Central Bureau for Astronomical Telegrams
IAUC 5900: X-RAY N IN Oph; GRS 1915+105
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Circular No. 5900
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
X-RAY NOVA IN OPHIUCHUS
B. A. Harmon and G. J. Fishman, Marshall Space Flight Center,
NASA; W. S. Paciesas, University of Alabama, Huntsville; and S. N.
Zhang, Universities Space Research Association, report for the
Compton Observatory BATSE Team: "The hard x-ray transient GRO
J1719-24 has been remarkable in its steady, persistent, high level
of emission. It reached a peak intensity of about 1.4 Crab (20-100
keV) five days after discovery (IAUC 5874) on Sept. 30. The 1/e
decay time is about 300 days from a fit of occultation data
obtained during Oct. 1-Nov. 22, although a linear fit to the light
curve is equally good, with intensity dropping at about 0.3 +/-
0.05 percent per day relative to the peak. This is believed to be
the slowest decay of any hard x-ray nova observed. Power-law fits
to the spectrum in the band 20-100 keV showed the spectrum softening
from -2.0 to -2.3 (+/- 0.05) during the rise, then softening
more gradually since the end of September; it continues to be the
brightest source in the sky in this energy range."
GRS 1915+105
L. F. Rodriguez, National Radio Astronomy Observatory and
Instituto de Astronomia, Universidad Nacional Autonoma de Mexico; and
I. F. Mirabel, Service d'Astrophysique, Centre d'Etudes de Saclay,
report: "Using the Very Large Array, we are observing a strong
burst in the radio counterpart of the hard x-ray transient in
Aquila; on Nov. 29, we detected GRS 1915+105 in a remarkably high
radio state. In our previous VLA observations of this source, it
usually exhibited time-variable centimeter continuum emission at
levels of a few mJy (IAUC 5773, 5830). Recent flux densities: Nov.
29, 90 mJy at 6 cm, 120 mJy at 3.5 cm, 130 mJy at 2 cm; Dec. 5, 300
mJy at 20 cm, 590 mJy at 6 cm, 450 mJy at 3.5 cm, 310 mJy at 2 cm,
190 mJy at 1.3 cm. The inverted spectrum observed on Nov. 29 is
suggestive of optically-thick synchrotron emission, while that of
Dec. 5 was indicative of optically-thin synchrotron emission for
wavelengths below 6 cm and with a possible self-absorption turnover
between 20 and 6 cm. It is of interest to obtain information at
other wavelengths during this radio outburst. The position of the
radio source is R.A. = 19h12m49s.97, Decl. = +10o51'26".8 (equinox
1950.0; accuracy about 1")."
1993 December 6 (5900) Daniel W. E. Green
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