Central Bureau for Astronomical Telegrams
IAUC 4653: (2060); GS 1826-24; GX 339-4
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Circular No. 4653
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
(2060) CHIRON
D. P. Cruikshank and W. K. Hartmann, observing with the NASA
Infrared Telescope Facility, and D. J. Tholen with the University of
Hawaii 2.24-m reflector, report that the anomalous brightening of
Chiron, first reported on IAUC 4554, has not only continued,
but has intensified. The VJHK absolute magnitudes on Sept. 5.6 UT
were about 1.05 mag brighter than the absolute magnitudes determined
from observations between 1981 and 1983. V is now 16.85. There has
been no obvious change in the colors, which remain neutral.
GS 1826-24
F. Makino and the Ginga Team telex: ''A new x-ray source, GS
1826-24, located at R.A. = 18h26m12s, Decl. = -23 58.8 (equinox 1950.0),
was discovered on Sept. 8 with the Large-Area Counters aboard the
Ginga satellite. The corners of the error box are R.A. = 18h27m31s,
Decl. = -24 00.6; 18h27m05s, -24 18.0; 18h24m48s, -23 57.6; 18h25m26s,
-23 39.0. The x-ray intensity was highly variable on timescales < 1 s;
the average intensity during Sept. 8-10 was 26 mCrab. The power-law-
type spectrum has photon index -1.67 +/- 0.02."
GX 339-4
K. Makishima, Department of Physics, University of Tokyo; S.
Miyamoto, Osaka University; and the Ginga Team report: ''We detected
strong quasi-periodic oscillations (QPO) of about 6 Hz in the x-ray
flux from the peculiar x-ray source GX 339-4 (4U 1658-48; Makishima
et al. 1986, Ap.J. 308, 635) during Ginga observations made on Sept.
3, 5, and 6. The x-ray intensity of 0.7-0.85 Crab (1-37 keV) and the
very soft spectrum indicate that the source was in its high state.
On Sept. 3, 5, and 6, respectively, the QPO centroid frequencies
were 6.51, 6.07, and 5.82 Hz; the QPO amplitudes (rms) were 2.7,
4.0, and 3.9 percent; and the QPO peaks were very narrow, with FWHM
frequencies of 0.9, 1.4, and 0.5 Hz. The second harmonic of the
QPO was visible on Sept. 5 and 6, with an rms amplitude of 2.3 and
0.8 percent, respectively. A red noise component exists in all the
power spectra; its rms amplitude integrated over 0.1-64 Hz was 6.6,
8.5, and 2.6 percent on Sept. 3, 5, and 6, respectively. The red
noise had about 1/f slope over 0.01-64 Hz on Sept. 6, while it
flattened below 2 Hz on Sept. 5."
1988 September 14 (4653) Daniel W. E. Green
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