Central Bureau for Astronomical Telegrams
IAUC 3292: 4U 1630-47; Cyg X-2; IMPORTANT NOTICE
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Read IAUC 3293
Circular No. 3292
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
4U 1630-47
S. Holt, L. Kaluzienski, R. Mushotzky, F. Boldt and P.
Serlemitsos, Goddard Space Flight Center, report that recent observations
of the galactic plane in Norma with the Ariel 5 all-sky
monitor reveal the presence of a bright source at a position consistent
with that of the recurrert transient x-ray source 4U 1630-47.
The 3-6-keV flux measured on Oct. 8 (shortly after the
source entered the field of view of the detector) was approximately
one-third that of the Crab Nebula (assuming an intensity
for the nearby bright variable source 4U 1642-45 equal to the observed
Uhuru maximum). Quick-look data obtained with the HEAO-A2
experiment on Sept. 6 also show a source at approximately this intensity
roughly consistent with the position of 4U 1630-47. The
latest outburst from this source was observed in 1977 Nov. (IAUC
3144), with subsequent detections reported in 1978 Mar. (IAUC 3197)
and June (IAUC 3227). This, if the identification of the above
source with 4U 1630-47 is correct, the present observations are indicative
of a prolonged emission plateau or extended secondary
maximum in the decay of this object. In either case, this would
represent the longest-lived flaring episode of a 'transient'
source yet observed.
CYGNUS X-2
D. Crampton and A. Cowley, Dominion Astrophysical Observatory,
write: "New spectroscopic observations of Cyg X-2 show the orbital
period to be 9.8 days. A phase-dependent spectral-type variation
(A5-F2) implies strong x-ray heating on the optical star. It is
expected that a corresponding photometric variation of up to a few
tenths of a magnitude should be present. Superior conjunction
occurs at: JD 2443161 + 9.8431 E."
IMPORTANT NOTICE
It seems that the preaddressed cards for some recent Circulars
have been mixed up, with the result that subscribers have received
two copies of some issues and none of others. The problem was particularly
acute with IAUC 3281-3283 and 3285-3286, and we are still
trying to assess the situation. It would be helpful if subscribers
writing for missing issues would enclose any duplicate issues they
might have received.
1978 October 18 (3292) Brian G. Marsden
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