Central Bureau for Astronomical Telegrams
IAUC 6266: GRS 1915+105; 4U 0115+634
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Circular No. 6266
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
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)
Phone 617-495-7244/7440/7444 (for emergency use only)
GRS 1915+105
B. A. Harmon, W. S. Paciesas, S. N. Zhang and K. J. Deal,
NASA/Marshall Space Flight Center, report, for the Compton
Observatory BATSE Team: "Hard x-ray flux (20-100 keV) from GRS
1915+105 has increased over the past month to a level comparable
to the intense outbursts seen in 1992 and 1994 (IAUC 5590, 5959).
The flux reached 300 mCrab around Oct. 15 and has remained near
this level (within 50 percent) as of Nov. 20. Less intense
outbursts reaching about 200 mCrab have also been observed since
June 1995. These are nonperiodic but are of similar intensity
and each about 15-20 days in duration. The source continues to
be variable on a daily basis. The hard x-ray activity correlates
well on long timescales (days to weeks) with the radio flux, but no
strong signature is seen in x-rays that corresponds to the shorter-
timescale (hours to days) radio flares reported below."
E. B. Waltman and R. S. Foster, Naval Research Laboratory; F. D.
Ghigo, National Radio Astronomy Observatory; and M. Tavani,
Columbia University, report: "The source GRS 1915+105 has been
active at 2.25 and 8.3 GHz during the time period Oct. 10-Nov. 20
as monitored by the Green Bank Interferometer. Radio flares as
large as 200-400 mJy (2.25 GHz) have been observed four times.
Flux densities between these flares ranged from 10 to 100 mJy,
compared to a quiescent level of 10 mJy or less prior to the
activity that began on Aug. 10 (IAUC 6204)."
4U 0115+634
M. H. Finger, M. Scott and K. Hagedon, Universities Space Research
Association; R. B. Wilson and C. A. Wilson, NASA/Marshall Space Flight
Center; M. Stollberg and W. S. Paciesas, University of Alabama,
Huntsville; and T. A. Prince and B. Vaughan, California Institute of
Technology, report for the BATSE/Compton GRO Observatory pulsar team:
"Pulsed hard x-ray flux is currently being detected from the transient
x-ray pulsar 4U 0115+634. The source was detected on Nov. 18, when
the rms pulsed flux (20-50 keV) was approximately 15 mCrab. This is
the first detection by BATSE of this source since the outburst that
occurred during 1994 May 8-June 27 (IAUC 5990, 5999). On 1995 Nov. 21
the rms pulsed flux (20-50 keV) was approximately 70 mCrab. The pulse
frequencies observed from Nov. 19 to 21 are consistent with a neutron-
star spin rate of 0.2766635 +/- 0.0000003 Hz at epoch JD 2450042 and a
spin-up rate of 1.4 +/- 0.3 x 10E-11 Hz/s, using the binary orbital
ephemeris of Cominsky et al. (1994, 2nd Compton Symposium, AIP Proc.
304, 294)."
1995 November 22 (6266) Brian G. Marsden
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