Issue |
Astron. Astrophys. Suppl. Ser.
Volume 136, Number 2, April II 1999
|
|
---|---|---|
Page(s) | 407 - 418 | |
DOI | https://doi.org/10.1051/aas:1999431 | |
Published online | 15 April 1999 |
BeppoSAX Low-Energy Concentrator Spectrometer background subtraction techniques
1
Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
2
Pembroke College, University of Oxford, St Aldates, Oxford, OX1 1DW, UK
3
Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching bei München, Germany
4
BeppoSAX Science Data Center, Nuova Telespazio, via Corcolle 19, I-00131 Roma, Italy
5
Department of Physics and Astronomy, Southampton University, SO17 1BJ, UK
Send offprint request to: A.N. Parmar
Received:
17
November
1998
Accepted:
2
February
1999
We present 3 methods for the subtraction of non-cosmic and
unresolved cosmic backgrounds observed by
the Low-Energy Concentrator Spectrometer (LECS) on-board BeppoSAX.
Removal of these backgrounds allows a more accurate modeling of the
spectral data from point and small-scale extended sources.
At high (>
) galactic latitudes, subtraction
using a standard background spectrum works well.
At low galactic latitudes, or in complex regions of the X-ray sky,
two alternative methods are presented. The first uses counts obtained from
two semi-annuli near the outside of the LECS field of view
to estimate the background at the source location. The second method uses
ROSAT Position Sensitive Proportional Counter
(PSPC) all-sky survey data
to estimate the LECS background spectrum for a given pointing position.
A comparison of the results from these methods provides an estimate
of the systematic uncertainties.
For high galactic latitude fields, all 3 methods give 3σ confidence
uncertainties of <
count s-1 (0.1-10 keV),
or <
count s-1 (0.1-2 keV).
These correspond to 0.1-2.0 keV fluxes of
0.7-1.8 and
erg cm-2 s-1
for a power-law spectrum with a photon index of 2
and photoelectric absorption of
and
atom cm-2, respectively.
At low galactic latitudes, or in complex regions of the X-ray sky,
the uncertainties are a factor ~2.5 higher.
Key words: instrumentation: detectors / methods: data analysis / diffuse radiation / X-rays: general
© European Southern Observatory (ESO), 1999