CROSSCOR (Jan96) xanadu.xronos CROSSCOR (Jan96)
NAME
crosscor -- Calculates cross correlation using a fast or slow
algorithm for 2 input time series
USAGE
crosscor file(s)+options window dtnb nbint nintfm plot plotdev
outfile
DESCRIPTION
This task calculates the cross correlation of 2 input time series,
plots and outputs the results (in a FITS file). The cross
correlation is computed either by an FFT algorithm or a direct slow
algorithm. The paramater "fast" can be used to select the type of
algorithm (the default is set to fast). The input file format is
FITS using the BINTABLE extension. Both binned data format and
event format are input. It requires two simultaneous input time
series (See FILELIST and INPUT FILE OPTIONS). Time, Phase,
Intensity and Exposure windows (See WINDOW) allow for data
screening. Input data can be rebinned and divided into Intervals
and Frames (See GENERAL XRONOS TERMINOLOGY). The results of the
cross correlation from several intervals can be averaged in a
frame. The standard plot output is cross correlation versus time
delay (see PLOT). The time delays refer to the 1st series:
therefore a cross correlation function peaking for positive time
delays indicates that variations in the 2nd series lag those in the
1st series. The cross correlation error bars are from the standard
deviation of the average of the cross correlations in each delay
bin from different intervals, if the specified number of intervals
per frame is larger than the value of "errorbars" parameter
(default =5); otherwise error bars are set =0. For the "slow"
method only, error bars are also obtained by propagating the
theoretical error bars of the cross correlations from individual
intervals (in turn obtained by propagating the newbin errors bars
through the cross correlation formula). Different normalizations
can be used for the auto correlation by changing the parameter
"normalization" (See normalization).
normalization
The "normalization" paramater has the following meanings (and
values) :
* =0 cross correlations are normalised by dividing by the square root of the
product of the number of good newbins of the two series in each
interval, i.e. they are cross covariances.
* =1 (d/f); cross correlations are normalised as in the case =0 and by
dividing also by the square root of the product of the newbin variances
of the two series in each interval.
* =2 cross correlations are normalized as in the case =0 and by dividing
also by the square root of the product of the newbin excess variances
of the two series in each interval. Problems arise when, due to statistical
fluctuations, the excess variance of an interval is negative for any
of the two series. To avoid negative normalization, `crosscor` adopts
automatically normalization 1.
* =3 cross correlations are normalized by dividing by the square root of the
product of the average newbin excess variances of the two series in each
frame after averaging the cross covariances. If the excess variance
in a frame is negative, for any of the two series, 'crosscor'
adopts automatically normalization 1.
If other values than those listed above are used, they are treated
as =0.
GENERAL XRONOS TERMINOLOGY
Within XRONOS tasks, BINS and NEWBINS control the binning used in
the analysis, INTERVALS the subdivision of the time series and
FRAME the grouping of the output results:
BINS : these are the time bins of the time series being analysed.
More than one input file can have different bin durations, e.g. two
consecutive time series, one with 0.5 s bins and the other with 2 s
bins. The original bin time is the value stored in the input file
in the keyword TIMEDEL. If the data are stored in each row as an
array with 1CTYPn = 'TIME', the original bin is set to the value
stored in the keyword 1CDLTn (where n is the column number).
NEWBINS : these correspond to the time resolution at which the
analysis is carried out. Note that: (i) newbins cannot be shorter
than the longest bin duration of the time series being analysed;
(ii) in many XRONOS applications (e.g. powspec, autocor, crosscorr)
the newbin duration is forced to be an integer multiple of the
longest bin duration.
INTERVAL : an interval is defined by the number of newbins over
which the analysis is carried out. Note that in applications using
FFT algorithms (e.g. powspec, autocor and crosscor set in fast
mode) the number of newbins in an interval is a power of 2.
FRAME : a frame consists of the average of the results of the
analysis of one or more contiguous intervals. Note that in
'lcurve', 'efsearch' and 'lcstats' a frame consists always of one
interval.
