Compton Observatory Science Report #137
Thursday, September 30, 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.  

Correction:  The name of the latest Target of Opportunity source
that was observed from Sept 21 to Sept 22 was garbled in last week's
report.  The correct name is GRS 1009-45.

Science operations are continuing.  Operations to prepare for
next Monday's start of the reboost are underway, with a maneuver to
to reboost attitude scheduled for Friday, October 1.  It has been
decided that the spacecraft will not be re-oriented for observations
of the source GRO J1719-24 (see BATSE report below).

ARCHIVES
--------

Archive contents-
	BATSE   - Bursts to trigger 1466, flares to trigger 884, 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 1-13 are available
        Egret   - Periods 0.2-30 are available (Maps and photon lists)
        OSSE    - Periods 0.2-13 (minus pd 3) are available (SDB data).  
                  Pulsar data also available off-line.

BATSE
-----
The following has been submitted as an IAU Circular:

GRO J1719-24

B. A. Harmon, NASA/Marshall Space Flight Center, S. N. Zhang, Universities
Space Research Association, W. S. Paciesas, University of Alabama, Huntsville,
and G. J. Fishman, NASA/Marshall Space Flight Center, report for the Compton
Observatory/BATSE Team:  A new hard x-ray transient has been discovered using
Earth occultation monitoring on September 25 in the energy range 20-320 keV.
Its location is R.A. = 17h19.2m Dec.=-24d24m with 1-sigma error box with the
following corners R.A., Dec. = 17h24.4m, -26d12m; 17h17.6m, -24d30m; 17h11.2m,
-21d18m; 17h20m,-24d0m.  The spectrum is hard, with power law number index -2.0
in the 20-100 keV band; however, the broad-band spectrum is better fit with a
thermal bremsstrahlung model with temperature kT = 70-100 keV.  The temperature
decreases with increasing intensity. The light curve shows the source becoming
visible late on Sept 24, with the following average intensities relative to the
Crab (20-100 keV); +/- 20%): Sept 24: 0.07, Sept 25: 0.46, Sept 26: 0.82, 
Sept 27: 1.1, Sept 28: 1.2.  Fast intensity variations (~seconds) are
also observed. Monitoring of the source is continuing. 

During viewing period 303.4 and 303.5 BATSE folded-on-board pulsar data will be
collected for the Crab Pulsar, PSR 0525+21, PSR 1259-63, and PSR 0835-41. 
The pulsar hardware will also be used to collect 31 ms resolution single sweep
data for power spectral analyses of GRO J1719-24.

COMPTEL
------- 
The COMPTEL instrument is performing well and continues routine
observations. In anticipation of the orbital reboost of the GRO
spacecraft, scheduled to begin on Monday, the COMPTEL instrument will
be placed in a low-power mode on Friday, 1 October. COMPTEL will
remain "off" for the duration of the reboost maneuver.  

Among the scientific results presented by the collaboration last week
at the 2nd Compton Symposium in Maryland were exciting reports on diffuse
gamma-ray line emission observed by COMPTEL. Bloemen et al. reported the
detection of intense gamma-ray emission from the Orion complex in the
3-7 MeV range, which can be identified with the cosmic-ray induced 4.44
and 6.13 MeV nuclear de-excitation lines of carbon and oxygen. Iyudin et al.
presented the detection of line emission from the Cas A supernova remnant
at 1.15 MeV, originating from the decay of 44Ti. A status report on the
mapping of the 1.8 MeV radiation from 26Al in the Galactic plane by R. Diehl
showed increasing evidence for highly structured emission, including 
a particularly interesting excess in the Vela region. These findings
were generally considered to be a real breakthrough in gamma-ray line
spectroscopy.

The importance of COMPTEL observations of AGNs was illustrated by Blom et al.,
Collmar et al., and Maisack et al. Presentations by McConnell et al. and
van Dijk et al. showed COMPTEL's latest results on Galactic compact sources
(Cyg X-1, Nova Persei, and 2CG135). Hermsen et al. presented the preliminary
results of a GRO-wide monitoring of WR140 during its periastron passage.
The reviews by J. Ryan and A. Strong included the latest results of COMPTEL
observations of the Sun and the diffuse Galactic emission, respectively. 

