Central Bureau for Astronomical Telegrams
IAUC 2973: V1500 Cyg; UNUSUAL NEW FLARE STAR
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Circular No. 2973
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
Western Union: RAPID SATELLITE CAMBMASS
V1500 CYGNI
J. C. Kemp, Department of Physics, University of Oregon, reports
that observations during June 30-July 2 with the 224-cm
telescope at Mauna Kea showed a mean magnitude of ~ 10.7 in unfiltered
(UBV) light. Rapid light variation or flickering was detected on a
timescale of the order of 1 min, with typical peak-to-peak amplitude
0.027 magnitude; the flickering was definite, checked by comparison
with a field star of comparable brightness at alternate intervals of
10 min on all three nights. No periodicity was determined,
although power spectra will be computed; the rapid variations
were studied mainly in unfiltered light but were also seen in
various filter bands and appeared stronger in the red. Variations
on a timescale of 2-5 hours were also noted, the peak-to-peak
amplitude being about 0.28 magnitude in unfiltered light; the time
span was not long enough to establish a periodicity, but if there
is regularity, the variation on this timescale appears to be sinusoidal
rather than eclipsing. Assuming a sine wave, the data on the
three nights are found to be consistent with periods of 3.3, 3.8 or
4.6 hours; the last period is to be preferred, but the first one
agrees better with the observations by Tempesti in Sept. 1975 (IAUC
2834). A light maximum occurred on July 1.60 UT. The linear
polarization in the band 4000-6000 A was 1.07 percent in p.a. 47o.3 on
June 30.58 UT and 1.20 percent in p.a. 49o.8 on July 1.57 UT.
E. Leibowitz, Wise Observatory, reports that observations in
the B band revealed a continuous rise by 0.23 magnitude around B =
10.7 between July 5.00 and 5.03 UT and a similar rise around the
same magnitude between July 5.97 and 6.02 UT.
J. Bortle, Brooks Observatory, provides visual magnitude
estimates as follows: June 18.15 UT, 11.4; 27.10, 11.5; July 6.1, 11.6.
UNUSUAL NEW FLARE STAR
H. E. Bond, University of Washington, writes that an objective-prism
plate taken with the Curtis Schmidt telescope at Cerro Tololo
Interamerican Observatory shows that a star located at R.A. = 23h29m09s,
Decl. = -3o01'.7 (equinox 1950.0) abruptly appeared at mpg ~ 8.5 on June
7d09h59m UT and was still well above the plate limit of mpg ~ 10.5
when the exposure ended 14 min later. The spectrum was continous
with the Balmer lines and probably Ca II K in emission. On the
Palomar Sky Survey the object was as faint as magnitude about 15.0.
1976 July 12 (2973) Brian G. Marsden
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