WINDOWS
If any window is required during the analysis, a window file
containing the relevant windows must be created with the
application XRONWIN, before running a XRONOS task. There are 4
different types of windows :
* Time Windows : consist of up to 1000 time intervals
* Phase Windows : consist of an Epoch, a Period and up to 10 phase intervals
* Intensity Windows : consist of up to 10 intensity in bin, newbin and interval
* Exposure Windows : consist of up to 1 exposure in bin, newbin and interval
Intensity and Exposure Windows can be specified independently for:
(i) Bins , (ii) New Bins , (iii) Intervals. When dealing with more
than one time series, Intensity and Exposure Windows must be
specified separately for each series. Time and Phase windows are
applied to Bins. Intensity and Exposure windows are applied first
to Bins, then Newbins and finally to Intervals as specified. For
time and phase windows, only those bins whose center time is within
the start and stop of a time window or phase window (for a
specified epoch and period) are accepted. Intensity windows must be
ordered with increasing intensity and if set for newbins can be
used in conjunction with "Special Newbin Windows" (see below).
Exposure Windows consist of a minimum and a maximum exposure level.
Units are such that 1 means 100% exposure. The Newbin Exposure is
obtained by propagating the bin exposures to each newbin. For
example, if in a 30 s newbin the total exposure (due to the sum of
the individual exposure of the bins contributing to the given
newbin) is 18 s then its exposure is 60%. The Interval Exposure is
the ratio of accepted to expected newbins: for example, if a 128
newbin long interval contains only 32 accepted newbins, then its
exposure is 25%. Many XRONOS application use some default exposure
windows, which are designed to avoid analysing data sets which are
too inhomogeneous with respect to their statistical properties. The
minimum default Exposure windows in an Interval is set to 0.0 in
the lcurve, efold and efsearch and to 0.5 (i.e. 50% exposure ) in
all the other tasks. Note that exposures can be higher than 100%
(e.g. if the newbin time is not a multiple of the bin time, then
"beats" are generated which might bring the exposure of a newbin to
values >100%; or if two or more input files for the same time
series overlap in part, some of the newbins will be more than 100%
exposed). IMPORTANT NOTE WHEN TIME WINDOWS ARE SET IN THE WINDOW
FILE: The time used within XRONOS tasks is Truncated Julian Days
(TJD= JD-2440000.5) if either (1) the keyword MJDREF is present in
the header or (2) if the TIMESYS value is one of the following
strings MJD or JD or TJD. If (2), the time values are expected to
be stored as JD, MJD or TJD in the header keywords and in the TIME
column in which case the MJDREF keyword is not used (it should not
be present). When Time windows are set using XRONWIN, they must be
compatible with the values in header of the timing keywords and/or
the values in the TIME column.
An additional window type called "Special Newbin Window" can be set
directly from the parameter file. Special Newbin Windows are used
to exclude the parts of a light curve which immediately follow or
precede a burst or a background event which has been rejected by
intensity windows in newbins. The Special Window operates on
newbins in conjunction with intensity windows (in newbins) and are
specified by changing to positive values the parameters
'spwinbefore' and 'spwindowafter'. Their use is the following: if
e.g. spwinbefore is set =10, all newbins, whose center time is
within 10 second before the center time of a newbin rejected by
intensity windows, will also be rejected; if e.g. spwindowafter is
set =20, all newbins, whose center time is within 20 second after
the center time of a newbin rejected by intensity windows, will
also be rejected.
FILELIST and INPUT FILE OPTIONS
To input multiple files for each time series, a file containing the
list of files is needed (Filelist). The Filelist is input in the
program as '@Filelist'. The format of this file list is ascii and
contains one filename+options per line. Files from different times
series are separated by '///' mark. Below is an example of the
Filelist containing 2 files for 3 different times series.
file1_ser1
file2_ser1
///
file1_ser2
file2_ser2
///
file1_ser3
file2_ser3
The Input File Options (up to 10) can be specified for each file in
the same input string. They consist of 2 characters followed by a
numerical constant (up to 8 character long). There are two groups
of options. The first allows data selection within a FITS
extension. The available options within this group are :
frN= start reading input file from row number N (first row)
lrN= stop reading input file from row number N (last row)
vxN= use column number N as x-axis (i.e. time axis, default name is TIME)
vyN= use column number N as y-axis (default names are COUNT or RATE)
vsN= use column number N as error for y-axis (default name is ERROR)
veN= use column number N as exposure (default name FRACEXP).
