ASCA Calibration Database
Files and information regarding the ASCA calibrations are kept in the HEASARC Calibration Database . On this page we highlight some calibration files and articles that are most commonly required for ASCA analysis.
The ASCA GIS
- Background files have been created from a superposition of
15 blank sky fields observed during the ASCA PV phase (May 93 - Mar 94). The
files are for various magnetic rigidity values and are having *all* in their
name (each for the two detectors) includes all the events, regardless of the
magnetic cut-off rigidity (COR) values. Since the GIS internal background
increases as COR decreases, other files are sorted by COR values (in units of
GeV/c). There are directories containing
sky+particle background,
night earth (particle) and sky+particle background when the
spread discriminator was turned off during the early mission PV phase (up
to 1993, May 28; 80015000, Hydra A).
In the article Background characteristics of the GIS by Kubo et al. a description of the GIS background is described. This article appeared in Volume 2 of the asca newsletter AscaNews.
It was pointed out that moderately bright point sources in these GIS background files are not completely averaged out and may affect BGD subtraction results. Please refer to Warning about GIS BGD files.
- The
latest Response Matrices are available from the ASCA calibration
database.
The detector response is split up into RMF and ARF files. The RMF describes
the elements of the response that do not dependent on the focal plane
position. There are two RMF files, one for each telescope:
- gis2v4_0.rmf for GIS2
- gis3v4_0.rmf for GIS3
- gis3v4_0_128ch.rmf for GIS3 with 128 PHA channels. This RMF should be used for GIS3 data suffered from the on-board CPU trouble between 1994 February 10 and 1994 April 8.
- The ARF takes into account the telescope response, which
depends on the source location, extent and extraction region. The ftool
ascaarf should be used to generate an ARF for each spectrum accumulated. For
convenience combined ARF+RMF=RSP files are given for the standard
pointing positions.
- gis2v4_0_1ccd.rsp GIS2 at the nominal 1-CCD pointing position
- gis2v4_0_2ccd.rsp GIS2 at the nominal 1-CCD pointing position
- gis2v4_0_4ccd.rsp GIS2 at the nominal 1-CCD pointing position
THESE FILES SHOULD ONLY BE USED FOR SIMULATIONS.
- Other GIS
calibration files are also available from here
The ASCA SIS
-
Background files for both SIS detectors are available
from 3 deep field observations without
any obvious sources and with a total exposure of about 120 ks. The
events were cleaned using the "select mkf" command in XSELECT
(with ELV_MIN > 20 and SAA = 0). Hot and flickering pixels were
removed using the "sisclean" command in XSELECT (sisclean method
2, with cell size 5, log probability -5.24, background level 3).
Any spurious events which remained were removed by manual
cleaning based on the light curve (i.e. excluding spikes and drop-
outs). The background rate is a weak function of the lower limit of
magnetic cut-off rigidity and files have been generated for
different rigidity ranges. These files contain both the particle
and sky backgrounds. The article
Initial Report on the SIS Internal Background
in Volume 2 of the asca newsletter,
AscaNews, describes
the SIS background and a model for the particle background. This is by
Keith Gendrau, who has also written several other interesting calibration
reports.
- The SIS response matrices should be generated with the FTOOL
sisrmg for
each spectral file extracted; this is because the response is dependent
on the time of observation, the detector coordinates of the soruce,
and on the observing mode. The latest calibration files that are
used by sisrmg (including sisph2pi_110397.fits, which is also used
by sispi) are distributed with FTOOLS in the refdata area, but they
can also be found
here.
Some of the old SIS RMF and RSP files (i.e. response matrices which include the
ARF or telescope response) are available for the standard 1-CCD mode position.
They should only be used for quick-look purposes and simulations:
- Other SIS
calibration files are also available from here
This file was last modified on Tuesday, 19-Oct-2021 16:25:14 EDT
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