Compton Observatory Science Report #138 Thursday, October 7, 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. Reboost operations are proceeding this week, and are scheduled to continue to October 17. The two reboost burns so far this week, on Monday and Wednesday, were successful and nominal in the thrust obtained, according to the data we have. The following report was received Wednesday from Project Scientist Neil Gehrels: The second reboost maneuver was again successful today. The maximum attitude error after the burn was small (about 13 degrees) and corrected within a few minutes after the burn. Monday's reboost gave us the expected gain of about 6 km in mean altitude, and today's burn did about the same. On Friday, October 1, there was a maneuver to close to the attitude to be used for the reboost. This attitude gave the spacecraft a stable thermal environment for the reboost period, but did allow some science up to October 4. The maneuver times were 1444Z to 1457Z, the maneuver angle was 30.05 degrees, and the final HGA boom-equator angle was 29.61 degrees. On Monday, October 4, there was a maneuver to align the orbital velocity vector with the thrust vector during the planned 1-minute reboost burns of the B-side OATS. The maneuver times were 1237Z to 1246Z, the eigenaxis maneuver angle was 14.02 degrees, and the HGA boom-equator angle is now 16.73 degrees. ARCHIVES -------- Archive contents- BATSE - Bursts to trigger 1466, flares to trigger 1454, four months of daily HER and SHER data. Additional flare data up to trigger 1466 and corresponding HER and SHER data 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. 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 0.2-11 are available (SDB data). Pulsar data also available off-line. BATSE ----- BATSE is be operating normally during the most of the reboost phase. BATSE is begin placed in a low power mode (with detectors off) for each burn, and then commanded to normal operations after the burn. The low power modes for the burns for so far have lasted an average of 4.5 hours. The Soft Gamma-ray Repeater SGR 1806-20 has triggered the BATSE detectors four times in the past week. The first three were on Sept 29, as reported in IAU Circ. 5875. The fourth occurred on Oct. 5. All four events from the SGR were short events, with no emission observed observed above 100 keV. The SGR's are distinct from the classical gamma-ray bursts. Classical GRB's typically emit most power above several hundred keV and are not seen to repeat. The transient source GROJ 1719-24 = GRS 1716-249 remains bright (about 1.5 Crab in the 20-100 keV band) as of October 5. The risetime to maximum was about 6-7 days with a peak flux of 1.6 Crab on October 2 and 3. The spectrum is hard with power law index of -2.0 (20-100 keV band). Statistics relating to the isotropy of gamma-ray bursts have now been computed for 743 bursts. The dipole moment in Galactic coordinates is 0.018, versus -0.013 +/- 0.021 expected for BATSE's sky exposure. The quadrupole moment in Galactic coordinates is -0.012, versus -0.005 +/- 0.011 expected for BATSE's sky exposure. The errors represent the statistical uncertainty for a sample size of 743 events. The nearest neighbor distribution and the two point angular correlation distribution are both consistent with isotropy. Details will be provided at the Huntsville Burst Workshop. The preliminary program for the upcoming Huntsville Gamma Ray Burst Workshop, Oct. 20-22, has been mailed, listing over 180 papers. The enormous response to the Workshop indicates the high level of interest in gamma-ray bursts. The large response will also tax the available time and space available to the Workshop. BATSE team members from Huntsville, UCSD and GSFC will present numerous talks and posters on recent a variety of topics. COMPTEL ------- The COMPTEL instrument was placed in a low-power mode last Friday, 1 October, in anticipation of the orbital reboost of the GRO spacecraft, currently in progress. COMPTEL will remain "off" for the duration of the reboost