When running epoch folding applications (e.g ef1, ef2, efs) several additional questions are asked. The first is to specify the format in which the epoch of zero phase will be entered:
ef1> Format for epoch
{1=d / 2=d s / 3=d h m s ms} [1]=>
The default (1) is to enter the epoch in days. The other possibilities are (2)
to enter the epoch in (integer) days and seconds and (3) to enter the epoch in
days, hours, minutes, seconds and milliseconds. After that, the epoch should be
entered in the specified format:
ef1> Epoch [ 302.00000000]=>By replying to the following question:
ef1> Format for period {1=d / 2=s} [2]=>
it is possible to specify whether the period over which the input data are to
be folded should be entered (1) in days (the default) or (2) in seconds. After
that the period should be entered according to the specified format (note that
in application efs the period entered represents the centre of the range of
trial periods over which the data will be folded):
ef1> Period [ 0.00000000E+00]=>The following question is issued in order to enter the number of phasebins in the folded light curve(s):
ef1> No. of Phasebins/Period (max: 65536)
{value or neg. power of 2} [ 128]=>
The duration of a phase bin represents in the context of epoch folding
applications the equivalent of the newbin duration. The default is such as to
produce a folded light curve of 128 bins at most.
Application efs requires two additional inputs. The first is the period resolution to be used in the search; this is entered by replying to the following question (note that the same units used to enter the period should be used):
efs> Period Resolut. [ 0.18018900E-05]=>The default is half the Fourier resolution over the interval (i.e. P*P/T(i)/2, where P is the trial period and T(i) the interval duration). If the default resolution is used a coherent periodicity will appear as a 1-2 bin broad peak in the chi-square vs. trial period plot.
The second is the number of periods over which the search should be carried out:
efs> No. of Periods (max: 7281)
{value or neg. power of 2} [ 128]=>
The number of periods should be kept as small as possible in order to limit the
execution time.