gsh7w@astsun.astro.Virginia.EDU (Greg Hennessy) (12/06/90)
The situation on ASTRO continues to improve, but is by no means as good as possible. BBXRT is observing, and getting almost all of its data, although there was a temporary glitch of the Two Axis Pointing System (TAPS). HUT works well, but has still not aquired any targets. It has observed 10 objects that WUPPE aquired when WUPPE was primary, or by manuan acquisition, and gotten VERY nice data. WUPPE has observed 10 objects, and has one exciting result already, even before the instrumental polarization is fully finished. There is a well known dip in UV spectra around 2300 angstroms, which is attributed to graphite, probably in dust grains. The question is wheter or not the light is scattered off the grains, or absorbed by the grains. This all was pointed out 25 years ago by Ted Stecher, the PI of the UIT telescope. If the light was being absorbed, the polarization would not be changed, but if the light was scattered, there would be a large polarization induced into the starlight. The WUPPE team found that the polarization did NOT change across the line, meaning that the light is being absorbed not scattered. The UIT telescope made five long exposures, and 3 short ones. There long observations included the Perseus cluster, NGC2992, and the Crab Nebula, and M87. The science teams are still not happy with with the tracking. When the star trackers acquire the stars, the stability is very nice, but the trackers often do not work. Another patch was uplinked last night and another test will be this shift. On shift four there was 0 percent of science being done, on shift five there was 17, and on shift six there was 35 percent. However that 35 percent counted the time lost for a test as the star trackers as zero time achieving science, but took in the time. If you only consider the times that the teams attempted to observe, then the teams achieved 44 percent. The mission is being replanned to take longer exposures, so better data of fewer objects will be done. -- -Greg Hennessy, University of Virginia USPS Mail: Astronomy Department, Charlottesville, VA 22903-2475 USA Internet: gsh7w@virginia.edu UUCP: ...!uunet!virginia!gsh7w