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IAUC 7928: 2002ds; V4641 Sgr; C/2002 F1

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                                                  Circular No. 7928
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


SUPERNOVA 2002ds IN ESO 581-G25
     D. Hutchings and W. D. Li, University of California, report
the LOTOSS (cf. IAUC 7906) discovery of an apparent supernova (mag
about 15.9) on unfiltered KAIT CCD images taken on June 25.3 and
26.3 UT.  SN 2002ds is located at R.A. = 15h13m35s.73, Decl. =
-20o40'38".5 (equinox 2000.0), which is 67".5 east and 7".2 south
of the nucleus of ESO 581-G25.  A KAIT image taken on June 17.3
showed nothing at this position (limiting mag about 19.0).


V4641 SAGITTARII
     M. P. Rupen, V. Dhawan, and A. J. Mioduszewski, National Radio
Astronomy Observatory, report that Very Large Array (VLA)
monitoring of V4641 Sgr = SAX J1819.3-2525 shows that the source is
again active at radio wavelengths.  Following the renewed x-ray
activity in May (IAUC 7906), V4641 Sgr produced strong and variable
radio emission (e.g., IAUC 7908), with flux densities at 8.46 GHz
measured between 80 and 170 mJy at the VLA on May 23.  VLA
observations on June 5 showed no source (limiting rms noise levels
of 0.050 mJy/beam at 8.46 GHz and 0.075 mJy/beam at 4.86 GHz).  On
June 13 the source reappeared at 8.46 GHz, at 0.440 +/- 0.084
mJy/beam; at 4.86 GHz it was still not detected (rms 0.095
mJy/beam).  VLA observations on June 24 give flux densities of
1.911 +/- 0.063 and 1.22 +/- 0.085 mJy/beam at 8.46 and 4.86 GHz,
respectively.  The observations at these two frequencies were made
within 30 min of each other, so either the source varies
considerably on that timescale or it has an inverted spectrum.  In
either case, the source is probably quite small (milliarcseconds).
Given the past extreme behavior of this blackhole binary, further
radio, optical/infrared, and x-ray observations are strongly
encouraged.


COMET C/2002 F1 (UTSUNOMIYA)
     Ephemeris extension to IAUC 7909:
2002 TT     R. A. (2000) Decl.   Delta     r    Elong. Phase    m1
June 25     6 54.41   -12 22.5   2.105   1.432   37.1   25.3   11.7
     30     7 04.16   -14 37.7   2.173   1.516   38.5   24.7   12.0
July  5     7 13.57   -16 48.0   2.240   1.599   39.9   24.1   12.3
     10     7 22.69   -18 54.4   2.305   1.680   41.2   23.5   12.6
     15     7 31.55   -20 57.7   2.369   1.760   42.6   23.0   12.8
     20     7 40.17   -22 58.6   2.431   1.839   43.9   22.5   13.1
     25     7 48.56   -24 57.5   2.491   1.916   45.2   22.1   13.3

                      (C) Copyright 2002 CBAT
2002 June 26                   (7928)            Daniel W. E. Green

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