------------------------------------------------------------------ Compton Observatory Science Report #158, Friday, May 27, 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 Observatory, scientific instruments and all spacecraft subsystems continue to function nearly flawlessly. Science Support Center News Several new Xmosaic services are available from the SSC: Batse Burst table: The Batse burst table, also available on GRONEWS (see the BATSE Instrument Report below) has now been placed on our BATSE Services page. In addition to the burst table itself one can "click" on a trigger number to obtain a simple light curve and summary information about each burst. For those of you who want to add it to your hotlist the reference is: http://enemy.gsfc.nasa.gov/cossc/bursttable.html Enjoy! The CGRO-SSC Users Guide is also available on Xmosaic from the CGRO-SSC home page. A CD Rom containing the Phase-1 EGRET Sky Survey data, and software for reading it and performing basic analysis, has been produced by the SSC staff. It will be distributed at the Minneapolis AAS meeting next week. A model of the high-energy diffuse emission has been provided to the SSC by the EGRET team (see the EGRET report below). It has been installed in our software for use by guest investigators or is available for use with other software. The Second Compton Symposium Proceedings have been printed and are now being mailed out to all meeting participants. Instrument Reports EGRET EGRET operations were normal during this biweekly period. The data reduction and analysis is progressing as planned. Interaction with guest investigators remains at a good level. Delivery of data to the CGRO-SSC is on schedule. Several papers on EGRET results will be presented at the American Astronomical Society Meetings next week. One of these will be on the remarkable high-energy gamma ray results related to the February 17, 1994 burst mentioned in this report four weeks ago. The high-energy gamma-ray diffuse emission model of Bertsch, Dame, Fichtel, Hunter, Sreekumar, Stacy, and Thaddeus with recent improvements by the same group has been transferred to the CGRO-SSC in FITS format for anyone who wishes to use it. Additional refinements with the relevant references will be transferred to the SSC in the near future. Scientists are, of course, still free to use any model they choose. OSSE OSSE operations are normal. In viewing period 328 (24-31 May), the Z-axis target is Cyg X-3 (PI team), and the X-axis targets are PSR 0611+22 (Guest Investigator J. Cordes) and 4U 0115+63 in its current outburst. The Sun is not available on the scan plane, so the slewing response to BATSE solar flare triggers is disabled. For the first 24 hours of this viewing period, we directed two detectors to monitor Cyg X-1. Preliminary analysis of these data indicate that the source has returned to a flux level and temperature characteristic of most OSSE observations of Cyg X-1, in contrast to the low-flux, low-temperature spectrum we reported in February (IAU Circ 5930). Data from viewing periods 209 and 210 were delivered to the Compton GRO Science Support Center archive this week. The targets during period 209 were 2CG010-31, Cyg X-1, and 3C390.3, and during period 210 were 1E1740.7-2942 and MCG-2-58-22. BATSE The second BATSE catalogue of gamma-ray bursts is now available through the Gamma-Ray Observatory Science Support Center. The catalogue comprises 585 bursts observed through 1993 Mar. 9 and includes the previously released 1B catalogue. To access the catalogue, INTERNET users should type 'telnet grossc.gsfc.nasa.gov'; DECNET users should type 'set host grossc'. The login name is 'gronews', and no password is required. The following was included in IAU Circular 5990: 4U 0115+634 D. M. Scott, M. H. Finger, R. B. Wilson, and T. A. Prince report for the Compton Gamma Ray Observatory BATSE pulsar team: "Pulsed hard x-ray flux in the energy range 20-70 keV is currently being detected from the x-ray binary 4U 0115+634. This is the second outburst of this source observed by BATSE, the first occurring in April 1991. In the current outburst, pulsed flux was first detected on 1994 May 8. An intrinsic pulse period of 3.6145107 +/- 0.0000010 s and a period derivative of (5.9 +/- 1.9) x 10E-11 were determined for epoch May 13.0 UT. The phase-averaged pulsed flux, averaged over 20-40 keV, was about 45 mCrab (total) on May 15. The spectrum is well fit by an optically thin thermal bremsstrahlung model A/E exp(-kT), with kT = 16 +/- 4 keV, and a flux at 35 keV of (2.0 +/- 0.2) x 10E-4 photon cmE-2 sE-1 keVE-1." The source is still being observed. The pulsed flux has gradually been increasing since May 15, with the total increase approximately 25%. As of May 22, BATSE has detected 993 cosmic gamma-ray bursts out of a total of 2883 on-board triggers in 1125 days of operation. There have been 732 triggers due to solar flares with emission above 60 keV. COMPTEL The COMPTEL instrument is performing well and continues routine observations. The latest cosmic gamma-ray burst to occur within the field of view of COMPTEL was recorded on May 20, 1994 (name TBD). The first determination of burst location, based on approximately 55 COMPTEL telescope events, was distributed through the BATSE/COMPTEL Rapid Response Network within 3 hours of burst occurrence. The most recent burst location determined from the COMPTEL data, which agrees well with the preliminary IPN location annulus, is given below, along with the coordinates of the one-sigma error box: ***************************************************** BURST_DATE : 9492 TJD; 20-MAY-1994 BURST_TIME : 1298.00 SEC; 0:21:38 UT BURST_SCZEN: 23.5 Deg. BURST_SCAZI: 219.8 Deg. BURST_CLASS: Medium (Approx 55 events) ***************************************************** COORD_J2000: [RAsc Decl] [RAsc Decl] ============ =============== ====================== MAXLIK_POS : [324.6d 7.8d] = [21h38m14s 7d45m48s] ----------------------------------------------------- ERRBOX1_POS: [325.7d 8.9d] = [21h42m42s 8d56m13s] ERRBOX2_POS: [325.5d 6.2d] = [21h41m52s 6d12m56s] ERRBOX3_POS: [323.5d 6.4d] = [21h33m54s 6d21m36s] ERRBOX4_POS: [323.7d 9.1d] = [21h34m40s 9d 4m57s] ***************************************************** COORD_B1950: [RAsc Decl] [RAsc Decl] ============ =============== ====================== MAXLIK_POS : [324.0d 7.5d] = [21h35m54s 7d31m39s] ----------------------------------------------------- ERRBOX1_POS: [325.1d 8.7d] = [21h40m22s 8d41m53s] ERRBOX2_POS: [324.9d 6.0d] = [21h39m31s 5d58m38s] ERRBOX3_POS: [322.9d 6.1d] = [21h31m32s 6d 7m39s] ERRBOX4_POS: [323.1d 8.8d] = [21h32m21s 8d50m58s] ***************************************************** Investigators who do not routinely receive such reports through the BATSE/COMPTEL Rapid Response Network, and who wish to be added to the distribution list for future notices, should contact either Dr. Bernie McNamara at NMSU (bmcnamar@nmsu.edu) or Dr. Jim Ryan at UNH (jryan@unh.edu) for further details.