5.1 Introductory Remark

For purposes of planning HRI observations (and of analyzing data as well), the performance of the combined HRI and ROSAT XRT (X-ray telescope) is described in this report, which is based upon laboratory, ground-based, and in-flight data.

The HRI information in this document supersedes that in previously issued versions of the ROSAT Mission Description (e.g., APPENDIX F of the U.S. announcement [ROSAT AO-21991, NRA 91-OSSA-31991]; references below to ``Appendix F'' refer to the version dated ``January 1991''). It has been reorganized to some extent in order to improve the clarity of presentation. To assist those familiar with Appendix F, the following concordance is provided for finding updated material corresponding to sections of that appendix:

This document Appendix F section

5.1 Introductory Remark 4.3.1

5.2 Performance 4.3.2

5.2.1 Detector Geometry 4.3.2.1

5.2.2 Spatial Response 4.3.2.4

5.2.3 Effective Area 4.3.2.2, 11.1

5.2.4 Background 4.3.2.6, 7.8.3

5.2.5 Spectral Response none (i.e., new)

5.2.6 UV Response 4.3.2.3

5.2.7 Event Timing 4.3.2.5

5.3 Feasibility of observations 11.

5.3.1 General Assumptions 11.1

5.3.2 Point Source Sensitivity 11.2, 11.5

5.3.3 Expected Count Rates 11.3

5.3.3 Examples 11.3.1

5.3.4 Time Variability Studies 11.6

5.3.5 Comparison to the Einstein HRI 11.7

	This document	Appendix F section
5.1	Introductory Remark	4.3.1
5.2	Performance	4.3.2
5.2.1	Detector Geometry	4.3.2.1
5.2.2	Spatial Response	4.3.2.4
5.2.3	Effective Area	4.3.2.2, 11.1
5.2.4	Background	4.3.2.6, 7.8.3
5.2.5	Spectral Response	none (i.e., new)
5.2.6	UV Response	4.3.2.3
5.2.7	Event Timing	4.3.2.5
5.3	Feasibility of observations	11.
5.3.1	General Assumptions	11.1
5.3.2	Point Source Sensitivity	11.2, 11.5
5.3.3	Expected Count Rates	11.3
5.3.3	Examples	11.3.1
5.3.4	Time Variability Studies	11.6
5.3.5	Comparison to the Einstein HRI	11.7