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IAUC 7073: 1998fa; 1997 SZ10, 1996 TR66; C/1995 O1

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                                                  Circular No. 7073
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1998fa IN UGC 3513
     W. D. Li, E. Halderson, M. Modjaz, T. Shefler, J.Y. King, M. Papenkova,
R. R. Treffers and A. V. Filippenko, University of California at Berkeley,
report their discovery of an apparent supernova in UGC 3513 during the
course of the Lick Observatory Supernova Search (cf. IAUC 6627) with the
0.8-m Katzman Automatic Imaging Telescope (KAIT).  The supernova was
discovered and confirmed on unfiltered observations taken on Dec. 25.4
(mag about 18.2) and 26.2 UT (mag about 18.0).  The new object is located
at R.A. = 6h42m51s.51, Decl. = +41d25'18".9 (equinox 2000.0), which is about
4".0 west and 3".8 north of the nucleus of UGC 3513.  Inspection of a KAIT
image of the same field on Dec. 22.4 showed that the supernova was present
with an unfiltered mag of 18.7.  A KAIT image on Dec. 18.3 (limiting
magnitude about 19.0) showed nothing at the position of the supernova.

1997 SZ10 AND 1996 TR66
     These transneptunian objects (MPEC 1998-Y09, 1998-Y28) have almost
certainly been identified as librating about the 1:2 mean-motion resonance
with Neptune.  Using a selection of orbital elements by B. G. Marsden,
H. F. Levison, Southwest Research Institute, and R. Malhotra, Lunar and
Planetary Institute, have established cases that are likely to be stable for
10**9 years.  For 1997 SZ10 these cases have current osculating values
a = 48.29 AU, e = 0.365, i = 11.8 deg; 48.39, 0.367, 11.8; and 48.49, 0.370,
11.8.  For 1996 TR66 representative cases have current a = 48.18 AU, e = 0.399,
i = 12.4 deg; 48.29, 0.401, 12.4; and 48.36, 0.402, 12.4.  Furthermore,
the objects currently have arguments of perihelion omega = 344 and 311 deg,
respectively, and it appears that this quantity also librates, for each
object by a few tens of degrees about a mean value near 320 deg.

     G. J. Garradd, Tamworth, N.S.W., reports that there was a remarkable
3-mag brightening of the nuclear region of this comet between his CCD
observations on Dec. 11 and 21.  A. Pearce, Nedlands, W.A., observing
visually with a 0.20-m reflector on Dec. 18.78 UT, found m1 = 11.3 and a coma
1'.0 across but noted that at low power the nuclear condensation contributed
90-95 percent of the light; at 380x the condensation was still relatively
stellar and the coma almost nonexistent.  On Dec. 19.78 the very prominent
condensation made the outer coma very faint and ill-defined.  By Dec. 25.75
the condensation had enlarged and dispersed through the coma, as in outbursts
of comet 29P 1 at comparable distances (r = 6-7 AU).

                      (C) Copyright 1998 CBAT
1998 December 26               (7073)              Brian G. Marsden

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