Compton Observatory Science Report #117 Thursday, April 29, 1993 Eric Chipman, Compton Observatory Science Support Center Questions or comments can be sent to the Compton SSC. Phone 301/286-7764, e-mail SPAN GROSSC::CHIPMAN, Internet chipman@grossc.gsfc.nasa.gov. The Compton spacecraft continues normal operations. No maneuvers took place this week. Due to lack of guide stars at the originally planned pointing, the attitude for period 219.4 (from May 5 to May 7) has been modified by about 4 degrees. The targets remain the same. The new attitude is: z-axis: RA = 245.35, DEC = -27.22 x-axis: RA = 341.26 DEC = -11.31 The optical disk jukebox for the archive memory at the Compton Science Support Center arrived this week. This will enable us to maintain at least one year of Compton data on-line for archival users, or a somewhat longer period of selected high-usage data. BATSE ----- As of April 27th, BATSE has detected 629 cosmic gamma-ray bursts out of a total of 2214 on-board triggers in 735 days of operation. There have been 644 triggers due to solar flares with emission above 60 keV. COMPTEL ------- The COMPTEL experiment is performing well and continues routine observations. The COMPTEL operations group is making final preparations for the orbital reboost of GRO, scheduled for June 1993. During the test burns of the spacecraft propulsion system starting next week, the COMPTEL instrument will be place in a "safe" mode, with all primary detector high voltages turned off, as is done during passages through the SAA. EGRET ----- EGRET operations were normal this week. Considerable progress has been made toward the completion of the basic Phase 1 data analysis and work on the catalog on the Phase 1 results. Our goal is to submit the Phase 1 catalog for publication in about three months. Many of the results will be presented at the June AAS meeting along with some of the highlights of Phase 2. Neil Gehrels, Jay Norris and Carl Fichtel have been working hard on the Second Compton Symposium. If you have not received an announcement and wish one, contact Jay Norris, code 668, at Goddard. If you are an invited speaker and have not yet sent your final title to Carl Fichtel, please do so. OSSE ---- OSSE operations continue to be normal. For viewing period 218, the Z-axis target is NGC 4151 (PI team), and the X-axis target is the recent supernova SN 1993J. The Sun is no longer near OSSE's scan plane, and the slewing response to BATSE flare triggers was disabled on 26 April. Since the last status report, there have been no slews to the Sun in response to BATSE flare triggers. The data from this second supernova pointing are begin analyzed as they arrive at NRL. OSSE team members are continuing to look for evidence of low-energy gamma-ray continuum as well as nuclear line emission. Data from viewing period 7.0 was delivered to the GRO Science Support Center Archive this week. The targets for this Target of Opportunity pointing were Cyg X-3, Cyg X-1, and M82.