If the input file is an event list, exposure is by default
calculated using the GTI extension. In this case, N=0
turns off the usage of the GTI extension for the exposure
calculation, and N > 0 specifies the GTI extension to use.
feN= select data (either binned or events) from channel number N (First Energy).
For an event list channel selection is made using the column named 'PHA'
leN= select data (either binned or events) to channel number N (Last Energy).
For event list the default column channel name searched is 'PHA'.
The option 'vcN' allows the choice of a channel column name different from 'PHA' (es. 'PI').
vcN= use column number N for channel selection (valid only for event lists).
rtN= use extension N of the FITS file to read the data. The first extension
is N=1 (the primary array is irrelevant). To specify the extension the
following also can be used: filename[N] or filename+N.
of = The MJDREF keyword is not used. The time is calculated using the
TIME column and the TIMEZERO keyword.
The second group of options performs algebraic operations on
individual input files. They are applied in the same order in
which are specified. For event files they are applied after the
data are binned. The available options within this group are:
stX = Shift all Time in input file by X days
ssX = Shift all times in input file by X Seconds
muX= multiply data and errors by X (MUltiply)
mdX= multiply data by X (Multiply Data)
meX= multiply errors by X (Multiply Errors
maX= as muX but exposure is divided by X
diX= divide data and errors by X (DIvide)
ddX= divide data by X (Divide Data)
deX= divide errors by X (Divide Errors)
daX= as diX but exposure is multiplied by X
aaX= add data and errors with X (Add All)
adX= add data with X (Add Data)
aeX= add errors with X (Add Errors)
saX= subtract data and errors with X (Subtract All)
sdX= subtract data with X (Subtract Data)
seX= subtract errors with X (Subtract Errors)
qaX= add to data the square of data muliplied by X and add to errors
the product of data and error multiplied by X
qdX= as above but for data only
qeX= as above but for error only
Below is an example of the Filelist containing 2 files for 3
different times series where the different options are applied to
the input files for different time series.
file1_ser1 aa4 add to data and error 4
file2_ser1 aa4 " " " "
///
file1_ser2 rt2 aa2 read 2nd extension; add to data and error 2
file2_ser2 rt2 aa2 " " " " " " "
///
file1_ser3 rt2 vy4 vs5 read 2nd extension; use column 4 and 5 for Y-axis and Error
file2_ser3 rt2 vy4 vs5 " " " " " " " " " "
PLOT
The array of results from each XRONOS task can be plotted. The PLT
routine (See also QDP/PLT manual) provides the interactive plotting
and fitting functions. The plotting function is available for the
following tasks : autocor, crosscor, efold, efsearch, lcurve,
powspec and timeskew. The 'crossocor' plot is the cross correlation
function versus time delay (positive and negative) given in seconds.
A number of commands can be entered from the 'PLT>' prompt to allow
plot customisation (e.g. Add/remove labels; Plot data with various
combinations of lines, markers, and error bars; Change text fonts;
Change X-axis and/or Y-axis; Change number of plotted panels;
Define and Fit models to data). Useful QDP Commands are:
PLT> r x xlow xhigh * Rescale X axis
PLT> r y ylow yhigh * Rescale Y axis
PLT> r xlow xhigh ylow yhigh * Rescale both
PLT> log x * X axis is plot in logarithmic scale
PLT> log y * Y axis is plot in logarithmic scale
PLT> log off * Turn off the logarithmic axes (both X and Y)
PLT> dev /xxx * Change the current plot device
PLT> mo ? * List available model
PLT> mo cons linr * Define model= constant plus linear
plt> fit * Fit the defined model
PLT> hardcopy filename * Hardcopy of the current plot (postscript)
PLT> exit * EXit: to exit from the PLT subroutine type:
The QDP/PLT software is provided and maintained by Allyn Tennant
(Marshall Space Flight Center). The PLT software uses the PGPLOT
Graphics Subroutine Library for plotting, written by T.J. Pearson
(California Institute of Technology).
