Central Bureau for Astronomical Telegrams

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IAUC 6087: 1994Z; X-RAY N IN Sco

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                                                  Circular No. 6087
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     TWX 710-320-6842 ASTROGRAM CAM

     A. Wassilieff, Palmerston North, New Zealand, reports his
CCD discovery of a supernova on Oct. 2.51 UT, about 36" east and 12" south
of the nucleus of NGC 87.  The object was estimated at mag 14.6 and
noted again on Oct. 3.38, and it was not present on a similar image
obtained on 1992 Nov. 29.  Measurements by G. V. Williams of the
faxed image (scale 7".5/mm) yield the position R.A. = 0h18m49s.49, Decl.
= -48d54'28".0 (equinox 1950.0).  End figures for the galaxy nucleus are
47s.16, 20".3.

     M. M. Phillips, Cerro Tololo Interamerican Observatory, reports that
CCD images obtained by J. Maza and X. Gomez on Oct. 4 confirm the presence
of an apparent supernova in NGC 87.  Conditions were not photometric,
but a comparison with a sequence around T Phe gave V about 16, B-V
about +0.1.

     S. Benetti, European Southern Observatory (ESO) and G. Hasinger,
Astrophysikalisches Institut, Potsdam, report that inspection of a
fully-reduced CCD spectrum (range 450-700 nm, resolution 1.1 nm)
obtained on Oct. 4.12 UT with ESO 2.2-m telescope + EFOSC2 confirms that
the object is a type II supernova 2-3 weeks after outburst.  Strong H beta
and H alpha lines with P-Cyg profiles are superimposed on a blue
continuum.  The He I 587.6-nm line is also present with a P-Cyg profile.
The expansion velocity deduced from the minima of the H beta and He I
587.6-nm lines is about 10 000 km/s.  A velocity of 12 000 km/s is
deduced from the H alpha minimum.

     N. Alexandrovich, K. Borozdin, V. Efremov and R. Sunyaev, Space
Research Institute, Moscow, on behalf of the MIR-KVANT team, report:
"According to data from the TTM telescope onboard the MIR space station
this x-ray nova is in a high (soft) spectral state typical of
black-hole candidates and similar to that observed recently in the
superluminous radio source GRS 1915-105 (IAUC 6080).  The flux detected
at 5 keV was 500 mCrab on Sept. 24 and 600 mCrab on Sept. 25.
The source spectrum within the 2-15-keV band can be approximated by a
blackbody fit with kT = 1.06 +/- 0.02 keV.  According to MIR-KVANT-HEXE
data, the 3-sigma upper limit to the tail of the hard flux is 5 and 15 mCrab
in the 15-45-keV and the 45-105-keV data, respectively.  In hard x-rays
the source is much weaker than 4U 1700-37 (50 mCrab in 15-45-keV band),
which is separated from the Sco x-ray nova by less than three degrees."

1994 October 4                 (6087)              Brian G. Marsden

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