Central Bureau for Astronomical Telegrams
IAUC 5756: 1993J; 1993a; U Gem
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Circular No. 5756
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)
SUPERNOVA 1993J IN NGC 3031
J. C. Wheeler and A. Clocchiatti, University of Texas, report:
"Spectrograms (range 500-850 nm; dispersion 0.7 nm/pixel) obtained
with the Imaging Grism Instrument on the 0.76-m telescope of
McDonald Observatory on Apr. 6.3 and 7.3 UT show the onset of
strong H-alpha and distinct P-Cyg profiles. The raw supernova
spectrum was crudely corrected for instrumental effects by observing
a nearby DA dwarf (GRW+705824 = EG102), fitting a polynomial to
its continuum, and dividing the raw supernova spectrum by that
polynomial. The result reveals that the spectrum on Apr. 7.3 has
an emission peak at 654.5 nm of 29 nm FWHM with a broad minimum at
616.3 nm. The emission is roughly six times stronger than the
absorption, appears to have sharp blue and red edges at 637 and 681
nm, respectively, and is asymmetric with a stronger red wing. This
emission is most readily identified with H-alpha. The lack of deep
absorption may indicate fluorescence from circumstellar material,
which may affect the location of the minimum. Another feature
shows a P-Cyg profile with a maximum at 588.4 nm and a well-defined
minimum at 566.5 nm; this feature could be either He I 587.6 nm or
Na D. For He I, the minimum represents a velocity of 10 760 km/s.
The emission is approximately as strong as the absorption. The
peak also shows a narrow absorption line of interstellar Na D.
Another broad mimimum appears at about 500 nm. Pending more accurate
reduction, the spectrum resembles that of the type-II linear
supernova 1979C on 1979 May 28 (Branch et al. 1981, Ap.J. 244,
780), although identification of the nature of the event at this
time is premature."
COMET MUELLER (1993a)
Total magnitude estimates, visual except those by Mikuz (cf.
IAUC 5699): Feb. 1.17 UT, 13.3 (H. Mikuz, Ljubljana, Slovenia,
0.20-m f/2 Baker-Schmidt camera + V filter + ST-6 CCD); 14.58, 13.3
(A. Nakamura, Kuma, Japan, 0.60-m reflector); 18.36, 13.2 (A. Hale,
Las Cruces, NM, 0.41-m reflector); Mar. 10.81, 13.6 (Mikuz); 15.90,
12.7 (T. Vanmunster, Landen, Belgium, 0.35-m reflector); 26.93,
13.5 (Mikuz).
U GEMINORUM
Corrigendum. On IAUC 5722, line 6, for 19.54, 11.1 read
19.34, 11.1
1993 April 8 (5756) Daniel W. E. Green
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