Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 6056: 1994X; X-RAY N IN Sco; UZ Boo

The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).

Read IAUC 6055  SEARCH Read IAUC 6057

View IAUC 6056 in .dvi or .ps format.
IAUC number

                                                  Circular No. 6056
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)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

     R. H. McNaught, Anglo-Australian Observatory, reports his
discovery of an apparent supernova of mag 18.5 on an R plate taken by
M. Hartley with the U.K. Schmidt Telescope (UKST) on Aug. 15.  The
supernova is at R.A. = 0h15m20s.62, Decl. = -24o53'50".5 (equinox
2000.0) and is located in a spiral arm, 1".0 east and 16".4 south
of the galaxy's center.  The new object was confirmed on a CCD
image taken by McNaught and G. J. Garradd with the 1.0-m telescope
at Siding Spring on Aug. 16.  No image appeared at this location on
various UKST plates taken > 5 years ago.  A nearby star of mag 17.5
has position end figures 21s.70, 42".2.

     C. A. Wilson, B. A. Harmon, S. N. Zhang, W. S. Paciesas, G. J.
Fishman, M. Scott, B. C. Rubin, and R. B. Wilson report for the
Compton Gamma Ray Observatory BATSE Team:  "From an examination of
individual occultations of GRO J1655-40, we find that the initial
rise of the source intensity (about 10-90 percent) in the band 20-
100 keV was between July 27.75 and 28.25 UT.  The source was at the
0.85-Crab level from July 28.25 to about Aug. 8 and then decreased
to 0.66 Crab from Aug. 9 to 12 (band 20-100 keV; 10 percent
uncertainty), with significant daily variations.  Since Aug. 12, GRO
J1655-40 has dropped more rapidly:  0.3 (+/- 0.03) Crab on Aug. 13
and 0.15 (+/- 0.03) Crab on Aug. 14-15.  The spectrum extends to at
least 200 keV in the early part of the outburst, then to at least
400 keV after Aug. 6.  The spectrum softens during initial rise,
from -2.5 to about -3.0, and varies between -2.5 and -3.5 after
July 28, similar to black-hole candidate x-ray novae.  Power density
spectra inspected through Aug. 5 show no low-frequency noise
(10-500 mHz) in the hard x-ray region, which is unusual for such
objects.  Using data collected since Aug. 5, we obtain the following
improved location:  R.A. = 16h54m.6, Decl. = -39o54' (equinox
2000.0; 1-sigma error along the southeast-to-northwest direction is
0.2 deg and along southwest-northeast is 0.1 deg).  This location
is about 0.13 deg from the optical candidate reported by Bailyn et
al. (IAUC 6050)."

     This WZ-Sge-type variable may be in outburst for the first
time in 16 years.  Visual magnitude estimates:  Aug. 16.458 UT,
[15.1 (M. Iida, Nagano, Japan); 17.167, 13.9 (D. York, Abiquiu, NM).

1994 August 17                 (6056)            Daniel W. E. Green

Read IAUC 6055  SEARCH Read IAUC 6057

View IAUC 6056 in .dvi or .ps format.

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!