Central Bureau for Astronomical Telegrams
IAUC 6340: GK Per; 29P
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Circular No. 6340
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)
GK PERSEI
M. Ishida, A. Yamashita, H. Ozawa, F. Nagase, and H. Inoue,
Institute of Space and Astronautical Science, communicate on behalf
of the ASCA team: "ASCA observed GK Per in outburst during Mar.
4.33-4.87 UT in the energy band 0.5-10 keV, during the period that
the optical magnitude was in the range V = 11.8-12.1. The mean
counting rates of the SIS and GIS sensors were 1.1 and 1.3 counts/s,
respectively. Sinusoidal intensity modulation is clearly seen with
a period of 351 s, and the amplitude of the sinusoid is about 30
percent in the band 0.7-10 keV. A periodic intensity variation
with a typical time scale of several thousands of seconds is also
observed. The phase-averaged spectra of both the SIS and GIS are
well represented by a thermal bremsstrahlung continuum with a
temperature 18 (+6/-4) keV, plus a fluorescent iron emission line
centered at 6.40 +/- 0.02 keV with an equivalent width of 100 +/-
30 eV. No evidence of thermal plasma emission lines is obtained.
Both of the spectra show a heavy absorption feature that can be
approximated by the sum of three components of different
absorptions with hydrogen column densities of 50, 6, and 1 x 10E22
cmE-2. The covering fractions of the three components over the x-
ray emission region are 75, 24, and 1 percent, respectively. The
x-ray flux at 2-10 keV is 1.9 x 10E-10 erg cmE-2 sE-1,
corresponding to 10 mCrab; assuming a distance of 525 pc to GK Per,
we obtain an x-ray luminosity of 6 x 10E33 erg/s in this energy
range. Correcting for the absorption, the bolometric luminosity is
estimated to be as large as 3 x 10E34 erg/s."
COMET 29P/SCHWASSMANN-WACHMANN 1
H. Boehnhardt and C. Ries, University of Munich; and S.
Peschke, Max-Planck-Institut fur Kernphysik, Heidelberg, write: "We
performed V and R CCD imaging of comet 29P on Mar. 8-9 with the
0.80-m Mt. Wendelstein telescope of the University of Munich
Observatory. The comet showed a large coma of slightly elliptical
shape (north-south diameter > 2'.2 = 500~000 km; east-west diameter
> 1'.7 = 390~000 km) with a bright central condensation. A strong
jet spanning an angle of about 30-40 deg was present toward p.a. 45
deg from the nucleus. The jet curved northward and ended in a
cloudy structure about 1' from the central peak in coma brightness,
at p.a. 350 deg. Some fainter structures were detected in the coma
in the southwest quadrant and toward the east. The observed
features did not show day-to-day variability (to the level of our
on-line analysis)."
(C) Copyright 1996 CBAT
1996 March 9 (6340) Daniel W. E. Green
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