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IAUC 5587: GRO J0422+32 = GRS 0417+335; 1992ap; N Cyg 1992

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                                                  Circular No. 5587
Central Bureau for Astronomical Telegrams
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)
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GRO J0422+32 = GRS 0417+335
     A. J. Castro-Tirado, S. Brandt, and N. Lund, Granat WATCH team
(Danish Space Research Institute, Lyngby; and Space Research
Institute, Moscow), report:  "The hard x-ray transient reported by
Paciesas et al. on IAUC 5580 has been observed by the WATCH all-sky
monitor on Granat.  The source intensity above 20 keV was 2.5 Crab
on Aug. 11.7 UT.  The source has been localized to the following
position:  R.A. = 4h17m.5, Decl. = +33 30' (equinox 1950.0), with a
probable error radius of 0.5 deg."
     R. A. Cameron, Universities Space Research Association; and J.
E. Grove, R. A. Kroeger, W. N. Johnson, and J. D. Kurfess, Naval
Research Laboratory; on behalf of the Compton Observatory OSSE team,
report:  "Preliminary analysis of the spectrum of the gamma-ray
transient source GRO J0422+32 (IAUC 5580, 5584), derived from OSSE
observations between Aug. 11.10 and 12.00 UT, shows the source to
have a spectrum similar to, and three times brighter than, the
black-hole candidate Cygnus X-1 as observed by OSSE in 1991 June.
Significant emission is observed up to about 600 keV, with an average
source flux of 1.8 photons cmE-2 sE-1 MeVE-1 at 100 keV.  The
continuum spectrum between 60 and 600 keV is not compatible with a
single power law.  The spectrum over this energy range is well
represented by a two-temperature Sunyaev-Titarchuk comptonized plasma
emission model (Sunyaev and Titarchuk 1980, A.Ap. 86, 121), with
characteristic electron temperatures of 30 and 60 keV.  The
intensities of these two components are comparable at 100 keV and have
optical depths of about 6 and 3, respectively.  The OSSE instrument
is also collecting event rate data in 8-ms samples on GRO J0422+32.
Preliminary analysis of this timing data has shown no evidence for
QPO behavior."

SUPERNOVA 1992ap IN UGC 10430
     C. Pollas, Observatoire de la Cote d'Azur, reports the following
R magnitude estimates from OCA 0.9-m Schmidt telescope plates
taken by D. Albanese and Pollas:  July 6.97 UT, 17.2 (pre-discovery
plate); Aug. 8.88, 17.5; 10.89, 17.5.

     Selected visual magnitude estimates:  Aug. 4.83 UT, 8.9 (H.
Dahle, Khania, Crete, Greece); 8.96, 8.8 (B. H. Granslo,
Fjellhamar, Norway); 11.80, 9.3 (A. Boattini, Montelupo, Italy).

1992 August 14                 (5587)            Daniel W. E. Green

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