Search for periodicity using the timesorted output file.
This task determines the period which produces the folded light curve with maximum deviation (i.e. chi sq) from that of a constant source. It outputs the folded light curve as a function of phase in rp90_sec2_fld.tab, and the run of chisquare vs. period in rp90_sect2_chi.tab.
The sample interval must be set short enough so the sampling is complete. To search for a period pseconds in an observation of length t seconds, sorting into n bins, the period interval, , should be . If the user specifies a period increment of ``0'', the computer will calculate this interval.
The parameter get_gintvs=yes requires that an exposure be calculated for each interval, important if the period is comparable to the duration of gaps and good-data intervals.
input file: rp90_sect2_sti.qp
output files: rp90_sect2_fld.tab, rp90_sect2_chi.tab
xt> period.pdot=4.22e-13 # enter value of period derivitive (units, s s-1) # if known. Default is 0.Note: For those sources with a period which changes linearly with time, enter dp/dt value (4.22e-13 is the value for the Crab pulsar).
xt> period Input Source Timing File: rp90_sect2 # assumes extension _sti.qp Input Background Timing File: none Root name for output files [root_fld.tab, root_chi.tab]: rp90_sect2 # Assigns name rp90_sect2_fld.tab Period start: 90 # units are seconds Period stop: 110 Increment (0 for auto increment): 0.1 Number of bins: 10 # trial periods will be divided into 10 phase bins.Results may be viewed using
xt> chiplot rp90_sect2_chi # command line mode