CGRO bi-Weekly Status Report

[SHRADER@GROSSC.GSFC.NASA.GOV]

Compton Observatory Science Report #152 Friday, March 4, 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 instruments continue to perform nearly
flawlessly. The operations working group meeting is being held
today, March 3, 1994, at Goddard to discuss details of the
spacecraft status and, among other topics, the prospects (from a
technical perspective) for an extended CGRO mission. At this point,
neither power or propellent management are believed to pose serious
limitations.


                    Science Support Center News


Software for the electronic submission of proposal forms is now
available from the GRO-SSC. It will produce a printable version of
the forms, which can be included with hard copy submission of
proposals, as well as an text file of the relevant data-base
information which you can submit to the SSC via e-mail. Users have
the option of downloading the software to use on there on computers
(VAX/VMS, Sun and DEC Unix are currently supported), or using an
interactive interface through GRONEWS (the latter is to be
implemented shortly). Electronic submission is optional but
encouraged. Look for details on GRONEWS (telnet to 
grossc.gsfc.nasa.gov & login as GRONEWS).

New analysis tools for BATSE data, WINGSPAN, BFITS and DRM_GEN have
been provided to the GRO-SSC by the BATSE team and are available
for GI use. Additional details are given in the BATSE instrument  
report below. 

Also, the IGORE (Interactive Gro Osse Reduction Environment)
package for the analysis of OSSE data has been provided to the SSC
by the OSSE team for public distribution. (via FTP on
grossc.gsfc.nasa.gov /osse/igore - via DECnet copy,
grossc::anon_dir:[osse.igore]).


                        Instrument Reports


OSSE

OSSE operations are normal.

In viewing period 319.0, the Z-axis target is QSO 0716+714 (Key
project), and the X-axis targets are QSO 2251+158 (Key project) and
PKS 2155-304 (Guest Investigator B. McBreen).  The Sun lies near
the OSSE scan plane, and the slewing response to BATSE solar flare
triggers is enabled. 

We commanded OSSE to view both of the recent strong gamma-ray
bursts near the OSSE scan plane, GRB 940217 and GRB 940301, in a
search for afterglow. We monitored the former burst from
approximately +6 hours to +18 hours following the event, and the
latter--which happened to be on the edge of the QSO 0716+714
field--from onset to about +16 hours. OSSE clearly detected
transient emission from the latter burst, and a search for any
persistent emission from either burst is in progress.

Data from viewing period 42 was delivered to the Compton GRO
Science Support Center Archive last week.  The targets during this
period were PKS 2155-304, ESO 141-55, and PSR 1509-58.


EGRET

EGRET operations were normal this bi-weekly period. The percentage
of possible data that was recovered during this period continued to
average about 80%. Interaction with guest investigators remains at
a good level. Delivery of data to the Compton Observatory Science
Support Center remains on the planned schedule. Phase 3 guest
investigators are being contacted as preliminary results become
available. 

The exciting news is that EGRET saw not one, but two gamma-ray
bursts in the spark chamber telescope, the February 18 (Olympic)
burst and the March 1 (Chopin) burst. A late paper has been
submitted for the Washington DC American Physical Society Meeting
(April 1994) on the first burst; we shall probably report the
second one at that meeting also. A good position for the first of
these bursts was obtained and circulated in an IAU telegram. Also
on the subject of bursts, the EGRET paper on the 1993 January 31
(Superbowl) burst appeared in the February 20, 1994 issue of the
Astrophysical Journal Letters on pages L63-L66.
 

COMPTEL

The COMPTEL instrument is performing well and continues routine
observations.

Two strong cosmic gamma-ray bursts occurred within the field of
view of COMPTEL in the last two weeks; the first on February 17th
(the "Olympic Burst"), and the second on March 1st.  Both were
"imaged" and a burst location determined by COMPTEL very shortly
after burst occurrence: within four hours of the BATSE trigger for
GRB 940217, and one hour and forty minutes (a new record!) after
the BATSE trigger for GRB 940301.

This burst-position information was distributed as part of the
BATSE/COMPTEL/NMSU rapid-response campaign to search for burst
counterparts at other wavelengths.  Excerpts from the relevant IAU
Circulars released for these events are given below.

