Central Bureau for Astronomical Telegrams
IAUC 3296: N Cyg 1978
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Circular No. 3296
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
NOVA CYGNI 1978
E. F. Guinan, G. P. McCook and J. D. Dorren, Villanova University,
write: "Photoelectric wide- and narrow-band observations centered
near the rest wavelengths of H-alpha (6563 A) and the O I triplet
(7774 A) have been made on 18 nights from Sept. 15 to Oct. 13. Over
this time net fadings of ~ 2.60 and 1.15 magnitude have been found
in the wide bandpasses at 7790 A and 6585 A, respectively. The rate
of decline is not steady, and several changes of slope occurred.
During Sept. 26.03-26.70 UT an increase in light of ~ 0.3 magnitude
occurred, followed by a decline by about the same amount until Sept.
27.20. The observations near Sept. 26.70 were made by Dorren at
Biruni Observatory, Shiraz, Iran, at 6585 A. In addition cyclic
light variations with 'periods' between 20 and 80 min and amplitudes
up to 0.01 magnitude were observed on about 30 percent of the
nights. Abrupt changes in brightness have also been observed on
timescales of minutes. Intense H-alpha emission and strong emission at
the O I triplet have also been observed, with the net emission measured
in the narrow bandpass relative to its corresponding wide bandpass
still increasing slowly at Oct. 13 UT."
R. D. Gehrz, G. L. Grasdalen, J. A. Hackwell and F. P. Ney,
University of Wyoming, write that infrared observations with the
230-cm telescope show that a dust-formation phase started between
Oct. 7 and 15. Visual observations are urged. Infrared results:
1978 UT 2.3 um 3.6 um 4.9 um 8.6 um 10.0 um 11.4 um 12.6 um
Oct. 7.2 7.1 5.8 5.3 4.4 4.4 4.3 3.5
15.2 6.5 5.0 4.4 3.7 3.7 3.5 3.0
19.2 5.6 4.1 3.1 3.1 3.3 - 2.5
20.2 5.6 3.9 3.0 2.2 2.4 2.1 1.6
T. E. Margrave, University of Montana, communicates further
photoelectric observations, obtained with the 40-cm reflector at
the Blue Mountain Observatory: Oct. 5.351 UT, V = 9.11, B-V = +0.22,
U-B = -0.67; 6.263, 9.32, +0.24, -; 7.263, 9.37, +0.21, -0.64;
9.326, 9.18, +0.23, -0.65; 10.260, 9.47, +0.19, -0.67. Comparison
stars were HD 206280 and BD +4903615 (assuming the magnitudes and
colors in the USNO Catalogue). A series of 87 V-filter observations
during Oct. 7.254-7.381 showed the nova to brighten by ~ 0.15 magnitude,
with fluctuations on timescales of minutes to hours; 40 observations
during Oct. 9.318-9.409 showed rather constant mean brightness
but amplitude fluctuations of ~ 0.12 magnitude in 20 min.
1978 October 24 (3296) Brian G. Marsden
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