Compton Observatory Science Report #126 Thursday, July 1, 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. Science operations are continuing. There was a maneuver on Tuesday, June 29, to the attitude of period 228. The times of the maneuver were 1404Z to 1442Z, and the total maneuver angle was 130 degrees. The HGA boom angle with respect to the equator is now 71 degrees. There was a previous maneuver on Saturday, June 19, to the attitude of period 227, which was not summarized in last week's report. Note that this period had been scheduled to start later, on June 28 or 29, but was moved ahead when the reboost was interrupted. The z-axis and x-axis targets for this period were the Galactic Center and the Coma Cluster, respectively. The times of the maneuver were 1303Z to 1330Z. The maneuver angle was 78 degrees, and the boom angle from the equator after the maneuver was 46 degrees. Analyses of the reboost situation continue. A decision on a choice of procedure will take several days at least. BATSE ----- The First BATSE Burst Catalog paper has been submitted for publication in the Astrophysical Journal. This catalog provides extensive data, including time history plots, of the 260 bursts observed by BATSE during its first year of operation. After acceptance, preprints will be mail to everyone on the BATSE preprint mailing list. If you would like to be added to this list, email Dannah McCauley at McCauley@ssl.msfc.nasa.gov on internet or SSL::MCCAULEY on SPAN. In viewing period 227 BATSE folded-on-board data is being collected for the Crab pulsar, Her X-1, PSR 1919+21 and PSR 1055-52. As of June 29th, BATSE has detected 691 cosmic gamma-ray bursts out of a total of 2318 on-board triggers in 798 days of operation. There have been 662 triggers due to solar flares with emission above 60 keV. COMPTEL ------- Pending decisions on the revised dates for the orbital reboost maneuver for the GRO spacecraft, the COMPTEL instrument continues to carry out routine observations. There will be a meeting of the COMPTEL collaboration next week at MPE in Garching, Germany to review the instrument performance to date, and the status of flight data processing and associated scientific analysis. In other items of interest: the countdown for the 80th Tour de France is underway (Fignon is rested and ready). EGRET ----- EGRET operations were normal this week. The instrument continues to collect data and will until it is turned off for the reboost. Abstracts for eight talks and ten poster papers were submitted for the Second Compton Symposium. Work on a series of papers summarizing the Phase I results is now in progress along with some on new results from Phase II. Guest Investigator interactions were at a normal level this week. We are also seeing increased interest in informal cooperation. We feel that this activity is going well. OSSE ---- OSSE operations have returned to normal. All four detector elevation drive readout potentiometers are operating properly. For viewing period 228, the Z-axis target is the recent supernova SN 1993J, and the X-axis target is the radio pulsar PSR 0740-28 (PI team). Because the Sun is not available on the OSSE scan plane, the slewing response to BATSE solar flare triggers is disabled. However, if the recent solar activity continues as the Sun approaches OSSE's field of view, we may activate the slewing later in the viewing period. Data from viewing period 9.5 were delivered to the Compton Observatory Science Support Center archive today. Targets during that time were the X-ray binary Her X-1 and the BL Lac Mrk 421.