Electronic Telegram No. 3435
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2013 E1 (McNAUGHT)
     R. H. McNaught reports his discovery of a comet whose images on Mar.
4.7-4.8 UT appeared soft with respect to nearby stars on CCD exposures taken
with the 0.5-m Uppsala Schmidt telescope at Siding Spring (discovery
observations tabulated below); five confirming stacked 60-s images taken on
Mar. 5.7 show a coma of diameter about 12" with a tail about 0'.2 long in p.a.
105 deg, while a similar stack from Mar. 6.5 show a strongly condensed coma
and a 0'.3 tail in p.a. 110 deg.  Following posting on the Minor Planet
Center's NEOCP webpage, other CCD astrometrists have commented on the object's
cometary appearance.  H. Sato (Tokyo, Japan; remotely with instrumentation at
the iTelescope Observatory, Siding Spring) writes that the object showed a
poorly condensed coma 15" in diameter with total V-band magnitude 18.1 on
images taken with a 0.32-m f/9 Ritchey-Chretien reflector on Mar. 6.77, while
image taken on Mar. 7.7 with a 0.51-m f/6.8 astrograph showed a strongly
condensed 16" coma with a faint 20: tail toward p.a. 110 degrees.  R. E. Hill
reports that four co-added 30-s images taken with the Mount Lemmon 1.5-m
reflector on Mar. 7.4 show a well-condensed nuclear condensation with little
coma but having a broad tail 15" long in p.a. 110 deg in 2".5 seeing.
L. Buzzi measures a diffuse coma 8" wide and a broad, fan-shaped tail at
least 11" long in p.a. around 115 deg on four stacked 120-s images taken on
Mar. 7.6 by P. Miller, P. Roche, A. Tripp, R. Miles, R. Holmes, S. Foglia,
and himself with the 2.0-m f/10 "Faulkes Telescope South" at Siding Spring
(measured by Buzzi, Foglia, and T. Vorobjov).  Buzzi adds that H. Devore,
Foglia, Vorobjov, T. Linder, and he measured sixty stacked 60-s images taken
on Mar. 8.34-8.35 by R. Holmes (Ashmore, IL, USA) with a 0.61-m f/4
astrograph, finding a diffuse coma up to 12" in size with a wide tail 12"
long centered at p.a. around 120 deg.

     2013 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar.  4.74450   12 05 54.22   -21 58 00.6   18.5   McNaught
           4.75402   12 05 53.70   -21 57 56.4   18.6     "
           4.76364   12 05 53.32   -21 57 55.3   18.7     "
           4.77332   12 05 52.73   -21 57 51.7   18.6     "
           5.70351   12 05 08.93   -21 53 34.0   18.4     "
           5.70848   12 05 08.71   -21 53 32.6   18.6     "
           5.78429   12 05 05.02   -21 53 11.4            "

     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2013-E35.

     T = 2013 Oct. 19.1368 TT         Peri. = 320.5204
                                      Node  = 134.6482  2000.0
     q = 7.649580 AU                  Incl. = 158.5665


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 March 8                     (CBET 3435)              Daniel W. E. Green