gsh7w@astsun.astro.Virginia.EDU (Greg Hennessy) (12/06/90)
The observational efficiency of the ASTO observatory continues to increase, but not as quickly as hoped. The star trackers work perfectly whenever tested, but still have not worked on a real object. All science done so far ahas been by the astronauts hand guiding the telescopes, which results in much less stable images than the nominal star trackers. The star trackers can be made to work in a certain fashion, a complicated procedure, but this procedure takes so much time that it often eats up most of the observing time. The last tests on teh star tracker show that the three tubes that compose the star trackers are misaligned by 0.9 degrees. They are supposed to be coplanar. During the eigth shift, two problems occured that lost observing time. One was the crew exercising on the treadmill diring an observation of P Car. The premission understanding was that the crew would only excercise during handovers (times when so science was being done) but this was apparently not written down anywhere. The crew will now only excercise when the shuttle is in an SAA, a region of higher radiation where the instruments do not work. Also during the mission the verniers (small rockets which keep the shuttle pointed in the proper position). Since this meant that the shuttle had to manuver using the large rockets, the shuttle doors were closed to prevent contamination from the fuel, which contains hydrazine. Three observations were missed, unfortunately the high priority targets the Pleiades, VW-Hydra, and the cluster Abell 2199. (Talk about rotten luck). These four targets had zero science done, and specified observation times of 16, 23, 40, and 34 minutes. Sucessful observations were made of the galaxy 0558-504 with 10 of 15 minutes (67%), M79 (14 of 27, 52%), SK69-239 (18 of 33, 55%), M79 again (31 of 45, 69%), NGC 1399 (10 of 26, 38%), P-Cyg (33 of 38, 65%), 3C273 (everybody's favority quasar) 41 of 47, 87%, Capella, 12 of 28, 43%, and HD99264, 20 of 29 minutes for 70 percent. All in total, 39 percent of the scheduled time was done, compared with 36% for shift 7, 17% for shift 6, and 0% before that. The next shifts observations will be done with a software patch to correct for the misalighed star tracker. -- -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w