The Project survived a few technical problems discovered after the last Newsletter. Fortunately, as has been the case with this extremely robust observatory, the impact to performance has been minimal. We have also overcome problems caused by proton damage to the front-illuminated (FI) CCDs: Guided by improved understanding and extensive monitoring of the radiation environment, operating procedures have kept additional degradation of the FI CCDs to acceptable levels. Furthermore, users now customarily use S3, the central back-illuminated (BI) CCD in the spectroscopic array, for spectrometric imaging. Work on recovering some of the lost energy resolution of the FI CCDs proceeds; however, the final verdict is not in yet.
We have learned to deal with a timing error in the HRC electronics (which impacted my own Cycle 1 GO observations of the Crab Nebula and Pulsar!): Users can now fully exploit the time resolution of the HRC for faint sources by telemetering all events; for the brighter, telemetry-saturating sources, users can still achieve millisecond time resolution by filtering on the time between events. A mechanical problem with the microswitches that sense whether the HETG is inserted or retracted has been resolved, and has no direct impact on scientific performance.
Discoveries continue at a rapid pace. The Cycle 3 proposal deadline approaches and we are in the early throes of planning the symposium ``Two Years of Chandra!" It doesn't get much better than this.
Martin C. Weisskopf