OUTPUT
The analysis results are output in a FITS file. Two different FITS
layouts are available (see parameter outfiletype). The first stores
one interval (or frame) of interval results per FITS table row, and
the output file will have a single extension. The second stores one
interval (or frame) per FITS extension, and the output file will
have as many extensions as the number of intervals (or frames).
The output file contains, besides the array of results, a number of
statistical variables (and errors if appropriate) associated with
each interval (or frame) for each time series. These are: 1-
average count/s in frame (in a frame this is the average of the
averages in intervals); 2- fractional exposure in frame (from
average of fractional exposures in intervals, the latter is the
ratio of good newbins to the total number of expected
newbins/interval); 3-variance in frame (average of variances in
intervals); 4- expected variance in frame (average of the expected
variances in intervals, the latter is calculated from the error
bars of the newbins); 5- 3rd moment in frame (average of 3rd
moments in intervals); 6- minimum count/s in frame; 7- maximun
count/s in frame; 8- excess variance in frame (average of excess
variances in intervals, the latter is calculated as
variance-expected variance); 9- chi-square in frame (average of
chi-squares in intervals); 10-rms fractional variation in frame
(average of rms fractional variation in intervals, the latter is
calculated as the square root of the excess variance divided by the
average.
When "outfiletype"=2, the output file for the 'crosscor' task
contains in each extension the following columns: time delay, half
width of time delay bin, cross correlation and error. Not many
applications can currently deal with the output files produced when
"outfiletype"=1. The format will be described in future releases.
PARAMETERS
cfile1 (filename(s) first series+options) [string]
Input filename(s) for the first time series + options. The
valid input files are in FITS format using the BINTABLE
extension. Xronos tasks read for each time series many
consecutive input files (up to 50). Additional flexibility is
provided by Input File Options which are used to perform
algebraic operations on individual input files (either on the
'times' or on the 'count' or 'count/s' values). The Input file
Options are also used to select columns and rows within a FITS
file. If the first character of the input string is '@', the
rest of the string is taken to be a filename containing the
list of input files (Filelist). The Filelist can contain
filenames for more than one series. See description of
"FILELIST and INPUT FILE OPTIONS".
cfile2 (filename(s) second series) [string]
As PARAMETER cfile1 (See description of "Filelist format and
Input File Options").
window (name of window file) [string]
Filename of the xronos window file. The window file is an ASCII
file and by default a standard window file is used, where only
exposure windows are set. To modify the standard file or
create a new file used the script XRONWIN.
dtnb (integration time) [double]
The duration in seconds of the NEWBIN time. For binned input
files the NEWBIN duration can not be shorter than the longest
bin duration in the input file. In a number of XRONOS tasks the
NEWBIN time must be an integer multiple of the minimum newbin
time. The task internally calculates (and prints on the
screen) a default value such that a single interval is produced
with a fixed number of newbins (typically between 128 and 4096
depending on the task and on the time interval length see also
"nbdf" parameter). Typing 'INDEF' forces the task to use as
NEWBIN time the value calculated by the program. NOTE: By
pressing return the task will use as NEWBIN time the value
found in the parameter file used in a previous run.
nbint (number of points per interval) [integer]
The number of newbins per interval used in the analysis. The
"nbint" together with the NEWBIN duration determines the length
in time of an interval and therefore the total number of
intervals within the start and stop time over which the
analysis will be carried out. Typing 'INDEF' forces the task
to use the default value (see parameter "nbdf"). NOTE: By
pressing return "nbint" is set to the value found in the
parameter file used in a previous run.