EGRET
-----
EGRET operations were normal this week.  The current
observation period ends tomorrow and detailed preparations
have been made for the reboost period.  The generally low
value of short observations for EGRET has been noted
before.  This statement has certainly been true in Phase 2;
we hope they can be avoided in Phase 3.

Seth Digel, a Compton Observatory fellowship winner, has
now joined us to work on his project.  We continue to have a
healthy number of guest investigators visiting us.

OSSE
----
OSSE operations have returned to normal.  The cause of the two lock-ups
last week has been traced to a subtle bug in flight software we introduced
in a recent update.  We have removed the offending code and corrected the
software update.

For the brief pointing before the reboost interval, the Z-axis target is
Cyg X-1, and the X-axis target is 3C 273.  The Sun is near the OSSE scan
plane, so the slewing response to BATSE solar flare triggers is enabled.
There have been no slews since the last report.

For the reboost period, OSSE will be placed in a low-power mode each day
on which a boost occurs, then restored to safehold mode after operations
settle down.  On days on which there is no orbit boost, we plan a series
of science and engineering tests.

Data from viewing period 14 will be delivered today to the Compton GRO
Science Support Center Archive.  Targets during this period were the
Galactic Center region and Eta Car.

Other Items:
------------
For the interest of those working with Phase 2 data, the final Phase 2
Viewing Plan is attached.  The last observations of Phase 2 were completed 
on September 7.



