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The Ginga Databases

Data received from Ginga are stored in First Reduction Files (FRFs) which mirror the telemetry stream from the satellite. The format of these files was complex and the software used to read them at Leicester was specific to the VMS operating system. As time moved on this reduced the accessibility of the data for non-expert astronomers. Therefore, the entire dataset was made available via the WWW2 and the software ported to the Unix operating system. The user interface to the raw data was made possible by the creation of a GINGAFRF database table which is a conversion of the Ginga ``kiroku'' or log sheets. However, this Ginga software is not intended for general use as it still requires expertise to fully exploit the data. In recognition of this, a pipeline processing of the raw data was performed to provide quality-controlled reduced Ginga data which would be assessible to non-experts.

Two database tables have been made, GINGALAC and GINGABGD, which contain the pointed observations of target and (nominally empty) background fields respectively. These databases not only provide a summary of the results of each observation, but they also provide access to the data products. These include the FITS spectra and lightcurves, HDS and FITS data cubes and the plots produced during the pipeline processing (see table 1). These products can be used either with the Ginga data analysis software or the XANADU suite of software3. A parallel activity was the creation of background models for the duration of the satellite. These models are crucial to the analysis of the Ginga data as the LAC has no direct means of simultaneously monitoring the background count rate. A number of measured and calculated rates were used to derive the spectral background variations with time due to particle interactions with material in the satellite and its subsequent radioactive decay (see section 2.4 and Hayashida et al. 1989).


next up previous contents
Next: PIPELINE PROCESSING Up: INTRODUCTION Previous: The Ginga Mission
Lorella Angelini
1999-05-29