The idf_cut program allows you to cut an IDF file into several smaller IDF files into which the records of the input IDF files are sorted according to their time-phase.
Usage: idf_cut [-hm] [-v level] idf_file RefTime Period Nout Arguments: RefTime : Reference Time in seconds since EXPSTART Period : Period in seconds Nout : Number of output files. Options: -m: interprets RefTime as MJD -h: this help message -v: verbosity level (=1; 0 is silent)
The name of the Nout output IDF files are
{input_IDF_filename}.p{X}.fit where X=0..Nout-1
An event from the input file gets sorted into output file X if it happened at time t such that there exists an integer k that satisfies :
where T is the period.
The m switch is used to specify that RefTime is a Geocentric Modified Julian Day instead of a number of seconds since start of exposure.
If you just want to cut your files in time bins without folding on a period, use start of exposure for the reference time, end of exposure minus start of exposure for the period and choose the number of bins you want with the last parameter.
If you are running this program on a combined IDF files, note that some of the output files may be empty, because of the gaps between the exposures.
If you care about the bad pixels correction, you need to run cf_bad_pixels on each of the output files. Again this means that at this point you should not have combined the exposures.