nintfm (number of intervals per frame) [integer]
The results of the analysis from individual intervals can be
averaged to produce a frame. The "nintfm" is used to specify
the number of intervals averaged in a frame. Typing 'INDEF'
forces the task to use the default value (all intervals will be
use in one frame). NOTE: By pressing return "nintfm" is set to
the value found in the parameter file used in a previous run.
itre (Flag for trend removal) [integer]
A polynomial trend, up to 4th-order, can be removed from input
time series. Setting the parameter "itre" equal to 1 or 2 or 3
or 4 remove a 1st, 2nd, 3rd, 4th-order polynomial trend,
respectively. The trend is determined separately for each
interval of each series by using a least-square technique. The
value 0 does not cause the removal of any trend from the input
series and is the default value. NOTE The trend removal is not
available for the efold and efsearch tasks.
itremo (Mode for trend removal) [integer]
Specify how the trend removal is applied to the data (available
only id "itre" is higher than 0). The trend can be subtracted
from the time series (itremo =1) , or the time series can be
divided by the trend (itremo = 2), or the time series can be
replaced with the trend (itremo = 3). By default the trend is
subtracted (value set to 1).
outfile (output filename) [string]
Name of the output file. If only the root is given, the program
adds an extension of 3 characters, '.fXX', where f stands for
FITS and XX is a suffix which identifies the program that
creates the output. The XX values are : 'ac' (autocor), 'cc'
(crosscor), 'ef (efold), 'es' (efsearch), 'lc' (lcurve), 'ps'
(powspec), 'ts' (timeskew). Typing '-' forces the program to
generate a default value for the output filename (see
outfileroot parameter). By typing blank characters at the
prompt no output file will be created.
outfileroot (default value) [string]
This parameter used in conjunction with "outfile" generates a
default output filename. If the value of "outfileroot" is
'default' and "outfile" is '-', the output filename will have
the same root name of the first input file of the fits series
with a '.fXX' extension (see outfile for XX values).
outfiletype (Type of FITS layout) [integer]
Define the FITS structure for the output file. Two types are
available. The first type (outfiletype=1) has 1 interval of
results per FITS table row. The output file will have only one
extension. Each row of the results column contains an array of
values with a size equal to the number of points per interval
(or frame) and a number of rows equal to the valid number of
intervals analysed. The second type (outfiletype=2) has 1
interval of results per FITS extension. The output file will
have as many extension as the number of intervals (or frames)
analysed. The column containing the results has a single
element value in each row and the number of rows is equal to
the number of points in the interval. The default value of
"outfiletype" is 2 (one interval per FITS extension).
plot (if plot) [boolean]
Flag specifying whether or not the results of the analysis are
plotted via PLT (default = yes). NOTE: After plotting the
results the XRONOS task is left in the interactive
plotting/fitting mode (PLT> prompt) use command `exit` to
return and finish the XRONOS task. If the "plot" parameter is
set = no, the other queries regarding the plotting are disabled
("plotdev", "plotfile", "plotdum").
plotdev (device) [string]
Change the plot device. The most common plot devices are /xw (X
window), /tek (tektronix), /vt (vt125), /ps (PostScript).
Setting "plotdev" as '?', forces the program before plotting to
list the available plot devices to the terminal and to prompt
for this parameter again.
plotfile (.pco file) [string]
Name of the Plt COmmands file. For each task an appropriate
default Plt COmmand file is automatically loaded by the program
setting the parameter "plotfile" as '-'. The user can insert
additional commands using his own '.pco' file at this level (
or within the PLT> prompt).The user commands are appended to the
default command file and therefore executed last. The default
'.pco' files are stored in the directory defined by the
parameter 'dpath'.
tchat (terminal chattiness) [integer]
Set terminal chattiness: (0-4) only little information is
output in running XRONOS task ; chattiness 5 is the default
value; (6-7) more details on input files, windows, intervals
statistics, etc.; (<8) mostly for debugging purposes.
lchat (log file chattiness) [integer]
Set log file and chattiness in the log file: = 0 the log file
is not written; for all other values, information is written in
the log file. The chattiness levels are the same as for the
terminal.
logname (log filename) [string]
Name for the log file. The default name is xronos.log.
clobber [boolean]
Flag specifying whether or not a pre-existing file with the
same name as that requested for an output file in the current
task will be overwritten. Default value = yes.
