Compton Observatory Science Report #162, Friday July 2, 1994 Chris Shrader, Compton Observatory Science Support Center Questions or comments can be sent to the CGRO 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 A draft version of the Cycle-4 timeline was formulated last week and is now undergoing detailed constraint checking by the Goddard Flight Dynamics branch. The timline development was a collaborative effort between representatives from the PI Teams, the Guest Investigator community and the CGRO-SSC. The CGRO-SSC can now support the use of the XSPEC program for spectral analysis of EGRET data. XSPEC spectral fitting program used widely within the X-ray astronomy community, which offers many spectral models. It is also possible to develop new models to use with XSPEC. Congratulations to BATSE Principal Investigator, Dr. Gerald Fishman, who was among a small group of distinguished NASA scientists invited the White House this week as part of a 25'th Anniversary celebration of the Apollo moon landing. Instrument Reports EGRET EGRET operations were normal this biweekly period. Delivery of data to the CGRO-SSC is on schedule. Interaction with Guest Investigators has slowed a bit due to their summer vacations, but continues. Several major papers are nearing completion and others have recently been submitted to scientific journals. Hence, if all goes well, with typical review cycles there should be a number of new papers, or at least preprints, available by the end of the year, with some interesting general conclusions worthy of consideration. OSSE OSSE operations are normal. In viewing period 335.0 (12-18 July), the Z-axis target was PSR J0437-47 (Guest Investigator M. Bailes) and the X-axis target was Geminga (PI team). When both targets were occulted, OSSE observed SMC X-1 and QSO 0954+658. The Sun was not available on the OSSE scan plane. In viewing period 334 (18-25 July), the Z-axis target is the galactic plane (Key project) near (l,b) = (15,0), and the X-axis target is Her X-1 (Guest Investigator M. Kunz). When both targets are occulted, OSSE observes QSO 0954+658. The Sun is not available on the OSSE scan plane. A small contingent from the OSSE team is attending the 30th COSPAR meeting in Hamburg this week. Highlights of recent results are being presented, in particular, the interesting spectral behavior of A0535+26, Cyg X-1, and Seyfert galaxies. Data from viewing periods 214, 215, and 216 were delivered to the Compton GRO Science Support Center archive this week. The targets during period 214 were 1E 1740.7-2942 and MCG-2-58-22. The targets during period 215 were Cen A, GRO J1317-44, SN 1987A, and PSR 0540-69. The targets during period 216 were SN 1993J and M31. BATSE A revision to the BATSE flight software was loaded on July 19. The most significant change is that the solar flare trigger signal now encodes the burst elevation angle. This will allow OSSE to slew to bursts automatically. The BATSE data is being search for hard x-ray and gamma-ray emission due to the Shoemaker-Levy impacts on Jupiter, but so far no emission has been detected. Over the last week the BATSE pulsed source monitor has detected pulsed flux from Her X-1, 4U 1626-67, OAO 1657-415, Vela X-1 and GX 301-2. BATSE folded-on-board data is currently being collected for the Crab Pulsar, Her X-1, and PSR J0437-471. As of July 18th, BATSE has detected 1058 cosmic gamma-ray bursts out of a total of 2985 on-board triggers in 1182 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. A cosmic gamma-ray burst was recorded within the field of view of COMPTEL on 8 July. The position of the burst was determined within a few hours of occurrence, and this information distributed via the BATSE/COMPTEL/NMSU rapid-response network. The details for this particular event follow: TITLE : COMPTEL BURST POSITION NOTICE: GRB940708 NOTICE_DATE: Sat Jul 9 01:16:32 GMT 1994 ORIG_SENDER: burst@comptel.unh.edu ***************************************************** BURST_DATE : 9541 TJD; 8-JUL-1994 BURST_TIME : 74526.00 SEC; 20:42: 6 UT BURST_SCZEN: 6.0 Deg. BURST_SCAZI: 139.0 Deg. BURST_CLASS: Weak (Approx 37 events) ***************************************************** COORD_J2000: [RAsc Decl] [RAsc Decl] ============ =============== ====================== MAXLIK_POS : [300.2d 22.3d] = [20h 0m40s 22d15m11s] ----------------------------------------------------- ERRBOX1_POS: [299.0d 22.9d] = [19h55m49s 22d51m12s] ERRBOX2_POS: [300.5d 23.5d] = [20h 2m 1s 23d27m15s] ERRBOX3_POS: [301.4d 21.5d] = [20h 5m26s 21d32m45s] ERRBOX4_POS: [299.8d 21.0d] = [19h59m17s 20d57m15s] ***************************************************** COORD_B1950: [RAsc Decl] [RAsc Decl] ============ =============== ====================== MAXLIK_POS : [299.7d 22.1d] = [19h58m38s 22d 6m29s] ----------------------------------------------------- ERRBOX1_POS: [298.5d 22.7d] = [19h53m49s 22d42m49s] ERRBOX2_POS: [300.0d 23.3d] = [20h 0m 1s 23d18m27s] ERRBOX3_POS: [300.8d 21.4d] = [20h 3m23s 21d23m44s] ERRBOX4_POS: [299.3d 20.8d] = [19h57m14s 20d48m38s] There will be a general team meeting of the collaboration next week in Leiden, The Netherlands. Finally, while hopes for an all-COMPTEL final in the World Cup were never fully realized, recent events elsewhere in the Solar System have helped place those results in the proper perspective (though there are still some dissenting opinions within the team).