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IAUC 7364: C/2000 C2, C/2000 C3, C/2000 C4, C/2000 C5, C/2000 C6; AX J1740.2-2848

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                                                  Circular No. 7364
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)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)


COMETS C/2000 C2, C/2000 C3, C/2000 C4, C/2000 C5, C/2000 C6
    D. A. Biesecker, SM&A Corporation and Goddard Space Flight
Center, reports measurements of five comets observed with the
coronagraphs aboard SOHO; the discovery observations are given
below, while the astrometry and orbital elements appear on MPEC
2000-C50 through 2000-C54.  Only C/2000 C6 appears to be a Kreutz
sungrazer; it was first noticed by T. Lovejoy on SOHO web images,
and Biesecker notes that its brightness ranged from V = 8.7 on Feb.
9.43 to 7.7 on Feb. 9.68 UT, and the comet showed a tail at 13
solar radii on C3 images.  The other comets showed no tail.  C/2000
C2 first noted by K. Cernis, remained relatively stable in
brightness (V = 6.5-6.9) during Feb. 3.70-3.84.  C/2000 C3, found
by Biesecker, brightened from V = 6.7 on Feb. 4.59 to 5.9 on Feb.
4.79, before fading to V = 7.0 on Feb. 5.09.  C/2000 C4, found by
M. Meyer, was on a trajectory closely following that of C/2000 C3,
and it was assumed that the orbits are identical with a difference
Delta(T) = 0.60 day.  C/2000 C4 brightened from V = 5.9 on Feb.
5.17 to 4.9 on Feb. 5.30, before fading to V = 6.7 on Feb. 5.67.
C/2000 C5, found by M. Oates, was at V = 7.5-8.0 on Feb. 7.  Comets
C/2000 C2 and C/2000 C5 may also be related to each other.

     2000 UT           R.A. (2000) Decl.        Comet
     Feb.  3.704      21 12.3      -15 11       C/2000 C2
           4.563      21 16.4      -15 27       C/2000 C3
           5.163      21 18.6      -15 15       C/2000 C4
           7.788      21 28.1      -13 47       C/2000 C5
           9.221      22 00.3      -17 13       C/2000 C6


AX J1740.2-2848
     M. Sakano and K. Koyama, Kyoto University, write:  "A post-
facto analysis of the ASCA Galactic Center Survey data obtained on
1998 Sept. 7-8 shows a coherent pulsation of 729 +/- 14 s from AX
J1740.2-2848 (located at R.A. = 17h40m11s.6, Decl. = -28o47'48",
equinox 2000.0; 90-percent-confidence error radius 30").  The x-ray
spectrum is fitted by a power law with photon index 0.7 (+0.7,
-0.5), absorbed by log N_H = 22.5 (+0.3, -0.4).  The pulsation,
flat spectrum, and large absorption support AX J1740.2-2848 as a
new x-ray binary pulsar near the Galactic center.  The x-ray
luminosity in the band 2-10 keV was 3 x 10**34 erg/s at a distance
of 8500 pc."

                      (C) Copyright 2000 CBAT
2000 February 12               (7364)            Daniel W. E. Green

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