(dpath = XRDEFAULTS) [string]
This string parameter gives the path to the Xronos 'defaults'
directory, which contains the default '.pco' file (used for
plotting) and the defaults window file 'default_win.wi'.
Ordinarily, the user may leave this parameter set to the string
'XRDEFAULTS', which causes Xronos to use the environment
variable XRDEFAULTS to locate these files. XRDEFAULTS is set by
the mkftools script to point to the appropriate directory for
the current distribution of Xronos (for FTOOLS v3.6 this is
/ftools/xronos/defaults/). If the user wishes to modify these
files, he or she may make and edit copies, and change the
XRDEFAULTS variable appropriately using setenv, but the
original files should not be changed.
gapfill (running mean gap filling) [integer]
Replace gaps in input series with running mean. If =0 (the
default) data gaps are not filled. If =n newbin data gaps in
input series are filled in with running mean values calculated
over n newbins. Note that a gap newbin is filled in only if the
corresponding running mean is calculated over n/4 points at
least (this means that in order to bridge a gap of m newbins n
must be >1.35m). This global parameter is ignored in epoch
folding applications (efold and efsearch).
forcestart (flag for start time) [boolean]
If = yes the first interval will be forced to start at the time
of the first time window otherwise (=no default) the center
time of the first qualified newbin is used as the start time.
errorbars (Error bar Evaluation) [integer]
This parameter defines the way in which the error bars of the
analysis results are calculated. If the number of the intervals
per frame ("nintfm") is higher than "errorbars" value
(default=5), the error bars are evaluated by using the standard
deviation of the average (based on the measured scatter).
Otherwise the error bars are evaluated by propagating the
theoretical error bars through an averaging process. Note that
for several XRONOS applications (e.g. `autocor`, `crosscor`)
only the former way of evaluating error bars is available. For
example, if "errorbars" is 5 in the application `powspec`: (a)
if a frame contains the average of 5 or fewer power spectra,
then the error bars in the average power spectrum will be
calculated by propagating through the average the theoretical
error bars associated with each power spectrum (in turn
obtained from the relevant chi-square distribution); (b) if a
frame contains the average of 6 or more power spectra, then the
error bars in the average power spectrum will be calculated by
evaluating the standard deviation of the average power for each
frequency. By adjusting the value of "errorbars" it is
possible, e.g. to evaluate error bars as in (a), also in the
case in which a large number of intervals per frame has been
specified. Values < 5 are not recommended (at least 5-6
measures are necessary to reliably evaluate the standard
deviation of the average from the scatter around it). NOTE: not
applicable for 'lcurve', 'lcstats' and 'efsearch'.
exposure (flag for analysis of exposure profile) [boolean]
If =yes the exposure profile(s) (i.e. newbin values are set =1,
gaps and rejected newbins are set =0) is/are analysed (instead
of the input series). Default value is = no.
normalization (type of normalization) [integer]
Flag to specify the type of normalization to apply to the
results. This parameter is only relevant for the following
tasks: powspec, autocor, efold, crosscor, timeskew). The
standard normalization corresponds to a value of 1 (the
default) in all XRONOS applications. Other normalization value
flags are described for each application (See normalization).
NOTE: not applicable for 'lcurve' and 'efsearch'.
simultaneous (flag for simultaneity) [boolean]
If =yes a strict simultaneity is forced between the input
series in applications which use more then one series (i.e. if
the n-th newbin of a series is a gap or is rejected, then the
n-th newbin of all other series will be also rejected). This
flag is ignored in the efold applications. Default value is =
no.
spwinbefore (special window start) [double]
Special newbin window : number of seconds before. If a value >
0 is used , e.g. 10.0, then all the newbins within 10.0 seconds
before a newbin rejected by an intensity window will also be
rejected. The default (=0) is not to apply this type of special
newbin window.
spwinafter (special window stop) [double]
Special newbin window : number of seconds after. If a value >0
is used , e.g. 10.0, then all the newbins within 10.0 seconds
after a newbin rejected by an intensity window will also be
rejected. The default (=0) is not to apply this type of special
newbin window.
rescale (rescaling for results) [double]
Rescaling factor applied to result variables and errors. The
rescaling is applied just before writing the output file (this
to avoid affecting the statistical variables for the frame).
