Compton Observatory Science Report #153 Friday, March 17, 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 Compton Observatory and scientific instruments continue to function nominally. An apparent anomaly, leading to limit violations in several telemetry values associated with the COMTPEL "Remote Interface Unit" occurred on March 13. The problem is described in more detail in the COMTPEL Instrument Report below. The anomaly is being investigated by the Flight Operations Team at Goddard, and has had no negative impact on science operations. Science Support Center News In case you hadn't noticed, CGRO proposals for the next cycle are due in less than on month! (April 11, 1994). Its time to start writing. There are a number of potentially useful materials available from SSC for the support of this activity. For instance: * The EGRET team has made available (via anonymous ftp) electronic copy of the first EGRET source catalog (refer to the EGRET report below). This is a potentially valuable resource for those of you who are planning EGRET observations, as it details results from the phase 1 all-sky survey. * A catalog of BATSE burst spectra and software to read and display the data is available on grossc.gsfc.nasa.gov. Also, the BATSE burst catalog listing positions, durations, trigger sensitivities and intensities for approximately the first year of the mission is available on GRONEWS. * Need to know what's been done? Lists of successful proposals for phase 2 and 3 are available on GRONEWS. Additionally, there are statistical breakdowns of accepted programs by topic and proposal type. There are also lists of all awarded targets (by instrument) for phases 2 and 3. This will be supplemented (very soon) with a list of targets which are to be carried over from phase 3 into cycle 4. * There are exposure calculation tools for EGRET and COMPTEL on GRONEWS, as well as a viewing window calculator. These tools allow you for example, to calculate how much effective exposure a source at a given RA and DEC has received over Phases 1-3. * Software for the "electronic" submission of CGRO proposal forms is available. It is not required, but strongly encouraged, as it facilitates our database entry and leads to greater accuracy of all critical proposal information. The software will produce printable forms for you to inspect and include with your hard copy submission, as well as a database file which you can e-mail to the SSC (or have it done automatically). You may download the software to run on your own computer (VAX/VMS, Sun UNIX and Ultrix are supported), or run it interactively on GRONEWS. The distribution kits are on grossc.gsfc.nasa.gov (/nra/gps...). * The Cycle 4 NRA and appendices are available on grossc (PostScript format), or can be browsed on Xmosaic. * And, we even have real data! The present CGRO archive contents are summarized below: BATSE - Triggers to #1466. More will be available soon. 310 days of HER and SHER daily data. Comptel - Periods 1-13.5 (Photon data) Egret - Periods 0.2-44 are available (Maps and photon lists) OSSE - Periods 0.2-31 except 29 are available (SDB data) * Finally, if your preferred mode of information exchange is to talk to a human being, and have proposal related questions, please give us a call. Instrument Reports OSSE OSSE operations are normal. In viewing period 320 (8-15 Mar), the Z-axis target was NGC 7469 (Guest Investigator R. Cameron), and the X-axis target was 3C 120 (Guest Investigator R. Petre). The Sun was not available for slewing on the OSSE scan plane. In viewing period 319.5 (15-22 Mar), the Z-axis target is Mrk 3 (Guest Investigator R. Mushotzky) and the X-axis targets are QSO 2251+158 (Key project) and PKS 2155-304 (Guest Investigator B. McBreen). The Sun is not available for slewing. Data from the following viewing periods have been delivered to the Compton GRO Science Support Center archive in the last two weeks. period targets 36.5 GRO J0422+32, MCG-5-23-16 37 GRO J0422+32, 4C04.77, Mrk 335 43 Mrk 509, Cen A 44 MCG-6-30-15, IC 4329A, PKS 0528+134, QSO 0834-201 204 3C273, 3C279, Gal plane near (l,b) = (355,0) 205 3C273, 3C279, Gal plane near (l,b) = (5,0) EGRET EGRET operations were normal this biweekly period. The percentage of possible data that were recovered during the period continued to average about 80%. Interactions with guest investigators remains at a good level. The "First Energetic Gamma-Ray Experiment Telescope (EGRET) Source Catalog" was accepted for publication by the Astronomical Journal Supplement. This catalog, reporting all of the positive detections from phase 1 and a large number of upper limits for other objects of interest in one place, represents a large effort by many people requiring specialized knowledge and much dedicated effort. Preprints were sent to all scientist who requested them on march 7, 1994. The catalog is also available in electronic form; the text and tables may be accessed in PostScript format by anonymous ftp on the EGRET computer gamma.gsfc.nasa.gov in the directory /pub/catalog. It is emphasized strongly that the text should be read carefully before reading the tables. The contents are as follows: THE FIRST ENERGETIC GAMMA-RAY EXPERIMENT TELESCOPE (EGRET) SOURCE CATALOG C. E. Fichtel, D. L.Bertsch, J. Chiang, B. L. Dingus,J. A. Esposito, J. M. Fierro, R. C. Hartman, S. D. Hunter, G. Kanbach, D. A. Kniffen, P. W. Kwok, Y. C. Lin, J. R. Mattox, H. A. Mayer-Hasselwander, L. McDonald, P. F. Michelson, C. von Montigny, P. L. Nolan, K. Pinkau, H. Rothermel, P. Sreekumar, M. Sommer, E. J. Schneid, D. J. Thompson, and T. Willis The text and tables from the First Energetic Gamma-Ray Experiment Telescope Source Catalog scheduled to be published in the Astrophysical Journal Supplement can be accessed in PostScript format by anonymous ftp on the EGRET computer