Central Bureau for Astronomical Telegrams
IAUC 2829: N Cyg 1975
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Read IAUC 2830
Circular No. 2829
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
E. Wright, Harvard College Observatory, confirms that the
magnitude 16 star on the Palomar Sky Survey prints (cf. IAUC 2826) is
10" from the nova. R. Racine, David Dunlap Observatory, reports
that measurement of plates taken by A. Irwin shows that the magnitude
19 star is 5".5 away. It is unlikely that the proper motion of
either is sufficient to permit identification with the prenova.
Ch. Fehrenbach and Y. Andrillat, Haute Provence Observatory,
report: "Large-dispersion spectrograms obtained with the 193- and
152-cm reflectors between A3200 and A8750 on Aug. 29.9176 UT show a
practically continuous spectrum. Only H-beta and O I 7772 A are weakly
visible as wide absorption features. The interstellar (Ca II, Na I,
6280 A, etc.) and telluric lines are very narrow. The spectrum
evolved very rapidly, for on Aug. 30.8646 the following lines
appear: H (Balmer and Paschen series), O I (multiplets 1, 4, 34),
N I (1, 2), Si II (1, 2), Ca II, Na I, Fe II (27, 37, 38, 42, 74),
Ti II (13, 14) and Mg II (4). These lines are visible in absorption
- and also in emission for the most intense. The lines are
very wide, the absorptions giving a velocity of -1700 km/s. The
intensity of the lines had increased on Aug. 31. The nature of the
spectrum on Aug. 29 (before maximum) is particularly remarkable."
P. A. Strittmatter, Steward Observatory, reports that on Aug.
30 the spectrum was diffuse, with very weak P-Cyg profiles at H-alpha,
H-beta and H-gamma, He I 4471 and 3888 A, slowly strengthening during the
night; there was broad, weak emission at H and K. On Aug. 31.3 UT
there were strong, broad P-Cyg profiles. Interstellar H, K and D
lines appeared with multiple components. Between 3300 and 9700 A
the polarization was normal Cygnus interstellar with a peak value
of 1.2 percent at 5200 A.
T. Bolton and A. Gulliver, David Dunlap Observatory, report
that numerous high-dispersion spectrograms, obtained with the 188-cm
telescope between Sept. 1.13 and 1.40 UT show a spectrum similar
to that of an A supergiant with extremely broad (20 to 60 A)
absorption and emission lines. Lines of H, Fe II, Na I, Ca II, Mg
II, O I and possibly Mg I are present. The H lines to at least He
and some of the Fe II lines have P-Cyg profiles. No changes in the
spectrum were found during the observing period. The mean absorption
velocity is -1670 +/- 60 km/s; the mean emission velocity is -75
+/- 50 km/s. Some of the scatter in the velocities appears to be
real. The Balmer absorption velocities vary smoothly from -2100
km/s at H-alpha to -1400 km/s at H_10. Interstellar lines of Ca II, Na I
and CH+ are present at a velocity of -11 km/s. The equivalent
width of the interstellar K line is 0.37 A.
R. E. McCrosky and G. Schwartz, Harvard College Observatory,
report that low-resolution spectrograms show predominantly continuum
on Aug. 31.3 UT, comparable continuum and emission (H, O I, Na
I, etc.) on Sept. 1.1, and practically all emission on Sept. 3.2.
J. S. Neff, Department of Physics and Astronomy, State University
of Iowa, reports that though the continuum was weaker on Sept.
2 UT, and especially on Sept. 3, H-beta emission was comparable to that
on Sept. 1. H-alpha was becoming more intense.
P. Pesch, Warner and Swasey Observatory, communicates the
following remarks by C. B. Stephenson on a spectrogram obtained by P.
Chen on Sept. 3.1 UT with the 91-cm Cassegrain reflector: "The spectrum
shows distinct emission lines, chiefly of H and Fe II, somewhat
asymmetric in shape and with a total width of 3000 km/s. This
width is near but not beyond the upper limit of previously observed
nova spectra. The presence of broad emission in the 4600-4700 A
region makes the overall spectrum resemble McLaughlin's model nova
spectrum three magnitudes below and past maximum light."
J. Gallagher and E. P. Ney, University of Minnesota, communicate:
"Infrared photometry of the nova was obtained on Aug. 30.3 UT
using a He-cooled bolometer on the O'Brien Observatory's 76-cm
reflector. Magnitudes are V = 1.8, R = 1.4, I = 1.4, 1.2 at 1.2 um,
0.9 at 1.6 um, 0.8 at 2.2 um, 0.9 at 3.5 um, 0.5 at 4.8 um. This
energy distribution is consistent with temperatures corresponding to an
A or F spectral type, which is characteristic of a galactic nova
near maximum light. Since the V point is not depressed relative to
the infrared continuum, it is unlikely that the nova is heavily
reddened by interstellar matter."
S. G. Kleinmann, Massachusetts Institute of Technology, writes:
"Infrared photometry at 2.2, 3.5, 5, 8.4, 10.6, 11.1 and 12.6 um of
the nova and of the A2 star alpha Cyg were obtained on Aug. 30.14,
30.25 and 30.28 UT using the 130-cm telescope and bolemeter system
at Kitt Peak National Observatory. Both stars have the same infrared
colors, including a weak infrared excess, with K-N = 0.25.
During the period of these observations the infrared continuum of
the nova increased by 0.08 magnitude hr**-1 from a flux level 0.22
magnitude fainter than alpha Cyg on Aug. 30.14.
M. Turner, X-Ray Astronomy Group, University of Leicester,
telexes: "The x-ray flux from the nova, as measured with the Leicester
Sky Survey instrument on Ariel 5 on Sept. 1.7 UT, is less than
10 Uhuru flux units (3-sigma upper limit) between 2 and 20 keV. This
implies that the ratio of x-ray to optical luminosity for this nova
is 30 million times less than for A0620-00."
1975 September 4 (2829) Brian G. Marsden
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