Central Bureau for Astronomical Telegrams
IAUC 3235: X-RAY PULSATIONS FROM SS Cyg; N Ser 1978; Aql X-1
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Circular No. 3235
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
X-RAY PULSATIONS FROM SS CYGNI
F. Cordova, G. Garmire and I. Tuohy, California Institute of
Technology, report the discovery of x-ray pulsations from the dwarf
nova SS Cyg during optical outburst. The observations were carried
out using the HEAO-A2 low-energy detector during a 6-hr pointing
that commenced on June 14d19h00m UT. The x-ray data were found to
be strongly modulated with an average period of 8.9 s and a pulsed
fraction as high as 50 percent. The flux from the source was
0.07 photon cm**-2 s**-1 in the energy range 0.2 to 0.4 keV. At the
time of the x-ray measurement SS Cyg was undergoing an extended
optical outburst that began on June 8. J. Mattei, AAVSO, reports
that J. Morgan, Prescott, AZ, observed the star at visual magnitude
8.2 on June 14.24 UT and again on June 15.21 UT.
NOVA SERPENTIS 1978
R. D. Gehrz, G. Grasdalen, J. A. Hackwell, D. McClain, S. F.
McLaughlin and C. Sneden, University of Wyoming, report the following
magnitudes, obtained with the 229-cm Wyoming infrared telescope
on June 12 UT: 2.3 um, 6.24; 3.6 um, 3.35; 4.9 um, 2.04; 8.7 um, 0.66;
10.0 um, 0.56; 11.4 um, 0.36; 12.6 um, 0.32; 19.5 um, -0.27. Preliminary
reduction of observations extending through June 22 indicates
no substantial change. Johnson and Kron system observations on
June 16 UT gave V = 14.58 +/- 0.08, B-V = +1.31 +/- 0.04, V-R = +1.23
+/- 0.08.
AQUILA X-1
P. Charles, University of California at Berkeley; S. S. Holt,
Goddard Space Flight Center; and P. Sanford, University College,
London, report that the highly variable source Aql X-1 has recently
gone into outburst. Observations with the Ariel 5 all-sky monitor
revealed a source consistent with the position of Aql X-1 that
first exceeded 0.1 the intensity of the Crab Nebula on June 15,
reached 0.5 the intensity of the Crab by June 18 and was comparable
to the Crab (in the 3-6-keV energy band) by June 22. The Mullard
Space Science Laboratory's 3-9-keV detector on OAO Copernicus confirmed
this result with approximate intensities of 0.02 Crab on
June 14 and 0.40 Crab on June 18. This is the first x-ray outburst
for two years, and optical observations of Thorstensen et al's
(1978, Astrophys. J. 220, L131) counterpart are urged.
1978 June 27 (3235) Brian G. Marsden
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