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IAUC 6348: GRS 1739-278; PKS 0208-512; C/1995 O1

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                                                  Circular No. 6348
Central Bureau for Astronomical Telegrams
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)
Phone 617-495-7244/7440/7444 (for emergency use only)

GRS 1739-278
     J. Paul, L. Bouchet, E. Churazov, and R. Sunyaev, on behalf of
the SIGMA/Granat team (Service d'Astrophysique du CEA, Saclay;
Centre d'Etude Spatiale des Rayonnements, Toulouse; Space Research
Institute, Moscow), communicate:  "During an observation of the
galactic-center region started on Mar. 18 (effective duration
86 000 s), the SIGMA telescope onboard Granat detected a new hard
x-ray source at the most probable position R.A. = 17h39m28s, Decl.
= -27o45'.6 (equinox 1950.0; uncertainty +/- 3').  Because of some
ambiguity inherent to coded-mask telescope imaging, the source
position could also be at R.A. = 17h38m07s, Decl. = -34o24'.0 (+/-
3').  Preliminary estimates of the flux level give 80 +/- 28 mCrab
in the range 40-75 keV, 51 +/- 20 mCrab over 75-150 keV, and 104
+/- 50 mCrab over 150-300 keV.  A 5.5-sigma excess was detected at
the same positions in the lower energy band during the previous
observation (started on Mar. 16.77 UT), showing that the source was
already active and probably brighter.  Because of the hard spectrum,
the source could be a new blackhole x-ray nova, and observations at
other frequencies are urged.  Further SIGMA observations should
clarify position ambiguity."

PKS 0208-512
     W. T. Vestrand and J. G. Stacy, University of New Hampshire;
and R. Mukherjee and P. Sreekumar, Goddard Space Flight Center,
NASA, report:  "Quick-look analysis of data taken during Mar. 5-16
by the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the
Compton Gamma Ray Observatory indicates that PKS 0208-512 is
currently in a high-intensity state.  The current integral flux
above 100 MeV is > 10E-6 photon cmE-2 sE-1 and is comparable to or
exceeds the highest gamma-ray flux ever seen from this variable
gamma-ray blazar.  While quick-look data are not yet available for
flux estimates at MeV energies, PKS 0208-512 has been proposed as a
prototype for a class of 'MeV blazars' that exhibit highly variable
emission at MeV energies.  Multi-wavelength observations are
essential for modeling this potential new class of objects, and we
encourage southern-hemisphere observers to observe PKS 0208-512
while in outburst."

     Visual m1 estimates by R. Keen, Mt. Thorodin, CO:  Feb. 24.52
UT, 8.6 (0.15-m reflector); Mar. 15.50, 8.5; 20.50, 8.6 (0.32-m

                      (C) Copyright 1996 CBAT
1996 March 22                  (6348)            Daniel W. E. Green

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