You can combine your IDF files from the command line with idf_combine.
Usage: idf_combine [-ahbc] [-v level] output_idf_file input_idf_files Options: -h: this help message -v: verbosity level (=1; 0 is silent) -a: ignore EXP_STAT keyword -c: recalculates Y centroids (use target events) -b: store ORBITAL_VEL in a float
Here is how to combine all exposures of observation M1010101 for segment 2A.
idf_combine -c M1010101all2attagfidf.fit M1010101*2attagfidf.fit
Without the c switch, the Y centroid of the LiF and SiC target apertures wouldn't be re-calculated. The EXP_ID keyword in the main header of the output file is set to '999'. Thus after extraction, you will get the two files:
M10101019992alifttagfcal.fit M10101019992asicttagfcal.fit
The a switch makes the program ignore the EXP_STAT keyword. This means that exposures that have EXP_STAT strictly positive will not be rejected as would be the case without the a switch. The EXP_STAT keyword is set to a strictly postive value by the pipeline if the exposure is bad or for histogram (HIST) files that contain bursts, SAA crossing or low limb angle: these exposures contain many bad events that cannot be screened because HIST files are not time-tagged.
The b switch will be discussed later.