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Session 29 - High Resolution X-ray Imaging & Spectroscopy with AXAF.
Display session, Tuesday, June 10
South Main Hall,

[29.02] Absolute Calibration of the AXAF Telescope Effective Area

E. Kellogg, D. Schwartz, L. P. VanSpeybroeck, B. Wargelin, I. Evans, W. C. McDermott, S. S. Murray, M. V. Zombeck, T. Gaetz, D. Jerius, R. Edgar, W. Podgorski, L. Cohen, M. Freeman (SAO), M. Weisskopf, S. O'Dell, B. Ramsey, R. Elsner (NASA/MSFC), J. Kolodziejczak (USRA), G. Garmire, J. Nousek (PSU), S. Kraft, F. Scholze, R. Thornagel, G. Ulm (Physikalisch-Technische Bundesanstalt), K. Flanagan, D. Dewey, M. Bautz (MIT), J. Arenberg, R. Carlson (TRW)

The prelaunch calibration of AXAF encompasses many aspects of the telescope. In principle, all that is needed is the complete point response function. This is a function of energy, off-axis angle, and operating mode of the facility. No single measurement would yield the entire result. Prelaunch conditions will change in orbit, such as absence of gravity, and contamination of surfaces. We concentrate here on the total throughput of the observatory, i.e., the integral of the point response function, the encircled energy. Since there is no standard X-ray source in the sky whose flux is well known to the 1% accuracy we are trying to achieve, we must do this calibration on the ground. We monitor prelaunch calibration changes until on-orbit operation can transfer the calibration to a celestial X-ray source. We analyze the elements of the absolute throughput calibration, the Effective Area, and present preliminary results. We analyze calibration error contributions. An absolutely calibrated detector, calibrated at a synchrotron, is essential for prelaunch measurements. The goal is to compare absolute X-ray fluxes of celestial sources with those at other wavelengths.

Program listing for Tuesday