Ginga was the third Japanese X-ray astronomy satellite. It was launched into low Earth orbit on 5th February 1987 and re-entered the atmosphere on 1st November 1991. The scientific payload consisted of the Large Area Counter (LAC; Turner et al. 1989), the All-Sky Monitor (ASM; Tsunemi et al. 1989) and the Gamma-ray Burst Detector (GBD; Murakami et al. 1989). A full description of the satellite is given in Makino et al. (1987). During its lifetime Ginga performed over 1000 pointed observations of approximately 350 different targets, covering all then known classes of cosmic X-ray sources.
The LAC experiment, sensitive to X-rays with energy 1.5-37 keV, was the main scientific instrument aboard Ginga. It was designed and built under a Japan-UK collaboration (ISAS, U. Tokyo, Nagoya U., U. Leicester, Rutherford Appleton Lab). It consisted of an array of eight collimated co-aligned proportional counters with a total effective area of approximately 4000 cm^2. Steel collimators restricted the field of view to 1.1 x 2.0 degrees (FWHM).
Data received from Ginga were stored in First Reduction Files (FRFs) which mirror the telemetry stream from the satellite. Each FRF file corresponds to a period of time when the satellite was in contact with the ground. Some of the data were telemetered in real time and other data were telemetered from the bubble memory on board. Each FRF file can contain data up to 3 different pointing positions. The raw FITS Ginga data are the FRF files restored in FITS format from their native format (ADP grant, PI Corbet, at Penn State). The FITS files were processed from Penn State on a HEASARC machine and the files directly transferred to the Ginga FTP area at HEASARC. The FITS files are bintable with 5 extensions containing raw counts (science data), raw orbital data, raw operational status data, raw housekeeping data and good time intervals. The layout of the science data extension consists of several columns containing counts, stored as an array per row, and one containing time. The datamode sets the number of channels for the count arrays, how the signal from each counter is summed (number of columns) and the integration time.
This database table was derived using keywords stored in the primary header of the FITS file. Each record corresponds to a different pointing position; therefore, it is possible that up to 3 records may be associated with the same FITS file but have different object names and positions.
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