltage of stepper motor
PnMIPDELN R*4 MIP deletion area to the north
PnMIPDELS R*4 MIP deletion area to the south
PnMIPDELOW R*4 MIP deletion area to the east and west
PnMIPIMGMX Byte MIP image (time exposure) maximum
Recordtime R*8 high resolution creation time of the record
DnFWPOS I*2
RFRAMETIME R*8
QRFRAMETIME I*2
Header keywords:
EXTNAME 'HKn2 ' n: number of camera (as in CCDNR column of EVENTS extensions)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0.'
HDUCLAS1 'EVENTS'
HDUCLAS2 ' '
Table columns:
TIME R*8 times as defined in TIME column of EVENTS extension
PnFWDELAY R*4 overshoot
PnENVTAB R*4 table index for selected ENV (dynamic pair))
DnENVTAB I*2
Recordtime R*8 high resolution creation time of the record
RFRAMETIME R*8
QRFRAMETIME I*2
Header keywords:
EXTNAME 'HKn3 ' n: number of camera (as in CCDNR column of EVENTS extensions)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0.'
HDUCLAS1 'EVENTS'
HDUCLAS2 ' '
Table columns:
TIME R*8 times as defined in TIME column of EVENTS extension
PnMIPTHR R*4 data processing, mip threshold
PnPRIMTHR R*4 data processing, prime threshold
PnFWSTEPS R*4 number of steps til next stop
PnSPLTCT R*4 slit event counter
PnEVTBMAX R*4 event-R/P filling level maximum
PnOUTBFREE R*4 output R/P: free places
Recordtime R*8 high resolution creation time of the record
PnMIPCRTPT R*4
DnMIPTHR I*2
DnPRIMTHR I*2
DnMIPCTRPT I*2
RFRAMETIME R*8
QRFRAMETIME I*2
Header keywords:
EXTNAME 'HKn5 ' n: number of camera (as in CCDNR column of EVENTS extensions)
HDUCLASS ' ' Type/source of format
HDUVERS '1.0.0.'
HDUCLAS1 'EVENTS'
HDUCLAS2 ' '
Documents spacial selections by tasks EVTOOL and SRCTOOL.
Table columns:
SHAPE A*16 shape of region: circle, rectangle, ellipse, box
XC R*8 x coordinate of center in degrees
YC R*8 y coordinate of center in degrees
R R*8 size of region in degrees
ROTANG R*8 rotation angle
This procedure is implemented in the task EVTOOL (see 2.2 in the eSASS cookbook).
Several operations are done by EVTOOL