Compton Observatory Science Report #148 Friday, January 7, 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 Spacecraft and all subsystems continue to perform nominally. The current Z-axis target is PSR 1259-63 which is a 47-ms pulsar in an eccentric binary orbit about a Be star primary. The neutron star is currently undergoing perisaton passage - its orbital period is 3.4 years. Science Support Center News The Science Support Center staff are planning a series of demonstrations for the forthcoming AAS meeting. An approximate schedule of the planned demonstrations follows: Wednesday: 1:45 PM SSC Data Archive Thursday: 9:30 AM EGRET Analysis Tools Thursday: 1:45 PM Gamma Core, SSC Quick Look Tools Friday: 1:45 PM OSSE Analysis Tools (IGORE) The CGRO Cycle 4 NRA will be issued shortly. The due date for proposals will be April 10, 1994, with Cycle 4 observations commencing on 4 October 1994. Copies of the NRA and appendices will be available electronically on GRONEWS. Instrument Reports OSSE OSSE operations are normal. In viewing period 313, the Z-axis target was the Virgo sky survey (Key project) near galactic coordinates (l,b) = (289,+79), and the X-axis target was the galactic center region (PI team). The Sun was accessible along the scan plane, and OSSE slewed to the Sun in response to BATSE triggers at the following times (TJD): 9348.7858, 9351.2427, 9352.0345, 9352.3463, 9352.9219, and 9353.5150. In viewing period 314, the Z-axis target is the binary pulsar PSR 1259-63 (Guest Investigator M. Tavani), and the X-axis target is the nova N Her 1991 (Guest Investigator S. Starrfield). The Sun is not accessible along the scan plane, and the slewing response is disabled. Data from viewing periods 25, 27, and 31 will be delivered to the Compton GRO Science Support Center Archive today. The targets during vp 25 were the galactic center region, Mrk 841, and NGC 7582. During vp 27, the targets were 4U 1543-57 and NGC 7314. During vp 31, the targets were MCG+8-11-11, PKS 0548-322, and SN 1987A. EGRET EGRET observations were normal this week. It was a relatively quiet period in terms of interactions with the outside community because of the holidays. However, there was substantial work here in preparation for the forthcoming American Astronomical Society Meeting wher many results summarizing the all-sky survey will be presente for the first time. COMPTEL The COMPTEL instrument is performing well and continues routine observations. Final preparations are underway for team presentations at next week's meeting of the AAS in Washington, D.C. The collaboration will be presenting its latest results on the topics of gamma-ray line spectroscopy (Bloemen et al.), x-ray binaries (McConnell et al.), and active galaxies (Bennett et al.). BATSE The following report was published in IAU circular No. 5915: GX 339-4 B. A. Harmon, W. S. Paciesas, S. N. Zhang, G. J. Fishman, and M. H. Finger, Marshall Space Flight Center, NASA, report for the Compton Observatory's Burst and Transient Source Experiment (BATSE) Team: ``The black-hole candidate GX 339-4 has again entered its hard (low) emission state, being detected by earth occultation beginning in late December 1993. Its intensity has increased gradually and is currently at about 0.2 Crab (Dec. 30-1994 Jan. 1) in the band 20-100 keV with a hard spectrum. Outbursts of GX 339-4 beginning in late June 1991 (IAUC 5327) and early September 1992 (IAUC 5647), and now in December 1993, indicate an interval between hard x-ray outbursts of about 440 +/- 30 days. This is a strong indication of long-term periodicity in this suspected-but-unproven binary system. If the periodicity is associated with the binary orbit, GX 339-4 does not fit conveniently into the canonical model of a low-mass, x-ray binary." On January 5th an anomaly occurred in BATSE detector module 3 that caused the loss of its 16 and 128 channel LAD data types. The problem is thought to have been due to a latch-up in the monolithic charge to time conversion (MQT) electronics. The power to the module was cycled on January 6th which restored normal behavior. Three simular events have occurred since launch, all with module 3. BATSE folded-on-board pulsar data is currently being collected from the Crab pulsar, PSR 0950+08, PSR 0818-13, and PSR 1259-63. The pulsar hardware is also being used to collect 31 ms single sweep data for pulsar searches.