8/5/93                      COMPTON PHASE 2 VIEWING PLAN AS OF AUGUST 5, 1993

                                             GRO Z-AXIS*
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
---------------------------------------------------------------------------------------------------------------------------------
201   11/17/92 HER X-1     253.15  42.26    66.79  39.28   266.02 -47.01 HER X-1       254.46  35.34 G PLANE 355  263.30   -33.17
202   11/24/92 HER X-1     251.55  45.40    70.85  40.50   270.04 -43.08 HER X-1       254.46  35.34 G CENTER     266.40   -28.94
203.0 12/01/92 CYGNUS      306.59  39.34    77.85   0.69   258.44 -39.15 CYG X-1       299.59  35.21 G CENTER     266.40   -28.94
203.3 12/08/92 CYGNUS      306.59  39.34    77.85   0.69   264.05 -41.96 CYG X-1       299.59  35.21 G CENTER     266.40   -28.94
203.6 12/15/92 CYGNUS      306.59  39.34    77.85   0.69   258.44 -39.15 CYG X-1       299.59  35.21 G CENTER     266.40   -28.94
204   12/22/92 3C 273      188.99  -0.74   294.70  61.88   279.50 -34.03 3C 273        187.28   2.05 G PLANE 355  263.30   -33.17
205   12/29/92 3C 273      188.84  -1.03   294.47  61.58   279.32 -24.79 3C 273        187.28   2.05 G PLANE 5    269.27   -24.64
206   01/05/93 3C 273      188.99  -0.74   294.70  61.88   279.50 -34.30 3C 273        187.28   2.05 G PLANE 355  263.30   -33.17
207   01/12/93 IC 4329A    203.86 -30.41   314.06  31.51   293.35   0.86 IC 4329A      207.33 -30.31 PSR 1822-09  276.25    -9.00
208   02/02/93 NGC 4507    198.47 -41.93   307.39  20.75   296.86  -9.24 NGC 4507      188.90 -39.91 NGC 6814     295.67   -10.31
209   02/09/93 2CG 010-31  305.69 -40.81     0.24 -34.01   297.95  48.93 2CG 010-31    304.75 -31.84 3C 390.3     280.56    79.76
210   02/22/93 GAL CENTER  257.65 -29.10   355.62   6.28   351.03  -6.03 1E 1740-2942  265.98 -29.72 MCG -2-58-22 346.18    -8.69
211   02/25/93 GAL 123-05   18.38  58.05   125.86  -4.70     8.08 -31.53 4U 0115+634    19.86  62.49 47 TUC         5.83   -72.07
212   03/09/93 WR 140      298.65  50.54    84.33  11.43   341.61 -31.07 WR 140        305.12  43.85 NGC 7314     338.94   -26.05
213   03/23/93 CRAB PULSAR  80.30  22.29   182.63  -8.22   348.47   4.44 CRAB PULSAR    83.52  22.02 MRK 509      311.04   -10.72
214   03/29/93 GAL CENTER  257.65 -29.10   355.62   6.28   351.03  -6.03 1E 1740-2942  265.98 -29.72 MCG -2-58-22 346.18    -8.69
215   04/01/93 CEN A       203.26 -39.28   311.66  22.89    53.56 -46.55 CEN A         201.37 -43.02 SN 1987A      83.86   -69.27
216   04/06/93 SN 1993J    143.64  71.46   140.75  38.11     3.37  14.47 SN 1993J      148.84  69.02 M31           10.68    41.27
217   04/12/93 CEN A       203.26 -39.28   311.66  22.89    53.56 -46.55 CEN A         201.37 -43.02 SN 1987A      83.86   -69.27
218   04/20/93 NGC 4151    180.75  43.09   151.41  71.26    31.04  42.71 SN 1993J      148.84  69.02 NGC 4151     182.64    39.41
219.1 05/04/93 REBOOST THRUSTER TESTING
219.4 05/05/93 GAL CENTER  245.35 -27.22   350.10  15.86   341.26 -11.31 1E 1740-2942  265.98 -29.72 MCG -2-58-22 346.18    -8.69
219.7 05/07/93 REBOOST CALIBRATION BURN
220   05/08/93 SMC          24.11 -72.07   298.09 -44.63    69.97  12.70 SMC X-1        19.18 -73.44 3C 120        68.30     5.35
221   05/13/93 CRAB PULSAR  85.21  19.46   187.52  -5.88   326.68  53.49 CRAB PULSAR    83.52  22.02 PSR 1951+32  298.24    32.89
222   05/24/93 NGC 4151    178.02  42.25   157.79  70.63    60.65  26.85 NGC 4151      182.64  39.41 MCG +8-11-11  88.73    46.44
223   05/31/93 GAL CENTER  265.98 -29.72   359.14  -0.09   316.33  48.19 1E 1740-2942  265.98 -29.72 CYG X-3      308.11    40.96
224   06/03/93 SMC          24.11 -72.07   298.09 -44.63    69.97  12.70 SMC X-1        19.18 -73.44 3C 120        68.30     5.35
225   06/15/93 REBOOST
226   06/19/93 GAL 355+05  258.44 -30.35   355.00   5.00   189.52  31.57 G CENTER      266.40 -28.94 COMA CLUSTER 194.90    27.96
227   06/28/93 SN 1993J    143.64  65.00   148.11  41.22   116.97 -22.62 SN 1993J      148.84  69.02 PSR 0740-28  115.71   -28.38
228   07/13/93 SN 1993J    145.33  63.18   149.85  42.69   131.74 -26.16 SN 1993J      148.84  69.02 VELA PULSAR  128.92   -45.18
230   07/27/93 VELA REGION 143.03 -54.64   276.66  -2.27   127.10  34.31 GRO J1008-57  145.00 -59.00 QSO 0716+714 110.48    71.34
230.5 07/30/93 VELA REGION 149.86 -53.17   278.79   1.44   131.53  35.41 GRO J1008-57  145.00 -59.00 QSO 0716+714 110.48    71.34
231   08/03/93 NGC 6814    289.94 -15.33    22.22 -13.08   186.93 -39.38 NGC 6814      295.67 -10.31 NGC 4507     188.90   -39.91
229   08/10/93 GAL 5+05    264.60 -22.06     5.00   5.00   188.59  30.82 G CENTER      266.40 -28.94 COMA CLUSTER 194.90    27.96
229.3 08/11/93 PERSEID METEOR SHOWER
229.5 08/12/93 GAL 5+05    264.60 -22.06     5.00   5.00   188.59  30.82 G CENTER      266.40 -28.94 COMA CLUSTER 194.90    27.96
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
      09/07/93   end Phase 2
 ** Phase 3 target
*  Z-axis is pointing direction for COMPTEL and EGRET.  OSSE points in X-Z plane.  RA and DEC are J2000.