Central Bureau for Astronomical Telegrams
IAUC 6651: GRS 1915+105; 1997bp
The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).
Read IAUC 6652
.dvi or
.ps format.
Circular No. 6651
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)
GRS 1915+105
C. R. Robinson, S. N. Zhang, and M. L. McCollough,
Universities Space Research Association (USRA) and Marshall Space
Flight Center (MSFC); B. A. Harmon, MSFC, NASA; S. Dieters and W. S.
Paciesas, University of Alabama at Huntsville; M. Tavani, Columbia
University and IFCTR, Milan; R. P. Fender, Sussex University; G. G.
Pooley, Cambridge University; E. Waltman, Naval Research Laboratory;
I. F. Mirabel, Service d'Astrophysique, Centre d'Etudes de Saclay;
R. M. Hjellming, M. Rupen, and F. Ghigo, National Radio Astronomy
Observatory; L. F. Rodriguez, Universidad Nacional Autonoma de
Mexico; and K. Ebisawa, USRA and Goddard Space Flight Center,
report: "Following recent flaring activity at 2.25 and 8.3 GHz
observed by the Green Bank Interferometer, and hard-x-ray activity
observed by the Compton Gamma Ray Observatory (+ BATSE), we
observed the superluminal jet source GRS 1915+105 during May 7.90-
8.03 UT with the RXTE/PCA. Four repeating outburst cycles, of
period near 2000 s, were observed from the source. The gross
structure of the light curve can be described as a high-intensity
spike, reaching a height of 3200 counts/s, followed by lower-
intensity oscillations, a dip to a minimum level, and finally a
gradual recovery after which the entire cycle repeats. The
hardness ratio (defined above and below 11 keV) is inversely
correlated with intensity. BATSE monitoring of GRS 1915+105 before
and during these observations indicates a persistent hard component
with intensity 0.10-0.13 photon cmE-2 sE-1 in the band 20-100 keV.
Preliminary analysis of data since mid-April indicates that the
energy spectrum can be adequately fit with a power law of photon
index about -3. The day-to-day variability of the source increases
roughly in conjunction with the first GBI flare on April 25-26.
Additional RXTE observations and a coordinated infrared/VLA/VLBA
observation is scheduled for May 15.54-15.67. A light curve from
part of our RXTE observations, future observing plans, and
additional information on galactic superluminal sources will be
available from the WWW site at http://www.batse.msfc.nasa.gov/
multiwave. Interested observers are encouraged to visit this site
and to send information on their observations to multiwave@bbking.
msfc.nasa.gov."
SUPERNOVA 1997bp IN NGC 4680
Unfiltered CCD magnitude estimate by S. Moretti and S.
Tomaselli, Forli, Italy: May 2.94 UT, 15.2 (GSC comparison stars).
(C) Copyright 1997 CBAT
1997 May 9 (6651) Daniel W. E. Green
Read IAUC 6652
.dvi or
.ps format.
Our Web policy. Index to the CBAT/MPC/ICQ pages.
