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IAUC 4048: 1985a; UNUSUAL OBJECT IN NGC 4618; RS Oph

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IAUC number

                                                  Circular No. 4048
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444

     This comet has been recovered by A. C. Gilmore and P. M.
Kilmartin at the Mount John University Observatory, as follows:

      1985 UT             R.A.   (1950.0)    Decl.      m2

      Mar. 20.66322     19 15 42.09     -34 23 09.4     18
           20.70766     19 15 45.86     -34 23 11.0

The object is of stellar appearance and the position in very close
agreement with the prediction by E. I. Kazimirchak-Polonskaya
(1982, Trudy Inst. Teor. Astron. 18, 91).

     J. Gibson, Jet Propulsion Laboratory, has measured the
following precise position of this object (IAUC 4042) from an plate
taken on Mar. 17 by J. Schombert with the 1.2-m Palomar Schmidt
telescope: R.A. = 12h39m09s56, Decl. = +41deg25'32"7 (equinox 1950.0).
     A. V. Filippenko, University of California at Berkeley; and
W. L. W. Sargent, California Institute of Technology, confirm that
the object is a peculiar supernova.  It is visible on photographic
plates taken by E. A. Harlan at the Lick Observatory on Mar. 16,
whereas similar plates obtained on 1914 May 26 show only a bright
H II region at the same location.  Spectrophotometry on 1985 Mar.
17 and 19 with the Shane 3-m telescope reveals several prominent,
broad emission lines in spectral regions not observed previously.
Possible identifications are K I 404.6, [N I] 519.9, [O II] 732.5
and O I 777.4 nm.  Note that the FWZI of the strongest line ([O I]
630.0 nm) is over 25 000 km/s, not 15 000 km/s as stated on IAUC
4042.  This type of supernova may be the progenitor of certain
oxygen-rich remnants such as Cas A and the one in NGC 4449.

     Visual magnitude estimates: Feb. 16.25 UT, 7.6 (K. Medway,
Southampton, England); 19.54, 8.5 (L. Cook, Concord, CA); 21.42,
8.3 (J. Bortle, Stormville, NY); 23.75, 8.6 (R. H. McNaught,
Coonabarabran, N.S.W); 25.76, 8.8 (McNaught); 28.34, 9.1 (Bortle);
Mar. 4.22, 8.8 (G. M. Hurst, Basingstoke, England); 4.22, 9.2 (S.
Lubbock, Bridgend, Wales); 5.23, 9.3 (Medway); 6.22, 9.4 (Medway).

1985 March 21                  (4048)              Brian G. Marsden

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