eSASS task: evatt

Scope

Summary:

The task EVATT calculates equatorial sky coordinates for each event based on the detector coordinates of the event, the attitude data at the time of the event and the boresight calibration information in the camera specific instpar calibration file.

Algorithms:

Read photon event list from extension 'EVENTS' in file eventfile . The camera specific (corrected) attitude time series is read from extension CORRATTn of the input attitude file ( attfile ), GTIs are read from extension GTIn (n=telescope ID) of file gtifile. Typically the attitude and GTI tables will be extensions of the event file ( eventfile = attfile = gtifile ). The task checks whether the attitude is sufficiently sampled in the GTI intervals, (Δt < 90 sec), otherwise a warning is issued. The attitude data from the telescope specific CORRATT table are interpolated to the time of the photon event. Using the detector coordinates of the event (columns RAWX, RAWY, SUBX, SUBY) , the boresight and platescale information from the instpar calibration file for the telecope module, and the attitude data, the event position is projected to equatorial sky coordinates and written to the columns RA and DEC of the events table. The task also calculates galactic coordinates for each photon and writes the sky ownership flag (column FLAG): owner=MPE=> bit0=0, owner=IKI=> bit1=0, MPE+IKI: bit0=0.and.bit1=0

The task reads the TIMELAG value from the camera specific INSTPAR calibration file in order to correct for timing offsets between the times in the CORRATT and EVENTS extensions. Note that from pipeline version 946 the varying 1 sec time jumps are corrected in the event list by task evprep. Therefore new INSTPAR calibration files (currently version number 15) have been prepared, which are to be used with data processed by pipeline version 946 or higher. In these data the keyword T_OFFCORR='T' should be present. The version of the INSTPAR files in this case cannot be set automatically by the CALDB, but can be selected by using a CALVERS file. Event files processed by older pipeline versions have to be processed using versions of the INSTPAR calibration file below v15. These are selected by the CALDB by default.

Note that only event files containing data from a single telescope module can be processed by EVATT.

Parameters:

• eventfile (string) OPTIONAL [e.g. events.fits]
  • Input event file
  • Only files containing events from a single telescope module are accepted.
• attfile (string) OPTIONAL [e.g. attitude.fits]
  • Input file with corrected attitude table (extension CORRATTn)
• gtifile (string) OPTIONAL [e.g. gti.fits]
  • Input file with GTI table (extension GTIn)

Input files:

• Event file

  File name defined by parameter eventfile.

• attfile Telescope specific attitude file or event file with CORRATTn extension.
• gtifile GTI file or event file with GTIn extension.

Output files:

• Event file Same es input event file eventfile. The equatorial coordinates calculated by EVATT are written to the RA,DEC columns of the EVENTS extension. The ownership bits of column FLAG in extension EVENTS are updated.

evatt eventfile="e_1_46085_001_c946.fits" \
      attfile="e_1_46085_001_c946.fits" \
      gtifile="e_1_46085_001_c946.fits"