The "fixtime" script requires two input files and a flag enabling update:
- The raw data file (*_raw.fits);
- The support information file (*_spt.fits).
- A "yes" or a "no" indicating whether you wish to enable updating the header
The script reads the nominal exposure time for each imset in the raw data file. From the support file it gathers the necessary information to calculate the length of time the "Take Data Flag" was down during each imset. This correction is applied to the exposure times for each imset. If you have enabled updates with a "yes" on the command line, the header of the raw data file is updated. The script prints summary information on the exposure time corrections to the screen. After running the script on the raw data file, you will need to re-run calstis in the stsdas.hst_calib.stis package in IRAF.
To use the script in IRAF, follow this example:
set ft=osfn('.')
task fixtime = ft$fixtime.cl
fixtime don1_raw.fits don1_spt.fits yes
Correcting don1_raw.fits using don1_spt.fits
Original Total Exposure Time is 2700.
Planned exposure time for imset 1 is 1349.9999993714
Exp start: 51045.92627214
TDF down: 48005.970782699
TDF up: 48005.970782699
Exp end: 51045.94189714
Corrected exposure time for imset 1 is 1349.9999993714
Planned exposure time for imset 2 is 1349.9999993714
Exp start: 51045.94240659
TDF down: 51045.94619844
TDF up: 51045.947761032
Exp end: 51045.95803159
Corrected exposure time for imset 2 is 1214.9919991381
Corrected total exposure time is 2564.9919985095