ltcurv

ltcurv

xray.xtiming

ltcurv

NAME · USAGE · DESCRIPTION · PARAMETERS · EXAMPLES

NAME

ltcurv - Bin photons and compute the count rates of timing data.

USAGE

ltcurv source_file background_file ltcurv_file bins bin_length

DESCRIPTION

LTCURV bins source and background photons into specified time intervals and computes a count rate for each bin.

The good time intervals for the data are read from the source QPOE file, and are used in computing the time exposure of each bin. The precursor task to this is TIMSORT which selects and sorts a QPOE file in time order. TIMPRINT will display the output and LTCPLOT will plot output table data. Corrections are not yet being applied for Fractional Spatial Exposure.

PARAMETERS

source_file = prompt = Input Source Timing File: Required input in time ordered QPOE format. The file is created by running TIMSORT on a specified source region. The file may be specified by supplying the rootname and a "_sti.qp" extension will be appended by the task before looking for the file. For example input "i6757" is interpreted as "i6757_sti.qp".

background_f = "NONE" prompt = Input Background Timing File: Optional input in time ordered QPOE format. The file is created by running TIMSORT on a specified background region. The file may be specified by supplying the rootname and a "_bti.qp" extension will be appended by the task before looking for the file. For example input "i6757" becomes "i6757_bti.qp". Enter "none" to skip this parameter.

ltcurv_file = prompt = root name for output file

				[root_ltc.tab]

Required Output filename. The file is written in table format. The file may be specified by supplying the rootname and a "_ltc.tab" extension will be appended. For example input "i6757" becomes "i6757_ltc.tab". Each row in the table represents 1 bin of folded data. The column titles and definitions are as follows:


	time ----------- start of the bin in space-craft time units
	ctrt ----------- count rate
	err ------------ count rate error
        exp ------------ exposure
	src ------------ source counts
        bkgd ----------- background counts
	net ------------ net counts (src - bkgd)
	neterr --------- net error

A table file header is also written. It consists of parameters copied from the input QPOE file and parameters recorded from running this task.

bins = prompt = Number of Bins (for bin length): The number of data bins. Input 0 if specification of bin length is preferred.

bin_length = prompt = Bin Length in Secs: The length of a bin in seconds. If bins is 0, specification of bin_length is required.

(display = 1) [int]: The display level. A few of the parameters and computed time intervals are displayed to the user for those who like to see that things are happening. Input 0 for no output and 5 for the maximum level.

(clobber = no) [boolean]: Boolean flag specifying whether or not the table file can be overwritten if it already exists.

(get_gintvs = yes) [boolean]: Boolean flag specifying whether to filter the input events through the good time intervals stored in the QPOE file. It is useful to turn this parameter off when analyzing lab data where good intervals are not applicable or in a file without the intervals.

(bk_norm_fact = 1.) [real]: Background Normalization factor. This is an extra fudge factor that can be used to adjust the ratio of source to background area.

EXAMPLES

Type `help timfilter` and `help timsort` for information concerning
input files.

1. Make a light curve from the time sorted source QPOE file snr_sti.qp. No background is used and the number of bins is 100. The data is written to snr_ltc.tab.


	xt> ltcurv
	Input Source Timing File: snr_sti.qp
	Input Background Timing File (NONE): 
	Output Table File: snr
	Number of Bins: 100

	Creating ltcurv file: snr_ltc.tab

2. Make a light curve from the time sorted source QPOE file snr_sti.qp and background file snr_bti.qp. In this example the number of bins is skipped by specifying 0, and the length of each bin is 0.5 seconds. The data is written to my_ltc.tab.


	xt> ltcurv
	Input Source Timing File: snr
	Input Background Timing File (NONE): snr
	root name for output file [root_ltc.tab]: my_ltc.tab
	Number of Bins (0 for bin length): 0
	Bin Length: 0.5
	
	Creating ltcurv file: my_ltc.tab

3. Make a light curve from the time sorted source QPOE file snr_sti.qp with a time filter for the third good time interval. In this example the number of bins is skipped by specifying 0, and the length of each bin is 0.5 seconds. The data is written to snr3_ltc.tab.


	xt> ltcurv
	Input Source Timing File: snr_sti.qp[time=(79492486.63:79494689.51)]
	Input Background Timing File (NONE): 
	root name for output file [root_ltc.tab]: snr3
	Number of Bins (0 for bin length): 0
	Bin Length: 0.5

	Creating ltcurv file: snr3_ltc.tab

4. As in example 3 above only in command line format.

	
	xt> ltcurv "snr_sti.qp[time=(79492486.63:79494689.51)]" "none" 
	"snr3" 0 0.5 clobber+
	
	Creating ltcurv file: snr3_ltc.tab

.ih
TIME REQUIREMENTS
.ih
BUGS 
No Corrections are being applied for Fractional Spatial Exposure.
.ih
SEE ALSO
Documentation on errors (\fIhelp explain_errors\fR) 
for a description of the error calculations implemented in PROS.

Documentation on region filtering (\fIhelp regions\fR) for a
description of the spatial filter user interface.

Documentation on QPOE filtering (\fIhelp qpoe\fR) for a description of
the QPOE filter user interface.
 
Documentation on file extensions (\fIhelp extensions\fR) for a
description of PROS file extensions.

Documentation on coordinates (\fIhelp coords\fR) for a description of
PROS coordinate conventions.
.endhelp




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This file last updated on 16 Nov 1995