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The Leicester Ginga Databases
D. A. Smith & J. P. Osborne
Department of Physics and Astronomy, University of Leicester,
Leicester, LE1 7RH, UK
Abstract:
The Japanese satellite Ginga made over 1000 observations of
celestial X-ray sources with the LAC collimated proportional counter
during 1987-91. Its large area, ~4000 cm², and broad energy
range, 1.5-37 keV, made the Ginga LAC a unique and popular X-ray
detector.
In this paper we describe the automatic processing of the Ginga LAC
MPC1 data to produce the databases. Over 80% of Ginga observations
were made in this mode, which provided full spectral resolution
together with 16 second time resolution. We describe the production of
a series of universal background models which were
used to background subtract both source and off-source (nominally
empty) fields. Some datasets were background-subtracted using a
local method which made use of contemporaneous
background observations where these were available. We describe the
data selection and the various quality checks that have been made. The
results of the processing are available in the
gingalac and gingabgd databases
within the Leicester data archive service. They include count rates,
hardness ratios, a variability measure and the results of limited
spectral fitting. A uniformly applied quality flag is also
provided. There are product files associated with each database
entry. These files conform to the OGIP FITS conventions where
applicable. They include data cubes, spectra and light curves, and
also plots summarising the quality of the observation and the results
of the spectral fits.
The data in the gingalac and
gingabgd databases will allow the less expert user to
benefit from the Ginga observations. These have not previously been
widely available, being in a Ginga-specific format, but are now made
available for the more experienced user in the
gingafrf database at the same location.
[Next: Introduction]
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