Central Bureau for Astronomical Telegrams
IAUC 2834: N Cyg 1975
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Read IAUC 2835
Circular No. 2834
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
NOVA CYGNI 1975
The following photoelectric magnitudes have been reported:
1975 UT V B - V U - B V - R V - I Observer
Aug. 29.67 3.42 +0.05 -0.07 Kozai
30.23 2.04 +0.50 -0.44 Florkowski
30.30 2.04 +0.52 -0.34 "
Sept. 1.161 2.45 +0.62 -0.29 Uckotter
2.254 3.75 +0.35 -0.50 "
2.94 4.35 +0.38 -0.75 Purola
3.115 4.51 +0.38 -0.65 +1.40 +2.04 Fernie
3.307 4.62 +0.26 -0.54 Uckotter
3.350 4.65 +0.36 -0.61 +1.45 +2.05 Fernie
3.86 4.89 +0.42 -0.67 Purola
4.194 5.09 +0.30 Uckotter
4.289 5.14 +0.25 "
5.87 5.59 +0.40 -0.68 Purola
7.93 6.12 +0.39 -0.69 "
8.95 6.31 +0.35 -0.67 "
Y. Kozai et al. (Tokyo Astronomical Observatory).
D. R. Florkowski and J. P. Oliver (Rosemary Hill Observatory). 76-cm
reflector. Accuracy 0.01 magnitude. Comparison star rho Cyg.
Distance deduced as 1.3 to 2.3 kpc. The expanding shell can be
expected to have a diameter of 0".1 in five to nine months.
D. Uckotter and C. Zellner (Dyer Observatory). 61-cm reflector.
Because of haze the accuracy is no better than 0.03 to 0.05
magnitude. Comparison star 55 Cyg. Communicated by A. Heiser.
V. Piirola (Helsinki Observatory). Comparison star HR 8020.
J. D. Fernie and S. E. Clarke (David Dunlap Observatory). Errors ~
0.01 magnitude. Comparison stars HR 7977, 8001, 8089 and 8252.
The following recent visual magnitude estimates have been
reported: Sept. 10.03 UT, 6.5 (L. Jacchia, Cambridge, Massachusetts);
10.04, 6.4 (S. O'Meara, Cambridge, Massachusetts); 10.12, 6.5 (D.
di Cicco, Waltham, Massachusetts); 11.06, 6.8 (Jacchia); 12.06, 6.6
(C. Sherrod, North Little Rock, Arkansas).
P. Tempesti, Collurania Observatory, reports that photoelectric
monitoring in V during Sept. 9.86-10.13 UT shows a periodic
variation of amplitude 0.1 magnitude and period 3.2 hours.
V. Piirola, Helsinki Observatory, notes that the linear
polarization has increased slightly since Aug. 30.9 UT (cf. IAUC 2828).
On Sept. 2.94 the results were: in V, 1.29 percent in p.a. 47o.2; in
B, 1.28 percent in 47o.0; in U, 1.20 percent in 46o.6. Since then
the polarization has been practically constant (until Sept. 8.98).
Y. Kozai, Tokyo Astronomical Observatory, reports that on Aug.
29.7 UT the spectrum was featureless except for the interstellar
lines and very shallow, broad H absorption lines. Good series of
spectrograms were obtained at Okayama (dispersion 4 to 20 A/mm) and
Dodaira (60 A/mm at H-gamma). The absorption components (mainly H and
Fe II) strengthened after Aug. 30. The emission components, barely
visible on Aug. 30, were greatly enhanced after Sept. 1. The H
emission corresponds to an expansion velocity of +/- 1500 km/s. On
Sept. 3 the nova was beginning to develop through the Orion to the
nebular stage, although no forbidden lines were seen on Sept. 4.
S. Wyckoff and P. A. Wehinger, Wise Observatory, communicate:
"Spectrograms in the range 3000-9000 A with dispersions 45, 90 and
240 A/mm were obtained on Sept. 1.8, 2.8, 3.8 and 4.8. Strong,
broad, Balmer line emission was accompanied by weak, broad absorptions
displaced by -2000 km/s. There were moderately strong, broad
emission lines of Fe II (multiplet 42) and Na I. The following
changes in the emission features were observed between Sept. 1.8
and 4.8: the Balmer continuum strengthened; a very broad feature
associated with Mg II 4481 A weakened; O I 7772 A and 8446 A strengthened;
broad features at 4173, 4234, 7480 and 8710 A weakened; a
broad feature appeared at 7080 A on Sept. 4.8; broad features at
8222 and 8680 A did not change."
R. W. Thompson and W. F. Rush, Ritter Observatory, write:
"Time-resolved spectra (time resolution ~ 7 min, dispersion 39 A/mm)
taken on Sept. 7.2-7.4 and 8.1-8.2 UT with the 100-cm reflector
show extremely strong H-alpha emission with a total width of ~ 3500
km/s. Four emission peaks are evident. Night to night variation
in the H-alpha profile is apparent with possible variability on short
time scales. With the H-alpha emission well exposed, no continuum was
visible over the wavelength interval 5800-6800 A."
U. Fink, H. Larson and N. Gautier, Lunar and Planetary Laboratory,
report that the infrared spectrum between 0.86 um and 4.0 um
was observed on Sept. 10 UT with the Steward Observatory's 229-cm
reflector on Kitt Peak. The resolution was 1.5 wavenumbers. The
infrared spectrum is dominated by emission lines of H and He. The
strongest line observed was P-beta (1.28 um), followed by He I at 1.08 um,
which was combined with P-gamma (1.09 um). Also observed were P-delta (1.00
um), B-gamma (2.16 um), He I at 2.06 um and several unidentified lines.
The lines were quite broad, corresponding to a velocity of about
4000 km/s, and some of them showed possible P-Cyg profiles. The
continuum was present basically at 1.5 um and longward.
1975 September 12 (2834) Brian G. Marsden
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