Compton Observatory Science Report #161, Friday July 8, 1994 Chris Shrader, Compton Observatory Science Support Center Questions or comments can be sent to the Compton SSC. Phone: 301/286-8434 e-mail: NSI_DECnet: GROSSC::SHRADER Internet: shrader@grossc.gsfc.nasa.gov Spacecraft Status The Observatory, scientific instruments and all spacecraft subsystems continue to function nearly flawlessly. Science Support Center Activities Remember all those CGRO Cycle-4 Proposals you painstakingly wrote, duplicated umpteen times, stuffed into Express-Mail envelopes and sent off to us minutes (or less?) prior to the deadline? Well, we haven't forgotten them either - in fact the proposals were all evaluated and ranked on the basis of scientific merit by panels of anonymous referees last week. These rankings, along with the generation of the cycle-4 viewing plan which will be done next week are the two elements which will determine which programs are finally approved for cycle 4. Final results should be mailed out to each proposer later this month. The observatory was heavily oversubscribed and a broad consensus was that the quality of the science proposed was, in most cases, quite excellent. Instrument Reports EGRET EGRET operations were normal during this biweekly period. Delivery of data to the GRO SSC is on schedule. Interaction with guest investigators remains at a good level. The data reduction schedule is slowly recovering from the time lost due to severe thunderstorms and the resulting damage to the EGRET computers. The current viewing period is involves the second portion of the PSR 1951+32 observation. Analysis is well along on the deep survey obtained earlier in phase 3; results should be presented at the AAS meeting and will be of considerable importance to the study of AGN. The results on the high-energy gamma rays seen from bursts, including the spectrum, the highest energy gamma rays observed, and the long time period of detection of the photons, continue to reverberate through the through the community, toppling many theories. It seems now that any theory must include the acceleration or release of very high energy particles that interact for over an hour. The spectrum must also be a power law and not thermal. Combining these findings with those of BATSE severely restricts the possibilities open to theoretical explanations. OSSE OSSE operations are normal. In viewing period 333 (5-12 July), the Z-axis target is Cyg X-3 (PI team), and the X-axis targets were PSR 0611+22 (Guest Investigator J. Cordes) and 4U 0115+63 after its recent outburst. The Sun is available on the scan plane, so the slewing response is enabled. For the last 24 hours of vp 333, we will use two detectors to monitor the spectral state of Cyg X-1. Data from viewing periods 212 and 213 were delivered to the Compton GRO Science Support Center archive this week. The targets during period 212 were WR 140, Cyg X-1, Cyg X-3, H 1517+65.6, and Fairall 9. The targets during period 213 were the Crab, III Zw 2, and Mrk 509. Preprints from a number of papers by the OSSE team were distributed last week. If you would like to receive preprints and are not already on our distribution list, contact Tina Obrebski (tobrebski@osse.nrl.navy.mil, or 202-767-3165). BATSE BATSE contribution to the GROSSC biweekly report: Over the last week the BATSE pulsed source monitor has been detecting pulsed flux from Cen X-3, OAO 1657-415, Vela X-1 and GX 301-2. BATSE folded-on-board data is currently being collected for PSR 0344+54, PSR 0329+54, the Crab Pulsar, and, PSR J2043+27. Single sweep data is also being collect for pulsar searches. On June 30th an GOES class M2.5 solar flare triggered the batse burst mode. The flare lasted approximately 370 s and was seen above 300 keV. The last M Class flare to trigger BATSE occurred on January 29th. A very intense burst occurred on July 3 at 4:40 UT. The peak BATSE count rate exceeded 100000 cnt/s. The burst lasted approximately 90 s. The preliminary burst location is ra = 143 degrees, dec = 27 degrees (J2000), with an error circle of about 3 degrees radius. As of July 5, BATSE has detected 1037 cosmic gamma-ray bursts out of a total of 2956 on-board triggers in 1169 days of operation. There have been 734 triggers due to solar flares with emission above 60 keV. COMPTEL The COMPTEL instrument is performing well and continues routine observations. Papers by the collaboration recently accepted for publication include reports on "Diffuse Continuum Gamma Rays from the Galaxy Observed by COMPTEL" (Strong et al.), and "COMPTEL Gamma-ray Observations of the Quasars CTA 102 and 3C 454.3" (Blom et al.), both to appear in Astronomy and Astrophysics. Preprints will be available and distributed in the coming weeks. A first announcement of the Second Waterville Valley Workshop on High-energy Solar Phenomena ("The Lessons of Cycle 22 and the Promise of Cycle 23"), to be held from March 6-10, 1995 in Waterville Valley, New Hampshire, was recently distributed electronically. Potential attendees and other interested parties should refer to the full announcement kept on the GRONEWS bulletin board (under "GRO-related meetings"). Finally, now that all interest in the World Cup has evaporated since Team USA was eliminated by Brazil, attention within the team is now focused on the opening stages of the 81st Tour de France, where the field is considered wide open in this new post-Fignon era.