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.