gamma.gsfc.nasa.gov. Files are located in /pub/catalog. The files containing the text and tables are as follows: catalog_text.ps The First Energetic Gamma-Ray Experiment Telescope Source Catalog text and references. solar_flares.ps solar flares with detected gamma radiation (Table 1) pulsars_strong.ps detected pulsars (Table 2) pulsar_upper_limits.ps upper limits of selected pulsars (Table 3) unid_plane_strong.ps unidentified sources within 10 degrees of the galactic plane, strongly detected (Table 4a) unid_plane_marginal.ps unidentified sources within 10 degrees of the galactic plane, marginally detected (Table 4b) bursts.ps detected gamma ray bursts (Table 5) normal_galaxies.ps detected normal galaxies (Table 6) quasars_strong.ps positive detections of radio loud quasars and BL Lac objects (Table 7) quasars_marginal.ps marginal detections of radio loud quasars and BL Lac objects (Table 8) quasar_upper_limits.ps upper limits of selected radio loud quasars and BL Lac objects and radio galaxies (Table 9) seyfert_upper_limits.p upper limits for selected Seyfert galaxies and radio quiet quasars (Table 10) unid_highlat_strong.ps unidentified sources more than 10 degrees from the galactic plane, strongly detected (Table 11a) unid_highlat_marginal.ps unidentified sources more than 10 degrees from the galactic plane, marginally detected (Table 11b) viewing_periods.ps dates and times of Phase 1 observation periods (Table 12) COMPTEL The COMPTEL instrument continues routine observations. The Flight Operations Team at Goddard is currently investigating anomalies associated with the Remote Interface Unit B (RIU-B), external to COMPTEL, which monitors the state-of-health telemetry from the telescope. The COMPTEL operations group reports that the telescope itself is functioning normally. The RIU problems have had no effect to date on the quality or quantity of flight data obtained from the instrument. The FOT is investigating the possibility of switching COMPTEL to the redundant RIU-A in the near future. In recent scientific results, an extremely intriguing spatial coincidence has been noted between two gamma-ray bursts observed and located within the last year by COMPTEL, GRB 940301 (Chopin) and GRB 930704 (Independence), suggestive of a common source for these events. The error annuli determined for these bursts by the Interplanetary Network overlap within the 2-sigma error boxes derived by COMPTEL. The particulars can be found in IAU Circular No. 5950, excerpted below: GRB 940301 AND GRB 930704, IAU Circular No. 5950 J. M. Ryan, M. McConnell, R. M. Kippen, V. Schoenfelder, K. Bennett, and W. Hermsen for COMPTEL; B. McNamara and T. E. Harrison, New Mexico State University; and H. Pedersen, Copenhagen University Observatory, write: "The COMPTEL team reports the potential repeat of a gamma-ray burst that occurred on 1993 July 4.70075 UT. Based on available data, the COMPTEL position of GRB 930704 is R.A. = 6h43m, Decl. = +62o.5, with a 2-sigma error box covering 28 degE2; the coordinates of GRB 940301 (IAUC 5943, 5944) are R.A. = 6h50m, Decl. = +63o.9, with a 2-sigma error box covering 3 degE2. Without accounting for differential sky exposure, the probability of a 28-degE2 overlap of burst positions is < 1 percent based on the low number of imaged COMPTEL bursts. Preliminary interplanetary annuli (provided by K. Hurley) intersect inside the 2-sigma error boxes of both bursts. If both bursts are assumed to come from the same source, the most likely position of the source, based solely on COMPTEL data, is approximately that of GRB 940301, by virtue of better statistics. For reference, at the center of the combined error boxes and annuli is the star SAOC 13977." Finally, to assist investigators in preparing their proposals a COMPTEL "exposure-calculator" utility is now available on the GRONEWS bulletin board. This utility returns the approximate COMPTEL exposure obtained to date for a user-specified point on the sky. This routine is intended primarily as a proposal-preparation tool, and as a utility to aid in identifying those viewing periods during which maximum COMPTEL exposure was obtained for a particular target. BATSE The following was included in IAU Circular 5945: A0535+26 R. B. Wilson, B. A. Harmon, and G. J. Fishman, Marshall Space Flight Center, NASA; and M. H. Finger, Universities Space Research Association, report for the Compton Gamma Ray Observatory BATSE team: "The strong outburst from A0535+26 (IAUC 5931, 5933, 5934) peaked on Feb. 18, reaching a total intensity of about 8 Crab in the band 20-40 keV. The phase-averaged pulsed flux then was 1.8 Crab (total). The intensity has declined approximately linearly since then, reaching about 4 Crab (total) and 1.1 Crab (pulsed) on Feb. 26. During the peak of its outburst the pulse frequency was increasing at a rate of about 1.2 x 10E-11 sE-2 or P/P(dot) about 25 yr." The x-ray binary A0535+26 is still being detected, with the current 20-40 keV flux being approximately 0.5 Crab. The CONT data energy channel edges, which had been changed to improve energy resolution near 100 keV, have been restored to their previous values. Cygnus X-1, which had been at a very low flux level since early January, has recently increased in flux. Between 25 February and 9 March the 45-110 keV flux increased from about 0.2-.04 photons/cm^2/s to 0.11 photons/cm^2/s. The latter flux level is consistent with the gamma-2 state of Cygnus X-1. Pulsar data is currently being collected for the Crab pulsar, PSR 1259-63, Cen X-3, PSR 1509-59 and PSR 1556-44. Single sweep data with 31 ms resolution is begin collected for pulsar searches using LAD 3. As of March 14th, BATSE has detected 933 cosmic gamma-ray bursts out of a total of 2776 on-board triggers in 1056 days of operation. There have been 729 triggers due to solar flares with emission above 60 keV.