burst - Remove bursts of events from time ordered event list
       cktime - Checks that a time column is time ordered
     day2time - Convert time offset (in days) relative to a reference date/time
                to an absolute date/time
     deadtime - Update the exposure of PHA file by deadtime based on GTIs
       fltime - Filter an event list within given time intervals (GTIs)
   makefilter - Create a filter file from Housekeeping files.
     maketime - Calculate time intervals (GTIs) from housekeeping (HK) data
       mgtime - Merge 2 or more time interval (GTI) files 
     sec2time - Convert time offset to absolute time
     time2day - Calculate time (days) between input and reference date/time
     time2sec - Convert absolute time to a time offset