Central Bureau for Astronomical Telegrams
IAUC 5537: N Cyg 1992
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Circular No. 5537
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
J. P. Emerson and V. Mannings, Physics Department, Queen Mary
and Westfield College, University of London, communicate: "We
report mid-infrared (7.5-13.5 and 17-22.5 microns) spectroscopy of
Nova Cyg 1992 in a 5".5 beam using the Cooled Grating Spectrometer
#3 of the U.K. Infrared Telescope. Preliminary analysis shows a
smooth continuum at a level of about 1.0 Jy in the 10-micron window
and about 1.3 Jy (more uncertain) in the 20-micron window, with no
evidence for silicate emission features, on which are superposed
coronal and H recombination lines. The spectrum (range 7.5-13.5
microns, resolution 0.04 micron) taken over a 90-min interval
around June 5.61 UT clearly shows Ne II at 12.81 microns with peak
line flux density S = 19 Jy, and the H I recombination lines H I
7-6 (12.37 microns, S = 7 Jy), H I 9-7 (11.31 microns, S = 2 Jy),
and H I 10-7 (8.76 microns, S = 1 Jy). A line at 10.51 microns (S
= 1 Jy) may be S IV or H I 12-8. No accompanying H I 11-8 (12.38
microns) or H I 13-8 (9.39 microns) lines are seen but the former
would be blended with the stronger H I 7-6 feature and the latter
would be close to our noise level. The lines are resolved and
after removal of the instrumental resolution indicate an intrinsic
line FWHM of about 2000 km/s. A preliminary spectrogram (range
10.4-13.3 microns, resolution 0.04 micron) taken over a 40-min
interval around June 4.63 showed no clear differences from the
subsequent night. The spectrogram (range 17-22.5 microns, resolution
0.275 micron) taken over a 40-min interval around June 6.63 clearly
shows an unresolved H I 8-7 (19.06 microns, S = 3.5 Jy) recombination
line. There is possibly also a S III line (18.71 microns, S =
1 Jy) but this detection is very marginal. The strong Ne II
emission is consistent with an ONeMg nova."
D. Hanzl and F. Hroch report additional photometry obtained at
Brno (same comparison star as on IAUC 5520; +/- 0.03 unless otherwise
noted): May 6.028 UT, V = 8.47 +/- 0.02, B-V = -0.19, U-B =
-0.73; 13.011, 8.50, -0.35, -0.71; 14.047, 8.56 +/- 0.01, -0.31 +/-
0.02, -0.71 +/- 0.02; 15.047, 8.59, -0.35, -0.71; 16.030, 8.61 +/-
0.02, -0.41 +/- 0.02, -0.70 +/- 0.02; 17.959, 8.63, -0.42 +/- 0.04,
-0.72 +/- 0.04; 21.031, 8.72, -0.42 +/- 0.04, -0.70 +/- 0.05;
24.066, 8.83, -0.61, -0.58; 25.984, 8.85 +/- 0.02, -0.60 +/- 0.02,
-0.64 +/- 0.02; 26.987, 8.85 +/- 0.04, -0.56 +/- 0.04, -0.64 +/-
0.04; 29.960, 8.83 +/- 0.04, -0.54 +/- 0.05, -0.68; 30.958, 8.85
+/- 0.04, -0.53 +/- 0.04, -0.72 +/- 0.05.
B. H. Granslo, Fjellhamar, Norway, reports that Nova Cyg 1992
was estimated to be visual magnitude 8.4 at each of the following
times: June 3.96, 4.96, 6.98, 7.96, and 8.96 UT.
1992 June 10 (5537) Daniel W. E. Green
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