maneuver. There will be a general team meeting of the COMPTEL collaboration next week at ESA/ESTEC, in Noordwijk, The Netherlands. EGRET ----- EGRET operations were normal this week until the instrument was placed in a low power mode for the reboost. We are looking forward to the deep survey to begin after the reboost; this study, which is the result of a key proposal, should represent a significant step in the understanding of the high energy gamma ray emission from AGN's. A major effort involving many institutions and observations at several wavelengths will be undertaken during this period. I was pleased to learn that several theorists are taking the challenge that I issued two weeks ago seriously; so I shall repeat it here. The challenge is "...to determine how such large numbers of relativistic particles that presumably lead to the great luminosity of high energy gamma rays are accelerated in an AGN in the first place." Carl Fichtel OSSE ---- OSSE operations are normal. For viewing period 303.4 (October 1-4), the attitude of the spacecraft was moved near the reboost attitude for thermal reasons and the OSSE Z-axis and X-axis targets were Cyg X-1 and 3C 273, respectively. During this period, OSSE responded to BATSE solar flare triggers with slews to the Sun on the following five occasions (TJD=Truncated Julian Day): TJD 9261 (Oct. 1) at 15440 seconds UTC, TJD 9261 (Oct. 1) at 81165 seconds UTC, TJD 9262 (Oct. 2) at 43912 seconds UTC, TJD 9263 (Oct. 3) at 33897 seconds UTC, TJD 9263 (Oct. 3) at 45750 seconds UTC. During viewing period 303.5 (October 4-17), the reboost period, OSSE will be placed in a low-power mode several times (e.g. during burn maneuvers which occurred on October 4 and October 6 and are scheduled to occur on October 8, and each day between October 11 and 15). When in normal operating mode, OSSE will perform several engineering tests and science objectives, including monitoring the Sun with the OSSE main detectors and using the OSSE shield elements to collect data on the recently discovered hard x-ray transient GRS 1716-249 = GRO J1719-24 (cf. IAU Circ. 5874). This week, members of the OSSE Team are presenting recent OSSE results at a workshop on galactic black hole candidates and active galactic nuclei in Koninki, Poland. Recent OSSE results will also be presented at the 4th Annual October Astrophysics Conference on the Evolution of X-Ray Binaries next week at the University of Maryland. Data from viewing period 15 will be delivered this week to the Compton GRO Science Support Center Archive. Targets during this period were NGC 1275 and Cygnus X-1. Other Items: ------------ Yet another revision of the Phase 3 Timeline has now been developed; this includes the actual attitude for Oct 1-4 during the thermal preparation for the first reboost period, and the allocation of the second part of the reboost in November-December. COMPTON PHASE 3 VIEWING PLAN AS OF OCTOBER 1, 1993 Z-axis is pointing direction for COMPTEL and EGRET. OSSE points in X-Z plane. RA and DEC are J2000. VIEW +Z-AXIS GRO Z-AXIS GALACTIC GRO X-AXIS OSSE PRIMARY TARGET OSSE SECONDARY TARGET PER. START TARGET RA DEC LONG LAT RA DEC TARGET RA DEC TARGET RA DEC 301 08/17/93 VELA PULSAR 128.92 -45.18 263.59 -2.74 161.94 39.80 VELA PULSAR 128.92 -45.18 QSO 1028+313 157.74 31.05 232* 08/24/93 GAL 348+00 258.02 -39.35 347.50 0.00 188.46 23.07 GPLANE 347.5 258.02 -39.35 MRK 421 166.11 38.21 232.5* 08/26/93 GAL 348+00 258.02 -39.35 347.50 0.00 182.10 16.48 GPLANE 347.5 258.02 -39.35 NGC 4388 186.44 12.66 302.0 09/07/93 N CYG 1992 307.63 52.63 89.13 7.82 202.99 10.92 N CYG 1992 307.63 52.63 NGC 5548 214.50 25.13 302.3 09/09/93 GX 1+4 258.64 -22.70 1.41 9.26 180.21 25.63 GX 1+4 263.01 -24.75 VIRGO 298+82 192.31 19.75 303.0 09/21/93 GRS 1009-45 157.58 -42.88 277.21 12.83 217.43 28.41 GRS 1009-45 153.25 -45.40 NGC 5548 214.50 25.13 303.2 09/22/93 N CYG 1992 307.63 52.63 89.13 7.82 202.99 10.92 N CYG 1992 307.63 52.63 NGC 5548 214.50 25.13 303.4 10/01/93 PRE-REBOOST 270.79 37.87 64.33 25.27 182.17 -1.77 CYG X-1 299.58 35.20 