Compton Observatory Science Report #141
Thursday, October 28, 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.  

Normal operations continue.  
There was a maneuver on Monday, October 25, to the attitude of Viewing
Period 305.  The times for this maneuver were 1431Z to 1439Z.  The maneuver
angle was 5.81 degrees, and the HGA boom angle from the equator is now
17.6 degrees.

ARCHIVES
--------
Archive contents-
	BATSE   - Bursts and flares to trigger 1463,
          Four months of daily HER and SHER data (some problems with
             this data are being looked at)
          Additional HER and SHER data up to April 1992 has been 
             received at the SSC and is being installed in the archive.
          Some high-level pulsar light curves have been received at the SSC
        COMPTEL - Periods 1,4,6,7,8,12 and 13 are in the archive.  
          The remainder of periods 1-13 have been received at the SSC and 
             are being processed.
        EGRET   - Periods 0.2-32 are available (Maps and photon lists)
        OSSE    - Periods 1.0 - 15 and 17 are now in the archive (SDB data).
          Period 16 has been received at the SSC and is being processed.  
          Some pulsar data is also available off-line.

BATSE
-----
Dr. Oleg Terekhov of IKI has been visiting in Huntsville this week. He is
discussing with the BATSE team the possiblities for joint Phebus/Granat-BATSE 
gamma-ray burst studies.

The x-ray transient GRO J1719-24 shown only a slight decrease in flux since
its peak near October 1st. The current 20-100 keV flux is approximately 
1.2 Crab. A fit to the flux history gives a lower limit to the decay time
of 130 days.

During viewing period 305 the BATSE pulsar hardware is being used to 
collect 31 ms single sweep data in an effort to detect weak bursts from the
soft gamma repeater SGR 1806-20. Searches are also being conducted in the
lowest energy channel of the DISCLA data. Normal BATSE folded-on-board 
pulsar data is only being collected for the Crab Pulsar. 

COMPTEL
------- 
The COMPTEL instrument continues routine observations.

At the Gamma-Ray Burst Workshop last week in Hunstville the following
results were presented by the collaboration: a report on the new
detection of a number of low-intensity, hard-spectra gamma-ray bursts,
previously unanalysed due to their low flux in hard x-rays, in the
COMPTEL database (Ryan et al.); a summary report on observations of
gamma-ray bursts by COMPTEL during the first year of the GRO mission,
including GRB 910814, which shows evidence for a spectral break at MeV
energies (Hanlon et al.), and a status report on the
BATSE/COMPTEL/NMSU rapid burst response campaign (Kippen et al.)
(Note: with the recent acquisition of new hardware for the rapid
processing of burst data, the goal of the team is to determine an
accurate location for favorable bursts occurring within the field of
view of COMPTEL, within two hours of the receipt of the burst trigger
message from BATSE). In addition, a comparison of data obtained by the
GRO instruments, including COMPTEL, for the burst of 1 June 1991 was
presented by Share et al.

EGRET 
-----
EGRET operations were normal this week.  This was the first
full week of the deep survey.  Because of the nature of the
study the analysis will be long, but it is hoped that the 
rewards will be high.  A large group of abstracts on the 
all-sky survey have been submitted for papers to be presented 
as posters at the January, 1994 AAS meeting.  Several other 
abstracts on EGRET work have been submitted.

OSSE
----
OSSE operations are normal.

In viewing period 305, the Z-axis target is the Virgo sky survey region 
(Key project) centered at (l,b) = (278,+63), and the X-axis target is the
galactic center region, including GRS 1716-249 (PI team).

Members of the OSSE team from NRL, Northwestern University, and Clemson
University were together this week here at NRL to review the instrument
status and progress on recent data analysis, and to begin the organization
for Phase 4 proposal writing.

Data from viewing period 16 was delivered to the Compton GRO Science
Support Center Archive today.  The targets during that time were the Galactic
Center region, NGC 7582, and NGC 253.