ldeadtime -- Carry out deadtime correction for FITS light curves.
ldeadtime lcfile mkffile
LDEADTIME calculates live time fraction for each light-curve bin in a FITS light curve (lcfile) based on deadtime values given in the MKFILTER file (mkffile). This task was primarily written for ASCA GIS, but may be used for similar instruments. LDEADTIME fills the 'FRACEXP' fractional exposure column, whose value is the live-time fraction for each time-bin. These values are originally one when the lcfile is created with xselect/extractor without the deadtime correction. After the deadtime correction with LDEADTIME, FRACEXP takes values between zero and one. New RATE and ERROR values are calculated by dividing original values by FRACEXP, and these columns are overwritten.
Since the lcfile is updated it would be prudent to make a copy of the input lcfile before running this task, in the event that it does not complete successfully and leaves the file in a corrupted state.
The details of the ASCA GIS 'deadtime' fraction calculation procedure is given in the MKDTIME task description.
If any FRACEXP values are zero (this should not happen), warning messages are displayed on the screen, and RATE and ERROR values are set to -999.0.
1. Carry out the deadtime correction for the light curve file 'g2.curve' based on deadtime values in the mkfilter file 'ft941123_0821_2301.mkf'.
ft> ldeadtime g2.curve ft941123_0821_2301.mkf