Default value for "rescale" is set to 1.
offset (additive constant for results) [double]
Additive constant summed to result variables. Result error bars
are left unchanged. The additive constant is added just before
writing the output file (this is to avoid affecting the
statistical variables for the frame). Note that if a rescaling
factor is also specified (different from 1), then the results
are first multiplied by the rescaling factor. Default value for
"rescale" is set to 0.
fast (Flag for fast algorithm) [boolean]
This parameter sets the type of algorithm used for the Fourier
transform. IMPORTANT NOTE: This parameter can be set by the
user only in the `powspec`, `autocor` and `crosscor` tasks (it
is a query parameter in these tasks). In all the other tasks
"fast" is a non-query parameter, and should not be changed from
the default setting.
nser (Number of time series) [integer]
Number of input time series simultaneously processed.
IMPORTANT NOTE: This parameter, the values of which range
between 1 and 4, can be set by the user only in the "lcurve"
and "efold" tasks (it is a query parameter in these two cases).
In the other tasks "nser" is a non query parameter, and should
not be changed from the default setting.
ipow2 (Flag if power of 2) [integer]
Internal Flag used to decide if the current task must used with
a power of 2 of number of points (ipow2=1) per interval or not
(ipow2=0). IMPORTANT NOTE: This parameter should not be changed
by the user.
iavgreb (Flag if average interval) [integer]
Internal Flag used to decide if the current task allows the
averaging of intervals in frame and/or the rebinning of the
analysis results. If "iavgreb" is set to -1 the results in an
interval can not be either averaged or rebinned, if set to -2,
the results in an interval can be averaged but not rebinned.
IMPORTANT NOTE: This parameter should not be changed by the
user.
nbdf (Default No. Bins) [integer]
Set an internal default value for the number of newbins per
Interval. This value is used to calculate the default newbin
integration time to have one interval with nbdf points.
Different "ndbf" values have been set for different XRONOS
task. IMPORTANT NOTE: With caution this parameter can be
changed by the user.
EXAMPLES
1. Given 2 time series with an original binning of 1 second and
length 1.5 hours compute the cross correlation in intervals of
1024 points and average all the results per interval in a frame.
Make a plot and output the results.
> crosscor cfile1="mydata1.lc" cfile2="myfile2.lc" window="-" dtnb=1 nbint=1024
nintfm=INDEF plot=yes plotdev="/xw" outfile="-"
2. As before but using as input file a list of filenames (@all.lis)
(see "Filelist and Input File Options").
> crosscor cfile1="@all.lis" window="-" dtnb=1 nbint=1024 nintfm=INDEF plot=yes
plotdev="/xw" outfile="-"
3. Given 2 time series with an original binning of 1 second and
length 1.5 hours compute cross correlation using all the data in
one interval (nintfm=1). The number of points in such interval
length are 5400 and for the fast method this requires that the
number of points be a power of two. The closest value is 8192.
> crosscor cfile1="@all.lis" window="-" dtnb=1 nbint=8192 nintfm=INDEF plot=yes
plotdev="/xw" outfile="-"
SEE ALSO
efold, efsearch, autocor, powspec, lcstats, lcurve, listdata,
timeskew xronwin, fits2qdp, ascii2lc.
BUGS
Report problems to angelini@lheavx.gsfc.nasa.gov and
xanprob@athena.gsfc.nasa.gov. Provide a detailed description of
the problem (with a log file if possible).
Please send reports of errors to : xanprob@athena.gsfc.nasa.gov HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public Last modified: Thursday, 06-May-2004 13:46:55 EDT HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details. |
HEASARC Staff Scientist Position - Applications are now being accepted for a Staff Scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the High Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.
