Central Bureau for Astronomical Telegrams
IAUC 4839: TRANSIENT X-RAY BURSTER KS 1731-260; N Sco 1989; 1987A
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Circular No. 4839
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
TRANSIENT X-RAY BURSTER KS 1731-260
R. Sunyaev and the Kvant Team report: "During observations of the GX
1+4 field on Aug. 16 the TTM instrument of the Mir-Kvant X-ray
Observatory discovered a new transient x-ray burster at R.A. = 17h31m.1,
Decl. = -26d03' (equinox 1950.0; uncertainty 1'). The persistent flux
from this source in the 2-27-keV band varies from 50 to 90 mCrab, and a
bremsstrahlung fit to the spectrum corresponds to temperature kT = 5
keV. During subsequent observations on Aug. 20-21 the source was also
bright. Several outbursts of duration less than 15 s and averaged peak
flux up to 0.6 Crab were detected during Aug. 16-21. Further analysis
has revealed this source in a lower state during observations of the
galactic center region on 1988 Oct. 21, the 2-27-keV flux then being 25
mCrab."
NOVA SCORPII 1989
R. H. McNaught, Siding Spring Observatory, has measured a possible
candidate for the prenova of mag 20 on a survey plate (1974 June 20)
at R.A. = 17h48m34s.00, Decl. = -32d31'15".2 (equinox 1950.0). The
star shows no pronounced color, but on J films there appears to be an
elongation to the southwest, suggesting a blue star of mag around 21.
Other nearby stars have end figures 33s.68, 18".6 (mag 17) and 34s.04,
18".8 (mag 22), neither showing pronounced color. He adds that the
Aug. 10.38 UT prediscovery observation reported on IAUC 4838 should be
deleted and communicates the following visual magnitude estimates by A.
Pearce, Scarborough, Western Australia: Aug. 20.54 UT, 11.0; 21.54, 11.3;
22.51, 11.8.
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
P. Bouchet, A. van Dijsseldonk, R. Vela and F. Labrana report the
following infrared photometry, obtained during Aug. 14.40-14.45 UT at
the European Southern Observatory with the 3.60-m telescope and f/35
wobbling secondary mirror: J (1.24 microns) = 12.19 +/- 0.05; H (1.63
microns) = 12.08 +/- 0.04; K (2.19 microns) = 12.44 +/- 0.04; L (3.79
microns) = 10.79 +/- 0.21; M (4.64 microns) = 9.23 +/- 0.34; N1 (8.38
microns) = 6.42 +/- 0.34; N2 (9.69 microns) = 5.54 +/- 0.11; N3 (12.89
microns) = 3.64 +/- 0.18; Q0 (18.56 microns) = 1.31 +/- 0.13. They add:
"These results show that the slopes of the infrared lightcurves have not
changed significantly since day 640 after outburst (i.e. the decrease in
magnitude between day 640 and 903 is linear in all passbands)."
1989 August 24 (4839) Brian G. Marsden
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