NAME
ixpedet2j2000 -- Transforms IXPE event positions and Stokes parameters from detector to sky coordinates.
USAGE
ixpedet2j2000.py infile outfile attfile_in [align] [teldef] [sc] [clobber]
DESCRIPTION
ixpedet2j2000 converts DETX, DETY detector coordinates and Stokes parameters DETQ and DETU of events contained in an existing Level 1 IXPE event FITS file (infile) to X, Y sky coordinates and Q, U oriented along declination (+Q) and position angle (+U along position angle +45 degrees) and adds these new columns, along with all original Level 1 event file columns, to a new FITS file (outfile). Optionally, event positions in spacecraft coordinates can also be added to the output event FITS file (sc=true).
ixpedet2j2000 uses the event time stamp from the Level 1 event list and the rotation quaternions from a Level 1 attitude file (attitude) to perform this transformation. The quaternions are calculated by combining time-independent quaternions representing detector frame to the focal plane frame, focal plane frame to the spacecraft frame, and spacecraft frame to star tracker optical head with the time-varying quaternions produced by the star tracker, which rotate from the star tracker optical head frame to the J2000 sky frame. The latter quaternions are generated at a rate of 10 Hz. The transformation quaternion is found by linearly interpolating between the two attitude solutions which bracket the event time component-by-component.
PARAMETERS
- infile* (str)
- Input FITS Event file.
- outfile* (str)
- Output file name.
- attfile_in* (str)
- FITS Attitude file corresponding to input Event file.
- align
- Path to the spacecraft alignment CALDB file (default: caldb)
- teldef
- Path to the teldef CALDB file (default: caldb)
- sc
- Append column of event locations in spacecraft coordinates? (default: no)
- clobber
- Overwrite existing output file? (default: no)
EXAMPLES
BUGS
SEE ALSO
LAST MODIFIED
Feb 2022