7.1 Routine Science Data Processing

Science data obtained with HST are sent to the TDRSS satellite system, from there to the TDRSS ground station at White Sands, New Mexico, then to the Sensor Data Processing Facility at Goddard Space Flight Center in Greenbelt, Maryland, and then finally to STScI. At STScI the production pipeline provides standard processing for data editing, calibration and product generation. These functions, performed automatically, include the following:

• Reformatting and editing of data from spacecraft packet format to images and spectra.
• Performing standard calibrations (flat fields, wavelength calibrations, background subtraction, etc.) with currently available calibration files.
• Producing standard data output products (FITS files of raw and calibrated images, OMS [jitter and performance flags] files, and so on).

The standard calibrations performed on HST data, and the resulting output data products, are described in detail in the HST Data Handbook. Note that, as of the summer of 2000, STScI no longer archives calibrated data; the production pipeline is run on-the-fly, as described in Section 7.2.1.)

7.1.1 Space Telescope Science Data Analysis System (STSDAS)

STScI maintains a set of tools and support software used to calibrate and analyze HST data. The main component of this is the Space Telescope Science Data Analysis System (STSDAS), which is accompanied by TABLES, a set of tools for creating and manipulating tabular data, reading and writing FITS images and tables, and creating customized graphics. STSDAS and TABLES are layered onto the Image Reduction and Analysis Facility (IRAF) software from the National Optical Astronomy Observatories (NOAO). You must be running IRAF in order to run STSDAS and TABLES. STSDAS and TABLES are supported on a variety of platforms, although not all of the platforms that IRAF supports. STSDAS contains, among many other things, the same calibration software that is used by the HST data pipeline. HST observers can therefore recalibrate their data, examine intermediate calibration steps, and re-run the pipeline using different calibration switch settings and reference data. Detailed information on STSDAS and TABLES, including the actual software, is available from the STSDAS Web page. Information about IRAF is available from the IRAF Web page.