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:
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