Central Bureau for Astronomical Telegrams
IAUC 3006: HARD X-RAY BURSTS; VV Cep; U Aqr
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Circular No. 3006
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK Telex: 921428
Telephone: (617) 864-5758
HARD X-RAY BURSTS
W. Mayer, Massachusetts Institute of Technology, reports that
the SAS-3 Observatory has detected eleven events, most likely produced
by extremely intense recurrent bursts of hard x-rays. The
bursts were detected on Oct. 22d19h36m11s, Nov. 6d03h25m31s,
6d04h14m33s, 6d15h12m26s, 7d08h31m15s, 8d13h37m18s, 9d03h47m32s,
9d19h35m00s, 10d07h22m30s, 10d14h28m08s and 10d14h31m38s UT. Each
event produced simultaneous signals in several detectors whose
fields of view do not overlap. The bursts must therefore have been
of sufficient intensity and penetration to register through the
sides of the detectors; it is estimated that the incident flux of
energy in each burst exceeded 10**-6 erg cm**-2. Bursts of this kind
have not been observed before by SAS 3, and it therefore seems very
likely that the burst activity started only recently. Positional
analysis based on earth blockage places the source within the ~ 35o
right-ascension interval from R.A = 22h20m to 0h40m or within ~ 25o
of the celestial poles. Observations from other satellites of
these and possible future bursts from this source would be most
helpful in reducing the positional uncertainty.
VV CEPHEI
C. A. Whitney, Harvard College Observatory, reports the following
observations, obtained with the 40-cm reflector at the Agassiz
Station: Nov. 9.1 UT, V = 5.03, B = 6.97, U 8.05; Nov. 11.1 UT, V
= 5.09, B = 7.02, U = 8.14. The U magnitude is 0.9 fainter than
its normal value (Lee 1970, Astrophys. J. 162, 217), suggesting
that the first contact of the eclipse of the B-type main-sequence
component by its M-type supergiant companion has already occurred
(cf. IAUC 2811; Fredrick 1960, Astron. J. 65, 628). G. G. Spear,
Sonoma State College Observatory, writes that second contact is
predicted for Dec. 1, while mid-eclipse is expected sometime in Aug.
1977; the eclipse depth is expected to be perhaps 0.25 magnitude in
V, 0.65 magnitude in B and nearly 2.0 magnitudes in U. A. Galatola
has organized a campaign to observe the eclipse and would be glad
to receive observations (especially those in the UBV system); his
address is 47 Galbraith Avenue, West Norriton, PA 19401, U.S.A.
U AQUARII
Visual magnitude estimates (cf. IAUC 2995) by J. Bortle, Brooks
Observatory: Oct. 12.1 UT, 14.0; 15.1, 14.2; 27.0, [14.5; 28.0, 14.3.
1976 November 12 (3006) Brian G. Marsden
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