Central Bureau for Astronomical Telegrams
IAUC 3688: GX 301-2 = 4U 1223-62; P/HALLEY; PLUTO APPULSE ON 1982 Apr. 15
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 3689
Circular No. 3688
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 617-864-5758
GX 301-2 = 4U 1223-62
M. Oda and the Hakucho Team report the detection of an x-ray
flaring of the x-ray pulsar GX 301-2. The x-ray intensity of this
source became above detection limit on Apr. 5 and reached the
maximum on Apr. 7. The peak intensity was 90 millicrab in 1-9 keV and
550 millicrab in 9-22 keV on Apr. 7. The apparent pulse period is
estimated to be 703s.8 +/- 0s.2 by a standard folding method from the
data of Apr. 5-8. The time of the flare center is in agreement
with the orbital ephemeris given by Watson, Warwick and Corbet
(1982, M.N. to be published), which predicts the next flare center
as l982 May 19.4 +/- 1.0 UT.
PERIODIC COMET HALLEY
D. C. Jewitt, G. E. Danielson and R. J. Terrile, California
Institute of Technology, write that an unsuccessful search for this
comet was made on 1981 Dec. 18.3 UT using the 5.l-m telescope. The
Space Telescope Wide Field Planetary Camera Investigation Definition
Team charge-coupled device was placed at the prime focus. The
seeing was measured to be 1" (fwhm). Twenty-four exposures of 3s00s
and twelve of 100s duration were obtained through a broadband filter
centered at 0.65 um; individual reduced 300 frames reach [r] =
24. Five summed frames, comprisinq five frames each, reach [r] >~
25. The probability that the image of the comet may be hidden by
overlapping images of brighter field stars is presumably much less
than 0.01. The 340" field of view is much larger than the
estimated positional errors (10" to 20" at most) in the predicted
ephemeris by D. K. Yeomans, Jet Propulsion Laboratory. The product
of geometric albedo and physical cross-section of the comet's nucleus
is presumably therefore less than 3 km; if the albedo is 0.5
at 0.65 um (comparable to Saturn's satellites), the radius is less
than 1.4 km. The undersigned has maintained for some years that B
>= 26 and has not anticipated success with searches before late 1983.
PLUTO APPULSE ON 1982 APRIL 15
Further analysis by M. P. Candy and others suggested that an
occultation by Pluto (cf. IAUC 3674) was unlikely, but that South
America and southern Africa would be closest to the track.
Monitoring by S. O'Meara and others at the Harvard College Observatory
during Apr. 15.052-15.073 UT showed no occultation.
1982 April 16 (3688) Brian G. Marsden
Read IAUC 3689
Our Web policy. Index to the CBAT/MPC/ICQ pages.
