Note from the Top
ROSAT continues to operate nearly flawlessly. Over the past several months, virtually no observing time has been lost as a consequence of acquisition failures or spacecraft safe holds. Only two minor annoyances have crept into the routine mission operations. Some constrained observations are performed only with difficulty or low efficiency due to new target acquisition constraints associated with the single gyro operations. The newly-developed HRI hot spots are scrutinized on a daily basis, to ensure they are not worsening. Contrasting strongly with these small difficulties is the fact that no major spacecraft system shows a potential mission-ending problem. ROSAT will stay in orbit until the next solar maximum, and it is possible that it will stay operational until that time.
The current AO6 timeline, released in late March, 1996, contains observations through October 10, 1996. Observations after that time will be selected in the AO7 review. The international solicitation for AO7 observations was released on March 1. Proposals are due on May 15. The national proposal review and the International User's Committee meeting are scheduled for July.
In the U.S. AO7 solicitation, we reiterate the evolution of the U.S. ROSAT program towards so-called "large observing programs." These programs request substantial fractions of the U.S. time. In general (but not always) they take several years to complete. Among the multiyear large programs underway are mappings of the Small and Large Magellanic Clouds, an international program to map the Cygnus Loop (see cover), and a survey of the X-ray source population of Local Group dwarf galaxies.
The large observing programs also provide one of the two major themes for a special half-day ROSAT workshop to be held in San Diego, CA, on Monday, April 29, 1996, immediately before the AAS-HEAD meeting. The purpose of the workshop is to provide a forum for discussion about the future usage of the U.S. share of ROSAT time. The workshop presentations and discussions will be used as one source of material for the ROSAT proposal to this summer's NASA Senior Review of astrophysics missions, the mechanism by which NASA establishes the funding level for operations and Guest Observer support for all its missions. During the workshop, the PI's of the large programs currently underway will present status reports, and individuals with ideas for new programs will have an opportunity to present them for discussion. The second major theme of the workshop will be how ROSAT can continue to pave the way for AXAF. Speakers from the U.S. ROSAT Science Data Center and the AXAF Science Center will present their views of what ROSAT can offer as a "pathfinder" for AXAF, and scientists familiar with both missions will explore various scientific themes in this light. Substantial time will be made available for contributed presentations and for discussion.
We plan on summarizing the workshop presentations in the next ROSAT Newsletter. As the future of the U.S. ROSAT program depends on a favorable outcome of the Senior Review, all are urged to participate in the workshop.
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