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During the XRCF calibration, ACIS science data were monitored by an operator on the second floor of the facility using the ACIS Quick Look Computer (AQLC), a computer workstation developed by the ACIS team. The AQLC obtains AXAF telemetry generated by the CTUE in real time, via the ACIS EGSE. The AQLC consists of two subsystems. The ACIS Telemetry Interpreter for Calibration Analysis (ATICA), converts the AXAF telemetry stream into a sequence of FITS files containing the ACIS science data. The telemetry processing performed by ATICA is essentially the same as that described in Section 5.1.
The second subsystem, Tools for ACIS Real-time Analysis (TARA), provides the human operator with a suite of tools for analyzing in real time the science data contained in the FITS files produced by ATICA as well as full-frame CCD data obtained directly from the ACIS hardware by the EGSE's `High Speed Tap'. (As the HST data does not pass through the telemetry it is not available during the flight.) TARA includes a variety of tools - some written specifically for TARA and some incorporated from other data analysis packages - for visualizing, reducing, and analyzing ACIS data. Some examples of these tools include:
TARA is a collection of computer programs which scientists use to analyze ACIS calibration data. Some of these are standard tools which have been in use for years in the astronomy community; others were written by the ACIS team specifically to analyze ACIS data. In the same way, some of the programs are stand-alone, and others are functions which have been integrated into a convenient GUI (Graphical User Interface) for use in an interactive mode during Analyst activity at XRCF or data reduction in a home site. The GUI interface form is known as Event Browser. Important stand-alone programs are CCD_viewer and fits_viewer, which allow direct display of raw CCD images and FITS files made by the ACIS software.
External packages which are heavily used in ACIS processing include the commercial IDL (Interactive Data Language), supported by RSI; the XANADU package (including FTOOLS, XSPEC and XRONOS), supported by Goddard Space Flight Center; and SAOimage, supported by the Center for Astrophysics. The ACIS team does not supply support or documentation for these packages, and refers users to the appropriate institution.
TARA is available for public distribution through the Penn State Web site at:
Table 5.1 lists the IDL tools written by the ACIS team. Documentation for each of these tools is available by using the xdl command from within IDL.
John Nousek