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IAUC 5803: 1993h; V1974 Cyg

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                                                  Circular No. 5803
Central Bureau for Astronomical Telegrams
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

     Carolyn S. Shoemaker, Eugene M. Shoemaker, and David H. Levy
report their discovery of another comet.  The following positions
are available:

     1993 UT             R.A. (2000) Decl.        m1    Observer
     May  23.20885   13 24.8       -34 00        16.5   Shoemaker
          24.20572   13 24.0       -34 01                 "
          25.18776   13 23 14.45   -34 00 21.3   16.7   Scotti
          25.20008   13 23 13.82   -34 00 21.8            "
          25.21155   13 23 13.27   -34 00 22.0   16.4     "
          25.39850   13 23 04.61   -34 00 31.0          McNaught

C. S. Shoemaker, E. M. Shoemaker, and D. H. Levy (Palomar).  0.46-m
  Schmidt telescope films.  Comet moderately condensed; tail 15"
  long in p.a. 20 deg.
J. V. Scotti (Kitt Peak).  0.9-m Spacewatch telescope.  Coma diameter
  16"; narrow tail extends 2'.14 in p.a. 5 deg; m2 = 20.8 on
  May 25.20.
R. H. McNaught (Siding Spring).  Uppsala Southern Schmidt telescope.

     G. S. Stringfellow and S. Bowyer, Center for Extreme Ultraviolet
Astrophysics, University of California at Berkeley, report:
"V1974 Cyg (N Cyg 1992) was detected by the Extreme Ultraviolet
Explorer (EUVE) during the course of the all-sky survey.  V1974 Cyg
was scanned by the EUVE between 1992 Nov. 26 and Dec. 9, by which
time it had faded to V about 10.  The count rate and associated
uncertainty in the Lexan/Boron filter was 0.110 +/- 0.011 counts/s.
This bandpass is down from peak sensitivity by about an order of
magnitude at 6.0 nm and a factor of 50 at 3.0 nm.  If V1974 Cyg
lies at a distance > 0.5 kpc, then the interstellar N(H) is expected
to be of order 1.0 x 10E21 cmE-2, which should provide complete
self-absorption of the EUV flux.  Comparison of the above count
rates with those of Sco X-1, also detected by EUVE, suggests that
the EUV detections result from soft x-rays.  This implies that
V1974 Cyg had entered into a coronal phase by late November 1992.
The soft x-ray flux detected by EUVE from V1974 Cyg rivals that of
Sco X-1, making it one of the brightest soft x-ray sources in the
sky at that time."

1993 May 25                    (5803)            Daniel W. E. Green

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