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IAUC 2859: SN IN NGC 7723; X-RAY FLARE IN Nor; beta Per; theta1 Ori A; Cyg X-2; R CrB; N Per 1974

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                                                  Circular No. 2859
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.

     D. Ya. Martynov, Sternberg Astronomical Institute, reports
that this supernova (cf. IAUC 2858) was independently discovered by
V. A. Lipovetskij on a plate taken at the Byurakan Observatory on
Oct. 27.  The magnitude was 14.5.

     L. J. Kaluzienski, S. S. Holt, E. A. Boldt and P. J.
Serlemitsos, Goddard Space Flight Center, report the detection of
an x-ray flare in Norma with the Ariel 5 all-sky monitor.  The best
position is R.A. = 16h09m, Decl. = -52o.6 with an error circle of
approximately 2o radius.  The sources 3U 1702-36, 1636-53 and 1642-45
were simultaneously measured to within 1o of their known positions.  The
new source was half as bright as the Crab between Nov. 1 and Nov. 4.

     A. Epstein, Center for Astrophysics, Harvard and Smithsonian
Observatories, reports that the SAS-3 Group has observed an x-ray
source coincident with the position of beta Per (Algol).  The source
was observed with the rotating modulation collimator experiment for
a period of 3.2 x 10**4 s from Oct. 22.3 to 27.3 UT.  A 12-sigma signal
was observed, and the position has a 90-percent confidence error
radius of 1' centered on the star.  The intensity in the 1.7 to 6
keV range is approximately 1 count s**-1, which is equivalent to
about 10**31 erg s**-1 for a source at 30 pc.  This result is consistent
with the upper limit reported previously (Canizares et al.
1973, Astrophys. J. 183, L91).  There is some evidence for
intensity variation during the observation period.

theta1 ORIONIS A
     W. A. Feibelman, Goddard Space Flight Center, writes: "Following
the announcement by Lohsen (1975, IAU Inform. Bull. Variable
Stars No. 998) that the star theta1 Ori A is an eclipsing variable with
a period of 196.25 days, some 60 Allegheny Observatory plates of
the Trapezium region taken between 1963 and 1969 were searched for
variability.  On three nights (1966 Jan. 3-4 and 4-5, 1967 Jan. 30-31)
theta1 Ori A was considerably fainter than theta1 Ori D.  These minima
fall about 10 days behind the midpoint of the period, which was
confirmed to be 196.298 days by Strand (1975, IAU Inform. Bull. Variable
Stars No. 1025).  The present data strongly suggest a displaced,
broader, secondary minimum of an eccentric orbit for theta1 Ori A.
The next primary minimum is expected on 1975 Dec. 5 and should
last about 24 hours, according to Lohsen and Strand, but the next
secondary minimum should occur near 1976 Mar. 20 and be observable
for at least 48 hours.  Observations, including those of radial
velocity, are urged for a duration of about one week beginning at
the end of Nov. 1975 and again in the middle of March 1976."

     C. Chevalier, Observatoire de Meudon; S. A. Ilovaisky, Observatoire
de Meudon and Centre d'Etudes Nucleaires de Saclay; and G.
Branduardi and P. W. Sanford, Mullard Space Science Laboratory,
report: "Analysis of photoelectric photometry of the optical candidate
for Cyg X-2 (R.A. = 21h42m36s.91, Decl. = +38o05'27".9, equinox 1950.0;
Giacconi et al. 1957, Astrophys. J. 148, L129) obtained at the
Haute Provence Observatory and of x-ray observations of this source
made with the Copernicus satellite in 1974 and 1975 indicates that
the available data are consistent with a period of 13.6 days.  The
optical light curve, which shows intrinsic scatter, exhibits two
maxima and two minima per period and has an amplitude of 0.4 magnitude
in the B filter.  The 1974 x-ray light curve, whose amplitude
is of a factor of two, shows a minimum which coincides in phase
with one of the optical minima.  The 1975 x-ray curve, based on 12
days of observations in June, shows a smooth 45-percent flux modulation
with an intensity maximum at midphase (phi = 0.5).  Superposed
on this are sharp x-ray 'dips' during which the source drops in
intensity by as much as a factor of two.  The mean optical brightness
of Cyg X-2 in the B filter decreased from 1974 to 1975 by 0.3 magnitude,
whereas the mean x-ray level increased by about 50 percent.
Further correlated observations are in progress.

     Selected visual magnitude estimates: Oct. 24.0 UT, 7.9 (J. E.
Bortle, Brooks Observatory); 25.0, 8.0 (Bortle); 27.97, 9.3 (A. C.
Porter, Narragansett, Rhode Island); 28.0, 8.9 (Bortle); 29.0, 9.7
(Bortle); 29.74, 9.5 (N. A. v.d. Mey, Soesterberg, The Netherlands);
31.75, 9.9 (R. Lukas, Wilhelm Foerster Observatory).

     Recent visual magnitude estimates: Sept. 29.1 UT, 13.3 (J. E.
Bortle, Brooks Observatory); Oct. 3.83, 13.5 (G. M. Hurst,
Northampton, England); 25.0, 13.6 (Bortle); 28.0, 13.4 (Bortle).

1975 November 6                (2859)              Brian G. Marsden

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