Folds events into multiple periods
pfold infile outfile periodgrid [dtffile] [pdot] [nphase] [tzero] [clobber]
`pfold' folds an event file into a grid of period bins with a fixed number of phase bins. If a good time interval (GTI) is attached to the input file, the first block is used to exposure-correct each bin. Similarly, if a dead time factor (DTF) file is supplied, then a further per-bin DTCOR correction is applied.
pfold acis_evts.fits fold.fits 2:2000:1 nphase=10
Folds the events into 10 phase bins with periods ranging from 2 sec to 2000 secs in steps of 1 sec. The first GTI will be used to correct the count_rate column.
pfold hrc_evts.fits fold.fits 2:2000:1 nphase=10 dtffile=hrc_dtf.fits
An HRC file is folded into 10 phase bins with periods ranging from 2 sec to 2000 secs in steps of 1 sec. The DTF file is used to correct the count_rate column.
Detailed Parameter Descriptions
Parameter=infile (file required filetype=input)
Input event file
The input event file should have a 'TIME' column and be sorted in time (i.e. chronological events). If present, the first GTI block will be used to correct the count_rate column.
Parameter=outfile (file required filetype=output)
The output file has one row per period. There are array-columns for the phase, counts, rate, ontime (exposure), dtf, and a scalar mean_rate and sigma_rate.
Parameter=periodgrid (string required)
Grid of periods to search
This should take the form of min:max:step, where step can be
- a single number (the step size)
- the number of output bins ("#number")
- number"l" for logarithmicly-spaced points
- #number"l" for number of logarithmicly-spaced bins
Parameter=dtffile (file not required filetype=input)
Dead time factor file
The file must have TIME and DTF columns, e.g. an HRC dead time factor (DTF) file. This file may be created by running the dither_region tool.
A Data Model filter is used to specify the TIME and DTF columns in the file. DM syntax allows the user to specify a column with a different name as the DTF information, e.g.
Parameter=pdot (real not required)
Derivative of period
Parameter=nphase (integer not required default=10)
Number of phase bins
Parameter=tzero (real not required)
The zero time for start of phase bin.
Setting tzero=INDEF (the default) uses the time of the 1st GTI record. Users trying to match the phase between observations (or observatories) should set tzero to a specific value.
Parameter=clobber (boolean not required default=no)
Overwrite existing output dataset with same name?
Changes in CIAO 4.15
The period must be positive, so the tool now errors out if the periodgrid evaluates to any values 0 or less. The behavior has been improved for periods significantly smaller than 1.
Fixed crash when the period=0, and improved support for periods much, much less than 1.0 seconds.
The periodgrid can now be specified using the standard CIAO grid syntax. This includes min:max:step, min:max:#steps, and grid(filename).
There are no known bugs for this tool.