Central Bureau for Astronomical Telegrams
IAUC 5681: N Cyg 1992; 1992t
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Circular No. 5681
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
NOVA CYGNI 1992
T. Hayward, Cornell University, writes: "Recent observations
have revealed new features in the 7.5- to 13-micron spectrum of N
Cyg 1992. Spectrograms obtained with the Mt. Lemmon 1.5-m telescope
(+ HIFOGS) by D. H. Wooden and F. C. Witteborn (NASA Ames Research
Center), and A. L. Sprague (Lunar and Planetary Laboratory,
University of Arizona) on Oct. 17 and Nov. 8 (days 243 and 263 after
the eruption) show [Ne VI] 7.65-micron and [Ar III] 8.99-micron
lines, as well as the [Ne II] 12.81-micron line reported on IAUC
5497 and 5537. Low-resolution spectrograms obtained by T. Hayward,
J. Houck, and J. Miles (Cornell University) using the 5-m Hale
telescope (+ SpectroCam-10 = SC-10) on Nov. 14-15 (days 269-270)
confirm all three lines. In addition, SC-10 spectra at resolution 150
km/s resolve each line at FWHM about 2200 km/s, although about one-
third of the [Ne VI] line is totally obscured by a deep telluric
absorption feature at 7.66 microns. The following integrated
intensities are given in units of 10E-12 erg sE-1 cmE-2: [Ne VI],
218 +/- 9 on Oct. 17 and Nov. 8, 266 +/- 13 on Nov. 14-15; [Ar III],
8 +/- 3, 10.3 +/- 0.6; [Ne II], 5 +/- 1, 7.0 +/- 0.3. The [Ar III]
line is not present in similar SC-10 data taken on Aug. 9, but we
cannot rule out [Ne VI] emission on that date because of poor
atmospheric transmission that would have obscured the line. The free-
free continuum in the November SC-10 spectrum was 0.18 +/- 0.04 Jy
at 10.5 microns, but the Humphreys alpha line at 12.37 microns
reported by the Cornell group on IAUC 5497 and reobserved in August
was not detected. The appearance of the [Ne VI] and [Ar III] lines
confirm that the nova has entered a coronal line phase, and these
are the first observations of the [Ar III] line in a nova."
Visual magnitude estimates: Nov. 14.72 UT, 9.5 (H. Dahle,
Oslo, Norway); 18.79, 9.8 (M. Tombelli, Montelupo, Italy); 30.29,
10.6 (A. Mizser, Budapest, Hungary); Dec. 12.06, 9.8 (B. H. Granslo,
Fjellhamar, Norway); 15.83, 9.9 (P. Schmeer, Bischmisheim, Germany);
17.70, 9.9 (Granslo).
PERIODIC COMET SWIFT-TUTTLE (1992t)
Total visual magnitude estimates: Dec. 11.04 UT, 5.0 (R. Keen,
Mt. Thorodin, CO, 8x40 binoculars); 13.71, 5.4 (R. Haver, Tolfa,
Italy, 10x50 binoculars; 2-deg tail in p.a. 55 deg); 15.72, 5.2 (P.
Schmeer, Bischmisheim, Germany, 20x80 binoculars); 16.70, 5.4 (M.
Tombelli, Montelupo, Italy, 11x80 binoculars); 18.95, 5.2 (D. W. E.
Green, Cambridge, MA, 20x80 binoculars); 20.95, 5.2 (J. E. Bortle,
Stormville, NY, 10x50 binoculars).
1992 December 21 (5681) Daniel W. E. Green
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