Period Folding

Period Folding Functions

1. sitar_pfold_rate( t, rate, p [ ; pdot=#, pddot=#, nphs=#, tzero=#] )
   Fold a rate lightcurve on a given period (with optional first and second derivatives).
   Run as: isis> profile = sitar_pfold_rate(t,rate,p; pdot=#,pddot=#,nphs=#,tzero=#);
   Variables in [] are optional qualifier variables.
   Omitted qualifier variables take on default values.
   
   Inputs:
   • t : Times at which rates are measured
   • rate : Lightcurve rate
   • p : Period on which to fold the lightcurve
   Optional Qualifier Inputs:
   • pdot : Period derivative. Default=0.
   • pddot : Period second derivative. Default=0.
   • nphs : Number of phase bins in output folded lightcurve. Default = 20
   • tzero : Time of zero phase. Default = t[0]
   Outputs:
   • profile.bin_lo : Start value of phase bin
   • profile.bin_hi : Stop value of phase bin
   • profile.mean : Mean rate in phase bin
   • profile.var : Variance of rate in phase bin
   • profile.sdm : Standard deviation of the mean rate in a phase bin
   • profile.num : Number of data points in phase bin
   
   
2. sitar_pfold_event( t, p, gti_lo, gti_hi [ ; pdot=#, pddot=#, nphs=#, tzero=#] )
   Fold a rate lightcurve on a given period (with optional first and second derivatives).
   Run as: isis> profile = sitar_pfold_rate(t,rate,p; pdot=#,pddot=#,nphs=#,tzero=#);
   Variables in [] are optional qualifier variables.
   Omitted qualifier variables take on default values.
   
   Inputs:
   • t : Times at which rates are measured
   • p : Period on which to fold the lightcurve
   • gti_lo : Array of lower boundaries of good time intervals
   • gti_hi : Array of lower boundaries of good time intervals
   Optional Qualifier Inputs:
   • pdot : Period derivative. Default=0.
   • pddot : Period second derivative. Default=0.
   • nphs : Number of phase bins in output folded lightcurve. Default = 20
   • tzero : Time of zero phase. Default = t[0]
   Outputs:
   • profile.bin_lo : Start value of phase bin
   • profile.bin_hi : Stop value of phase bin
   • profile.cts : Counts in phase bin
   • profile.var : Variance of rate in phase bin
   • profile.expos : Integrated exposure in phase bin