Contents: 1) FUSE Mission Status 2) Second FUSE Observers Advisory Committee meeting, on November 15 3) NRA for Cycle 2 of FUSE GI Program 1) FUSE Mission Status After four months in orbit FUSE has started initial science observations as In-Orbit Checkout (IOC) activities near completion. Regular science observations for PI Team and GI programs will begin in December 1999. We are happy to report that initial observations of two white dwarf calibration standards indicate that FUSE's sensitivity in orbit is excellent. The effective area of all four channels is consistent with the pre-launch predictions. The detector background level is low, at, or slightly below, the pre-launch estimate. The grating scattered light level is extremely low. This coupled with the low detector background means that zero (or non-detectable) flux corresponds to zero counts. The spacecraft pointing stability is better than the mission requirement. Even though the telescopes and spectrograph have not yet been focused, the spectra already have a resolution of about 20 km/sec, which is within 60% of what we eventually expect to achieve. Observations of scientific targets began in late September. Both galactic and extragalactic sources have been observed, primarily for Early Release Observation (ERO) programs and some from PI Team programs. A number of interesting scientific results have already emerged and will be reported in a FUSE poster session at the AAS meeting in January 2000. More detailed discussions of the early FUSE results, including instrument performance, will be submitted for publication in a special issue of Astrophysical Journal Letters, which we hope will appear shortly before the FUSE Cycle 2 observing proposal deadline (i.e., spring of 2000). IOC and Science Verification (SV) activities have taken significantly longer than the two months planned prior to launch. The main reasons for the delays are: 1) the spectrograph outgassing was slower than anticipated, which delayed detector high voltage turn-on by about 4 weeks; 2) target acquisitions were hampered by a bug in Fine Error Sensor flight software and by larger than expected roll errors following target acquisition; 3) memory fragmentation in the Instrument Data System compromised efficient instrument operations; 4) intermittent problems with the primary FUSE ground station in Puerto Rico significantly reduced overall operational efficiency; 5) Single Event Upsets (SEUs) in detector RAM, correlated with passage through the South Atlantic Anomaly, result in memory errors and occasionally in detector shut-downs and subsequent lengthy recoveries. These problems have either been solved (1-4) or an operational solution will be implemented in the very near future (5). The ability to coalign the four telescopes to within 2 arcsec has been demonstrated. Until very recently the SiC channels were generally misaligned with respect to the LiF channels. The coalignment appears to be affected by thermal effects, including changes in solar orientation, especially at high beta angles. Engineering tests are underway and we expect to finish characterizing the alignment stability by the end of November. To date all observations for science programs have had to use the LWRS aperture (30x30 arcsec). A cyclic motion of the spectra during each orbit has been detected and is being characterized. This spectral drift in the dispersion direction is about 5-15 detector pixels (10-30 km/sec peak-to-peak). The spectral shifts are larger in the LiF channels than in the SiC channels. Initial studies indicate that this effect may be thermal in origin and that it can be modeled and removed from time-tag data as part of the calibration pipeline processing. In order to expedite delivery of FUSE science data to FUSE observers and the archive while instrument characterization and calibration continues, the FUSE data processing pipeline has been modified to omit several calibration steps. These steps will be implemented at a later date once accurate corrections have been determined. Observers should be aware that at this time the calibrated data will not include background subtraction (which is probably negligible in many cases), flat-field correction, astigmatism correction, nor will there be any correction for the spectral drifts mentioned above. The FUSE Project felt it was better to apply no correction than to apply one that is inappropriate for flight data. The pipeline processing will evolve with time as more is learned about instrument performance, and the users will be kept informed about any significant developments via this Newsletter. FUSE data is currently being processed, as described above, and will be delivered to the Multi-Mission Archive at the Space Telescope Science Institute (MAST) over the next few weeks. Access to proprietary FUSE data will be established through a MAST password protected account for the program PI, and any designees of the PI, in the same manner as is currently done for HST programs. Non-proprietary FUSE data can be accessed by anyone, after registering for an account with MAST. Both raw data and extracted spectra are stored in the archive. In summary, we have encountered several bumps in the road that have slowed the commissioning process, but we are very excited by the early scientific results from FUSE and look forward to the next several months when more and more of you will be able to share in what promises to be a wealth of new scientific discoveries from FUSE. George Sonneborn FUSE Project Scientist Warren Moos FUSE Principal Investigator Those of you interested in the progress of IOC and "Science Verification" (SV) process, may follow it through weekly summaries of the status reports posted at: 2) Second FUSE Observers Advisory Committee meeting, on November 15 The FUSE Observer's Advisory Committee (FOAC) will have its second meeting at JHU on November 15th. The membership of the FOAC and the minutes from its first meeting can be found at: The minutes from the second FOAC meeting will also be posted at the above site as soon as they are ready. 3) NRA for Cycle 2 of FUSE GI Program We would like to give you a "heads-up" about the call for proposals for cycle 2 of the FUSE GI program. The NASA Resarch Announcement (NRA) for FUSE Cycle 2 GI proposals is presently planned for release in February 2000. Proposals will be due approximately 90 days after the NRA release, with the exact date being specified in the NRA. ------------------------------------------------------------------------------- The Observer's Electronic Newsletter is published by the FUSE project and is aimed at the FUSE user community. Editor: B-G Andersson, FUSE Guest Investigator Officer. The FUSE Project is managed by Johns Hopkins University's Center for Astrophysical Sciences in Baltimore, MD, for NASA's Goddard Space Flight Center. The FUSE Principal Investigator is Dr. Warren Moos, the FUSE Project Manager at JHU is Mr. Dennis McCarthy, and the NASA Project Scientist for FUSE is Dr. George Sonneborn. Further information about the FUSE Guest Investigator Program can be obtained from: Dr. George Sonneborn; sonneborn@stars.gsfc.nasa.gov ------------------------------------------------------------------------------