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ROSAT Guest Observer Facility

A Note from the Top

These past few months have seen both good and bad for the ROSAT program. On the positive side, the satellite continues to operate nearly perfectly, after nearly three and a half years of operation. No further degradation of the Attitude Maintenance and Control System has occurred, and in the event that the second star tracker on the X-ray telescope fails, software is ready for using the WFC tracker as a substitute. More importantly, the gas flow rate through the PSPC was reduced in June, with no ill effects. This accomplishment guaranteed that the AO4 observing program ( which runs through December 20, 1993) could be completed, and even left some small margin in the gas supply. By that time, virtually all AO1-4 priority A and B observations will have been completed. By the end of 1993, ROSAT will have carried out nearly 5,000 pointed observations.

Scientific results based on ROSAT data continue to flood the literature. The bibliography of ROSAT papers published in refereed journals has already reached 200, and only a small fraction of the results have reached publication. It is a particular source of pride for the program that the 1993 Bruno Rossi Prize was awarded essentially for a ROSAT result. Other Rossi-prize-quality results are either in the works or waiting to be found. In the past few months, ROSAT has discovered X-rays from a supernova only five days after optical maximum (despite theorists’ predictions to the contrary). Another observation has resolved a major observational mystery by revealing that the 12ks periodicity thought to be arising in the Seyfert galaxy NGC6814 really arises from a nearby, previously unknown, AM Her-type cataclysmic variable star.

While the impending end of the PSPC lifetime might be viewed with some sorrow, the mission will not end. The German Space Agency has committed to several more years of satellite operations. The upcoming era of HRI-only operations provides the astronomical community with an unprecedented opportunity for high resolution X-ray imaging, using the highest quality X-ray mirror ever to be placed into orbit. Sadly, the community enthusiasm for such an opportunity clashes headlong with fiscal reality. Due to the severe constraints imposed upon future MO&DA budgets, the ROSAT program has been cut by 30 percent in fiscal 1994. These cuts were imposed despite the fact that ROSAT had been given the highest reviews by not one, but two, MO&DA advisory panels convened during 1992. A new NASA policy has been implemented since these reviews, whereby a mission is guaranteed MO&DA funding only during its “prime” operations phase. After that time, two years in the case of ROSAT, the mission enters an “extended” operations phase, during which time it may compete for continued funding against other extended missions. NASA plans to offer missions like ROSAT an opportunity to compete for funding as an extended mission in fiscal 1995.

The budget cuts have been absorbed equally by the Guest Observer program and the US Science Data Center. The effect of the former cut will not be felt until the AO5 program, for which there will be substantially less funding available than for previous AO’s. The effect of the latter cut is more immediate: data product verification and validation has been terminated; the PROS development has been slowed; the processing team has been reduced to one shift, without technical support (which results in reduced processing capacity, fewer paper data products, and reduced ability to respond to user queries); and the GO support staff has been cut. The latter is particularly irksome, given the recent discovery of time variations in PSPC performance and the impending heavy HRI usage, and the consequent need to increase rather than decrease the level of effort.

As deeply as the fiscal 1994 cuts have been felt, the long term outlook makes 1994 look like a banner year. Essentially, there is no guarantee that a US ROSAT program will exist as such beyond October 1, 1994. Despite the grim outlook, we are committed to do all we can to keep the US participation in ROSAT—especially the highly successful Guest Observer program— going for as long as possible. For us to be successful, however, depends in a significant way upon the support of the astronomy community. That support can be demonstrated in a number of ways: by publishing ROSAT results in the literature and presenting them at meetings, by using the archive, by submitting ROSAT proposals to the Guest Observer and ADP programs, and by voicing your support to the decision makers at NASA Headquarters.