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IAUC 5169: 1991A; 1990o

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IAUC number 

                                                  Circular No. 5169
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 or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN


SUPERNOVA 1991A IN IC 2973
     A. V. Filippenko, University of California at Berkeley,
communicates: "Fully-calibrated spectra of SN 1991A (cf. IAUC 5155)
confirm that the object is a type-Ic supernova, probably within two
weeks past maximum brightness.  However, a very weak, broad component
of H-alpha emission is almost certainly present, suggesting
that type-Ic supernovae are related to type-II objects.  Careful
scrutiny of the two-dimensional CCD spectra reveals that the very
strong, narrow H-alpha emission mentioned in IAUC 5155 is actually a
hot spot on the detector.  Furthermore, in comparison with [O III]
500.7-nm, [O III] 436.3-nm emission is very weak if present at all.
Thus, there is no compelling evidence for dense circumstellar material,
and the classification of SN 1991A is unlikely to change as it
ages.  The object is superposed on a relatively compact H II region
whose Balmer decrement yields a visual extinction of 0.4 mag.  The
very small equivalent width of the Na I D absorption line in the
spectrum of the SN is consistent with an upper limit of about 0.4
mag for the extinction."


PERIODIC COMET SHOEMAKER-LEVY 1 (1990o)
     Extension to the ephemeris on IAUC 5143, from orbital elements
on MPC 17595:

     1991 ET      R.A. (1950) Decl.     Delta      r       m1
     Jan. 24     2 27.47    +25 19.8    1.734    2.132    15.0
     Feb.  3     2 41.74    +27 18.4
          13     2 57.12    +29 03.8    2.113    2.287    15.7
          23     3 13.41    +30 37.5
     Mar.  5     3 30.42    +32 00.8    2.503    2.446    16.4
          15     3 48.01    +33 14.3
          25     4 06.05    +34 18.6    2.891    2.607    17.0
     Apr.  4     4 24.40    +35 14.1
          14     4 42.97    +36 01.1    3.264    2.768    17.5
          24     5 01.65    +36 40.0
     May   4     5 20.34    +37 11.1    3.608    2.929    18.0
          14     5 38.95    +37 35.0
          24     5 57.39    +37 52.1    3.914    3.089    18.4


1991 January 18                (5169)             Daniel W. E. Green

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