For GRB 940217, IAU Circular No. 5937:

     R. M. Kippen, J. Macri and J. Ryan, University of New
     Hampshire; G. J.  Fishman and C. Meegan, Space Sciences
     Laboratory, NASA/Marshall  Space Flight Center; B. McNamara,
     New Mexico State University; V.  Schoenfelder, Max-Planck
     Institut fur Extraterrestrische Physik; W.  Hermsen, SRON
     Laboratory for Space Research, Leiden; and K.  Bennett,
     Astrophysics Division, Space Science Department, ESTEC,
     European  Space Agency, report: "As part of the
     BATSE/COMPTEL/NMSU Rapid Burst Response  Campaign, COMPTEL has
     imaged a strong cosmic gamma-ray burst that was   first
     detected by the BATSE experiment on Feb. 17.96021 UT.  This
     event is one of the strongest bursts yet observed by BATSE and
     COMPTEL, with several hundred COMPTEL telescope events. 
     Significant emission > 0.72 MeV was measured for > 150 s. 
     Within this interval an intense,  multipeaked structure is
     observed.  The preliminary COMPTEL imaging analysis yields a
     roughly circular uncertainty region centered at R.A. =
     1h59m.8, Decl. = +3d23' (equinox 2000.0; 3-sigma-confidence
     radius 1.2 deg).  Four hours after the burst the COMPTEL
     location was distributed to a world-wide network of
     multiwavelength observatories to search for fading
     counterparts.  We encourage further follow-up observations as
     quickly as possible.  Interested parties should contact B.
     McNamara at New Mexico State University (e-mail
     bmcnamar@nmsu.edu, telephone 505-646-2614)."
 
For GRB 940301, IAU Circular No. 5943:
 
     On behalf of the BATSE/COMPTEL/NMSU Rapid Burst Response
     Campaign  (cf. IAUC 5937, but including now also C.
     Kouveliotou), R. M. Kippen reports: "COMPTEL has imaged a
     strong cosmic gamma-ray burst that was  first detected by the
     BATSE experiment on Mar. 1.84071 UT.  Significant emission >
     0.72 MeV, measured for > 40 s, consists of an intense  single
     peak with substructure.  The preliminary COMPTEL imaging
     analysis based on approximately 170 telescope events yields a
     roughly circular  region centered at R.A. = 6h49m.7, Decl. =
     +63d55' (equinox 2000.0) with uncertainty radii of 1.0
     (2-sigma-confidence) and 1.5 (3-sigma- confidence) deg."  

Finally, the team is soliciting suggestions of appropriate names
for GRB 940301.  "St. David's Burst" has been proposed (by a team
member who prefers to remain anonymous - March 1st being the feast
day of St. David, the patron saint of Wales); other entries are
encouraged.


BATSE 

Flux is still being seen from the x-ray binary A0535+26. The
outburst peaked on February 18 with the 20-40 keV flux reaching
approximately 8 Crab. Since the peak of the outburst the flux has
decline to about 4 Crab at a fairly constant rate.  

The BATSE spectroscopy team at MSFC/UAH announces the availability
of new software at the GROSSC which makes archived BATSE burst
trigger data accessible for analysis.  Burst data delivered to
GROSSC to date has been archived in  Individual Burst DataBases
(IBDBs), which are essentially raw data. The constellation of
analysis programs BFITS, IBDB_REPORT, DRM_GEN, and WINGSPAN 
extract, display, manipulate, background subtract and spectrally
fit selected data.

The program BFITS can convert from the many different data types
and storage formats into a continuous time sequence of spectra,
including background data. Calculation of energy edges of the data
channels is done with the best available calibration information,
and many of the quirks of the raw data are hidden from the user. 
The output format is FITS (Flexible Image Transport System), which
can be transferred reliably to many different computing platforms.

The program IBDB_REPORT displays information about the contents of
an IBDB, e.g., detectors included, angles between the detector axes
and the source, and datatype availability and time coverage.

The workhorse data display and analysis tool for the BFITS produced
FITS data files is WINGSPAN, for WINdows Gamma SPectral ANalysis. 
Among the capabilities of WINGSPAN are the display of time
histories and spectra, the selection of data subsets for display,
creation of a background model and background subtraction,
calculation of hardness ratios, and forward-folding spectral
fitting.  The data are displayed on multiple windows on an
X-terminal and much of the data manipulation is done with a mouse. 
WINGSPAN currently runs on DEC/VMS computers.  Most of the code is
written in Research System's IDL. The spectral fitting portion is
written in FORTRAN. Anyone with an X-windows terminal can run the
software remotely on the GROSSC computing facilities. 

Deconvolution of the observed count spectra requires knowledge of
the detector response.  This knowledge is represented by a Detector
Response Matrix (DRM). Two programs are provided to create DRMs
corresponding to the data in a FITS data file produced by BFITS. 
The program DRM_SPEC_GEN generates DRMs for the BATSE Spectroscopy
Detectors, while DRM_LAD_GEN generates DRMS for the BATSE Large
Area Detectors.