Central Bureau for Astronomical Telegrams
IAUC 3276: N Cyg 1978
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Circular No. 3276
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
R. Reginaldo, Agrupacion Astronomica de Sabadell, provides the
following prediscovery observations: Sept. 9.00 UT, mpg = 8.7 (G.
Gimferrer and C. Schnabel); 9.96, 8.0? (J. Genebriera).
S. Ortolani, P. Rafanelli, L. Rosino and A. Vittone, Asiago
Astrophysical Observatory, write: "Spectrograms of Nova Cyg 1978
were obtained at Asiago during Sept. 12-16 with the two-prism
spectrograph on the 122-cm telescope and the echelle spectrograph
(dispersion 6 A/mm) on the 182-cm telescope at Mt. Ekar. On Sept.
12-13 the absorption spectrum of the nova was estimated as closely
similar to that of an F5Ib supergiant, with a multitude of relatively
narrow absorption lines (H, Fe I, Fe II, O I, N I, N II, Sr II,
Ti II, Sc II, etc.) displaced blueward by ~ -630 km/s and a few
weak emissions. H-alpha was strong in emission. Sharp interstellar
lines of Ca II (H and K) and Na I (5890-5896 A) were visible in the
spectrum. On the following days the spectra were characterized by
the strengthening of wide emission bands, mostly due to H, Fe II
(multiplets 27, 42, 48, 49 and 74), Ti II, N II, Na I, partly overlapped,
and by the progressive weakening of the absorption features.
O I was present with the infrared line at 7774 A and the forbidden
lines at 6300-6364 A, still weak. On Sept. 16-17 only a few diffuse
absorption bands were observed at the blue edge of the emission
features, over a fairly strong continuum, while all of the
other absorption features had disappeared. The mean radial velocities
of the ejected shells, derived by preliminary measures on
echelle spectrograms, were: on Sept. 13, -630 km/s; 14, -636 km/s;
15, -622 km/s; 16, -729 km/s. However, much higher velocities, of
the order of 1550 km/s, were derived from the halfwidth of some
Balmer lines. The near infrared (up to 7800 A) was rather flat,
with only the emission line of O I at 7774 A."
M. L. Sitko, Washburn Observatory, writes: "The diffuse
interstellar feature at 6614 A was observed in the spectrum of Nova Cyg
1978 on Sept. 15.1 UT by C. M. Anderson, K. H. Nordsieck and myself
using the 91-cm telescope at the Pine Bluff Observatory,
equipped with the Wisconsin echelle spectrograph and intensified
Reticon solid-state detector. The overall resolution was 300 mA.
The equivalent width of this feature was found to be 80 +20/-30 mA.
From the correlation plots found in Herbig (1975, Astrophys. J.
196, 129) this line strength is consistent with E(B-V) = -0.3 +0.2/-0.1.
Errors quoted allow for maximum uncertainties."
1978 October 3 (3276) Brian G. Marsden
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