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Calibration Planning

AXAF calibration at the XRCF comprises measurements of the following:

  1. alignment
  2. focus
  3. point or line response function
  4. encircled energy
  5. effective area/quantum efficiency
  6. wavelength scale
  7. spatial conversion
  8. count rate linearity
  9. molecular contamination search
  10. fluorescence source search
  11. ghost image search
  12. background
Several of these measurement involve mapping a large parameter space. For example, the effective area needs to be calibrated as a function of energy, off-axis angle, detector position, grating order, etc. An XRCF calibration-test database has been set up by the ASC with inputs from the SAO Mission Support Team, the Science Instrument teams, and MSFC Project Science. This database now contains over 6000 entries. To deal with its size and complexity, and reduce the chance of error, the ASC will use a macro language to populate the database from at most a few hundred human-readable and checked inputs. In addition, the calibration test plan can be updated and revised easily. The ASC is using Sybase to store the calibration planning information. With sophisticated Sybase query tools, a variety of reports can be generated from the database for scientific review, error checking, and further calibration planning.

Figure 2. An aerial view of the X-ray Calibration Facility (XRCF) at the Marshall Space Flight Center (MSFC), Huntsville, Alabama. [Photo courtesy of MSFC]

Figure 3. A sketch of the XRCF layout. The X-ray Source System (XSS) is located in Building 600. One of the two beam normalization detector systems (BND-500) is about 125 feet away from the XSS, and it is located in Building 500; the other (BND-H) is at the HRMA entrance. The BND-H, HRMA, and the focal plane detectors (HXDA and SIs) are all housed in an instrument chamber, which is about 1700 feet from the XSS and in a three story control build. The test control center is on the 2nd floor of the control building, and a data analysis center is on the 3rd floor.

I will next summarize the two important subsystems, XSS and HXDS.



next up previous contents
Next: The X-ray Source Up: AXAF at the Previous: Facility overview


axafnews@asc.harvard.edu
Wed Sep 13 12:40:01 EDT 1995