pcecor HEADAS help file

NAME

pcecor -- Corrects PI channel in Events file

USAGE

pcecor infile outfile alkfile calflag

DESCRIPTION

This tool operates on Rev0, or RDF PSPC events file. The tool also operates on any German PSPC events file converted to RDF format using the 'gevt2rdf' ftool.

pcecor uses calibration data from the PANTER facility in Neuried to correct for the variation in the linearity of the PSPC response with absolute gain. The data were collected several years after the launch of ROSAT using the engineering model PSPC. It was observed that the effective gain in the 0.25 - 1.0 keV energy range was lower than expected after normalizing to the 1.5 keV monitor line, and this effect became worse with lower absolute gain. For example, a 0.75 keV X-ray might be detected as a 0.72 keV X-ray when the PSPC was operating at low gain. Data from higher energy calibration lines were collected at the same time, which allowed a check of response linearity over an extended energy range. Note that this correction was never implemented in SASS.

NOTE: A bug in the PCECOR ftool has resulted in too small a correction being applied to the PI channel. This bug has now been fixed and the alternative correction algorithm, based on Prieto et al. (1996, A&A Suppl., 120, 187), has also been incorporated into the tool.

In the new version, users can choose from one of two options for the PI correction: 1) Using calibration data from the PANTER 2) Using in-flight observations of calibration sources (such as N132D) to determine the PI correction as a function of time. See Prieto, Hasinger and Snowden (1996) for details.

THE CALIBRATION FILES REQUIRED FOR THE TASK

The default setting for the input calibration files is 'CALDB', this facility can only be used by beta-test sites of the calibration database access software. Most users will need to obtain a set of calibration files via anonymous ftp from heasarc.gsfc.nasa.gov. The datasets are located in the directory:

         ftp://heasarc.gsfc.nasa.gov/caldb/data/rosat/pspc/bcf/alk_gainmaps

SUPPORTED FITS FILE FORMATS

   Currently only the following OGIP standards are supported by this task

For the input events file :
RDF EXTNAME = 'STDEVT'
US REV0 EXTNAME='EVENTS'
HDUCLAS1='EVENTS'
HDUCLAS2='ACCEPTED'

For the Calibration files :

For further details see OGIP calibration memo CAL/ROS/95-010

PARAMETERS

infile [character string]: The name of the Events file.
(gtifile) [character string]: The name of the GTI file. Defaults to the name of the Events file (infile).
outfile [character string]: The name of the output file.
alkfile [character string]: The names of the alk gainmaps.
calflag [integer]: Flag to indicate which callibration to use. For calflag=1, ground callibration file is used and for calflag other than 1, in-flight callibration file used.
(chatter=9) [Integer]: Flag to indicate how chatty the task is at execution. A value of 9 is the default, with lower/higher values producing quieter/verbose output respectively.
(clobber = no) [boolean]: Overwrite output file, if it already exists ?

EXAMPLE

Note that this example assumes that the user has CALDB access properly configured. The easiest way to do this is to access the CALDB at the HEASARC over the internet - see http://heasarc.gsfc.nasa.gov/docs/heasarc/caldb/caldb_remote_access.html




% pcecor
Please enter EVENTS filename[] rp900176n00_bas.fits
Please enter alk history file[caldb]
Please enter output filename[] pcecor_bas_out.fits
Which correction algorithm to be used [grnd=1/inflight=2]?:[] 2
 ** pcecor 1.2.4
 ** pcecor 1.2.4 completed successfully

BUGS

None known

LOG OF SIGNIFICANT CHANGES

v1.0.0 (1996 Feb)

v1.2.0 (1997 Oct)

included option to use either ground or in-flight callibration data.

Report problems using the FTOOLS help desk:

http://heasarc.gsfc.nasa.gov/cgi-bin/ftoolshelp