Folding a time series

The program foldcb folds a section of a Ginga data cube or time series on a given period. The output file contains the folded light curve and has the root name of the input file with the extension ".fld". If the satellite position is important then the times should be corrected to a common frame of reference. The program foldcb_hjd calculates the time delay to the heliocentric frame of reference before folding the data. The programs are useful for producing phase resolved spectra from an input Ginga data cube (see section 7 for details about spectral fitting). An example of foldcb is given below (the interface to the program foldcb_hjd is identical):

qcl>foldcb

** FOLDCB Version 1.3 Mon Aug 11 18:53:46 1997 **
 
FLD_CUBE Data file name =mkn335_91a.sub_corr
 Base MJD               48439.231250000
 Number of time samples             393
 Sample duration          128.000000000
 Number of PHA samples               48
 Number of IDENTs                     2
 
FLD_TLO  Start time in data slice = 0.0 =
FLD_THI  End time in data slice = 50304.0 =
FLD_EPOCH  Epoch = 48439.231250000 =
FLD_PERIOD  Fold period (secs) = 0.0 =1000.0
FLD_BINS  Number of phase bins = 8 =7
FLD_IPLO  Min PHA channel for fold histogram = 1 =4
FLD_IPHI  Max PHA channel for fold histogram = 48 =30
FLD_IDENT  IDENT channel for fold histogram = 1 =1
 Phase samples   128.000000000 seconds
 
 FOLDCB Complete
qcl>

Program foldts folds a section of a Ginga time series on a period or range of periods: the period may also change linearly with time. In the case of multiple folds, the output file contains the (against the constant source hypothesis) of the folded light curve at each period, as well as the actual folded light curve at the period having the maximum . In the other case, that of a single fold, the output file contains only the folded light curve (i.e. the result is the same as with program foldcb). The output file has the root name of the input file with the extension type ".fld". The results may be displayed using the qcl procedure pl_fold.qcl (see section 8.3 ). The following is an example of its use:

qcl> foldts
** FOLDTS Version 1.4 Tue Aug 19 15:08:14 1997 **
 
FLD_CUBE Data file name =mkn335_91a.sub_corr
  
 FOLDTS: Multiple folding of time series 
  
 Program limitations: 
  Maximum number of trial periods: 1000
  Maximum number of phase bins per fold: 300
  
  Base MJD                       48439.231250000
  Number of time samples                     393
  Sample duration                  128.000000000
  Number of pulse height samples              48
  Number of IDENTs                             2
 
FLD_TLO Start time in data slice = 0.0 =
FLD_THI End time in data slice = 50304.0 =
FLD_IPHA PHA channel for fold = 1 =4
FLD_IDENT Ident channel for fold = 1 =
FLD_DO MEAN, MINMAX or SCATTER = MEAN =
FLD_EPOCH Fold epoch = 48439.231250000 =
FLD_START Start period (seconds) = 0.0 =10000.0
FLD_END End period (seconds) = 0.0 =20000.0 
FLD_DELTA Period increment (seconds) = 0.0 =1000.0
FLD_PDOT Rate of change of period = 0.0 =
FLD_BINS Number of phase bins = 78 =10
 
  Phase samples                  1000.000000000 seconds
  Number of folds to be done                 11
 
Fold:    1 Period:   10000.0
Fold:    2 Period:   11000.0
Fold:    3 Period:   12000.0
Fold:    4 Period:   13000.0
Fold:    5 Period:   14000.0
Fold:    6 Period:   15000.0
Fold:    7 Period:   16000.0
Fold:    8 Period:   17000.0
Fold:    9 Period:   18000.0
Fold:   10 Period:   19000.0
Fold:   11 Period:   20000.0
 
 Statisitics of fold with maximum chisquared
 
  Period                        18000.000000000
  Minimum level                         -0.2186
  Maximum level                      10000.0000
  Mean level                             0.0418
  Scatter                                0.1977
  Chi-squared                           17.5701
  Number of degrees of freedom                9
 Output file: mkn335_91a.fld
        
FOLDTS Complete
qcl>

Finally, the program fold_multi folds up to 50 time series (simultaneous or not) on a single period. The output file contains only the folded light curve. In addition, fold_multi may or may not take into account the time delay to the heliocentric frame of reference (this is generated by the program helio). The output file has the same root name as the first input file, but takes the extension ".fld". The results may be displayed using the qcl procedure pl_fold.qcl (see section 8.3 ). A feature of the program helio is that one time series channel can be tested to ensure that no spikes are present in the resultant time series. The program helio prompts the user for the spectral channel and detector ident of the light curve to be tested, and the lower and upper limit of accepted data (time bins outside this range are ignored). Examples of helio and fold_multi are shown below:

qcl> helio
** HELIO Version 1.2 Tue Aug 19 15:20:04 1997 **
 
HEL_DATIN Data file name =mkn335_91a.time
HEL_IPHA  Pulse height channel of the time series = 1 =1
HEL_IDENT  Ident channel of the time series = 1 =1
  
 Mean data value = 0.00073938
 Minimum data value = -0.5224772
 Maximum data value = 1.078847
  
HEL_CRMIN Low edge to window = -0.522477 =
HEL_CRMAX High edge to window = 1.07885 =
qcl>

qcl> fold_multi
** FOLD_MULTI Version 1.2 Tue Aug 19 15:20:20 1997 **
 
FLD_NCUBE Number of data files = 0 =1
FLD_CUBE001 Data filenames =mkn335_91a.time
FLD_IPHA001 Pulse height channel for file = 1 =
FLD_IDENT001 Ident channel for file = 1 =
FLD_EPOCH Epoch for folding = 48439.231250000 =
FLD_PERIOD Period on which to fold = 0.0 =10000.0
FLD_BINS Phase bins in fold = 78 =10
 Phase samples  1000.000000000 seconds
FLD_TCORR Use time corrections? = Yes =
 
 FOLD_MULTI Complete
qcl>