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IAUC 7418: C/2000 J2; XTE J1118+480; C/1999 S4

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IAUC number

                                                  Circular No. 7418
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)

COMET C/2000 J2 (SOHO)
    D. A. Biesecker, Emergent Information Technologies, Inc., and
Goddard Space Flight Center, reports observations of another comet
found in LASCO C2 data by M. Oates via the SOHO website.  The comet
brightened from V = 7.8 on May 7.254 UT to 7.1 on May 7.368, but
had faded to V = 8.3 on May 7.452, and it was not seen in the C3
instrument.  No tail was evident.  Astrometry (measured by
Biesecker, reduced by B. G. Marsden) and orbital elements appear on
MPEC 2000-J32; this comet is evidently not a Kreutz sungrazer.

     2000 UT           R.A. (2000) Decl.
     May  7.243       3 01.7       +17 22

XTE J1118+480
     M. Uemura, Kyoto University, reports on behalf of the VSNET
XTE J1118+480 collaboration team:  "Unfiltered CCD photometry of
this x-ray transient (cf. IAUC 7389) has been undertaken since Mar.
30 by numerous observers around the world (M. Uemura, T. Kato, K.
Matsumoto, M. Honkawa, L. Cook, B. Martin, G. Masi, A. Oksanen, M.
Moilanen, R. Novak, and Y. Sano).  Analysis of the combined light
curve (covering 37 days) revealed the growth of the periodic
variation profile from sinusoidal to 'asymmetric humplike'.  The
period has significantly changed from 0.1709(3) day during Mar.
30.7-Apr. 1.4 UT to 0.1703(1) day during Apr. 26.8-May 5.7.  The
period change strongly suggests that the optical modulation not
only reflects the orbital modulation but also shows for the first
time ongoing development of superhumps in a blackhole transient
(e.g., Bailyn 1992, Ap.J. 391, 298; Mineshige et al. 1992, PASJ 44,
L15; O'Donoghue and Charles 1996, MNRAS 282, 191).  We invite
worldwide observers to join the VSNET collaboration team as part of
a simultaneous multiwavelength campaign.  An ASCA x-ray pointing
observation (led by Y. Ueda) in the band 0.5-10 keV is planned
between May 11.5 and 12.0.  More detailed information can be seen
at http://www.kusastro.kyoto-u.ac.jp/vsnet/Xray/xtej1118-camp.html."

     This comet was detected low in the morning sky by K. Kadota,
Ageo, Saitama, Japan (0.18-m reflector + CCD) at m_1 about 13.0 on
May 4.78 UT (coma diameter 0'.4).

                      (C) Copyright 2000 CBAT
2000 May 9                     (7418)            Daniel W. E. Green

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