3C 273 187.28 2.05 303.5 10/01/93 REBOOST 303.7 10/17/93 N CYG 1992 307.63 52.63 89.13 7.82 202.99 10.92 N CYG 1992 307.63 52.63 NGC 5548 214.50 25.13 304 10/19/93 VIRGO 278+59 180.01 -1.62 277.60 58.70 270.91 -28.89 VIRGO 278+59 180.01 -1.62 G CENTER 0+0 266.40 -28.94 305 10/26/93 VIRGO 278+63 181.58 2.06 277.70 62.70 270.38 -30.16 VIRGO 278+63 181.58 2.06 G CENTER 0+0 266.40 -28.94 306 11/02/93 VIRGO 278+67 183.29 5.68 278.20 66.70 271.03 -21.61 VIRGO 278+67 183.29 5.68 PSR 1800-21 270.96 -21.61 307 11/09/93 VIRGO 269+69 181.19 9.53 268.69 69.24 252.79 -61.99 VIRGO 269+69 181.19 9.53 GPLANE 324 232.93 -56.20 308 11/16/93 VIRGO 283+75 187.61 12.59 283.22 74.65 258.54 -55.65 VIRGO 283+75 187.61 12.59 GPLANE 332 243.91 -50.82 309 11/22/93 REBOOST 310 12/02/93 GEMINGA 98.48 17.77 195.14 4.27 201.46 35.02 GEMINGA 98.48 17.77 NGC 4151 182.63 39.41 311 12/13/93 VIRGO 284+75 187.69 12.41 283.70 74.50 272.61 -21.93 VIRGO 284+75 187.69 12.41 PSR 1800-21 270.96 -21.61 312 12/20/93 VIRGO 281+71 185.52 9.12 280.50 70.70 271.83 -21.80 VIRGO 281+71 185.52 9.12 PSR 1800-21 270.96 -21.61 313 12/27/93 VIRGO 289+79 190.10 16.12 289.30 78.70 270.42 -30.20 VIRGO 289+79 190.10 16.12 G CENTER 0+0 266.40 -28.94 314 01/03/94 GAL 304-01 195.69 -63.83 304.18 -0.99 277.55 3.99 PSR 1259-63 195.69 -63.83 N HER 1991 281.63 12.24 315 01/16/94 GAL 304-01 195.69 -63.83 304.18 -0.99 282.83 1.41 PSR 1259-63 195.69 -63.83 G CENTER 0+0 266.40 -28.94 316 01/23/94 CEN A 201.37 -43.02 309.52 19.42 310.35 -19.21 CEN A 201.37 -43.02 CTA 102 338.15 11.73 317 02/01/94 NGC 1068 37.41 10.61 158.48 -45.38 306.06 7.18 3C 120 68.29 5.35 CTA 102 338.15 11.73 318 02/15/94 GAL 015+06 268.94 -13.18 14.79 6.00 5.76 -26.89 GPLANE 15 274.47 -15.90 NGC 253 11.88 -25.29 319 02/22/94 QSO 0716+714 110.48 71.34 143.98 28.02 341.13 12.08 QSO 0716+714 110.48 71.34 PKS 2155-304 329.72 -30.22 320 03/08/94 GAL 083-45 345.81 8.87 83.09 -45.47 76.45 4.13 NGC 7469 345.81 8.87 3C 120 68.29 5.35 321 03/15/94 GAL 357-11 276.44 -37.11 356.85 -11.29 349.25 21.35 1H 1822-371 276.44 -37.11 QSO 2251+158 343.49 16.13 322 04/01/94 MRK 421 157.18 32.26 194.76 58.73 14.17 51.67 QSO 1028+313 157.74 31.05 MRK 3 93.91 71.03 323 04/15/94 GAL 357-11 276.44 -37.11 356.85 -11.29 349.25 21.35 1H 1822-371 276.44 -37.11 QSO 2251+158 343.49 16.13 324 04/19/94 GAL 016+05 270.89 -12.83 16.03 4.51 358.13 11.96 GPLANE 15 274.47 -15.90 NGC 7469 345.81 8.87 325 04/26/94 GAL 147-09 49.07 46.94 147.04 -9.04 67.24 -41.60 GT 0236+610 40.14 61.22 SN 1987A 83.86 -69.27 326 05/10/94 NGC 3227 156.69 31.65 195.92 58.31 47.37 28.24 QSO 1028+313 157.74 31.05 NRAO 140 54.13 32.31 327 05/17/94 GAL 083-45 345.81 8.87 83.09 -45.47 81.19 31.01 NGC 7469 345.81 8.87 NRAO 140 54.13 32.31 328 05/24/94 PSR 1951+32 298.76 28.07 64.87 -0.03 69.89 50.97 CYG X-3 308.11 40.96 PSR 0611+22 93.56 22.42 329 05/31/94 GAL 253-42 69.26 -47.25 253.40 -42.00 88.04 41.18 PSR J0437-47 69.26 -47.25 CRAB PULSAR 83.52 22.02 330 06/07/94 GAL 018+00 275.93 -13.26 18.00 0.00 341.41 60.41 GPLANE 18 275.93 -13.26 GT 0236+610 40.14 61.22 331 06/14/94 PSR 1951+32 298.76 28.07 64.87 -0.03 69.89 50.97 CYG X-3 308.11 40.96 PSR 0611+22 93.56 22.42 332 06/21/94 GAL 018+00 275.93 -13.26 18.00 0.00 341.41 60.41 GPLANE 18 275.93 -13.26 GT 0236+610 40.14 61.22 333 07/05/94 PSR 1951+32 298.76 28.07 64.87 -0.03 69.89 50.97 CYG X-3 308.11 40.96 PSR 0611+22 93.56 22.42 334 07/12/94 GAL 006-04 273.86 -26.03 5.81 -4.30 238.09 58.96 GPLANE 15 274.47 -15.90 HER X-1 254.46 35.34 335 07/19/94 GAL 253-42 69.26 -47.25 253.40 -42.00 107.01 36.16 PSR J0437-47 69.26 -47.25 GEMINGA 98.48 17.77 336 08/01/94 GAL 083-45 345.81 8.87 83.09 -45.47 81.19 31.01 NGC 7469 345.81 8.87 NRAO 140 54.13 32.31 337 08/08/94 PKS 0528+134 87.70 0.98 205.00 -13.00 178.49 39.05 PSR 0656+14 104.70 14.23 NGC 4151 182.63 39.41 338 08/29/94 VELA PULSAR 128.92 -45.18 263.59 -2.74 200.60 17.34 VELA PULSAR 128.92 -45.18 3C 273 187.28 2.05 339 09/20/94 3C 317 234.71 -1.82 4.05 40.40 143.62 -30.89 PG 1416-129 214.77 -13.18 MCG -5-23-16 146.92 -30.96 10/04/94 end Phase 3 * Phase 2 target