Electronic Telegram No. 4373
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
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Prepared using the Tamkin Foundation Computer Network


COMET C/2017 E4 (LOVEJOY)
     Terry James Lovejoy, Birkdale, Queensland, Australia, reports his
discovery of a diffuse comet on three CCD 8-s exposures taken five minutes
apart starting on Mar. 9.684 UT (discovery observations tabulated below) with
a Celestron C14 reflector operating at f/1.9 (+ QHY9 camera); there was a
central condensation around magnitude 16 with a faint, diffuse coma that
could be traced more than 1' in diameter.

     2017 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar.  9.68448   18 50 54.15   -32 58 34.3   15.0   Lovejoy
           9.68767   18 50 55.21   -32 58 25.2   14.7     "
           9.69095   18 50 56.29   -32 58 14.9   15.1     "

After the object was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists also reported on its cometary appearance.  M. Mattiazzo,
Swan Hill, Victoria, Australia, writes that six stacked 30-s exposures taken
on Mar. 10.7 UT with a Celestron C11 f/3.3 reflector at Swan Hill, Victoria,
Australia, show a diffuse coma about 1'.0 in diameter with a nuclear
condensation of red mag about 14.5 and no apparent tail.  E. Guido,
Castellammare di Stabia, Italy, notes that ten stacked 30-s unfiltered
exposures obtained remotely with an iTelescope 0.50-m f/6.8 astrograph at
Siding Spring on Mar. 10.7 show that this object is a comet with a diffuse
coma nearly 15" in diameter.  Ten stacked 60-s images taken by C. Jacques, E.
Pimentel, and J. Barros with a 0.43 m f/6.8 astrograph at Siding Spring on
Mar. 10.7 show a diffuse coma 40" in diameter and a central condensation of
diameter 11", but with no apparent tail.  A. Novichonok, Petrozavodsk State
University, Russia, took six unfiltered 60-s images remotely with a 0.43-m
f/6.8 astrograph at Siding Spring on Mar. 10.73, which show a diffuse and
slightly condensed coma with diameter about 0'.4-0'.5 and no apparent tail;
the total red magnitude as measured inside a 0'.55-square aperture was about
15.0.  H. Sato, Tokyo, Japan, stacked ten 30-s exposures obtained on Mar.
10.8 with a 0.40-m f/3.5 astrograph (+ luminance filter) at Siding Spring
to find a strongly condensed round coma 2'.8 in diameter with no apparent
tail; the w-band magnitude was 11.8 as measured within a circular aperture
of radius 85".6.  Images taken by T. Linder and R. Holmes with a 0.61-m
f/6.5 Dall-Kirkham Astrograph at Cerro Tololo on Mar. 11.34 show an obvious
15" coma.  E. Bryssinck, Kruibeke, Belgium, reports that thirteen stacked
60-s exposures taken on Mar. 11.7 remotely with a 0.15-m f/7.3 refractor (+
luminance filter) at Siding Spring, Australia, show a central condensation
with a circular faint coma 76" in diameter in interfering moonlight; the R
magnitude was 16.0 as measured within a circular aperture of radius 5".05.
Images taken by S. Foglia, L. Buzzi, P. Concari, C. Cremaschini, G. Galli,
and M. Tombelli with a 0.15-m f/7 refractor at Siding Spring on Mar. 11.8
show a coma 20" in diameter and central condensation; their image has
been posted at URL http://www.asteroids.altervista.org/TJL006/TJL006.htm.
K. Kadota, Ageo, Japan, finds a diffuse of diameter 1'.5 with a central
condensation (mag 12.7) and no tail in images taken with a 0.25-m f/5
reflector on Mar. 11.84 in twilight at low altitude.  Images taken by G.
Masi and M. Schwartz (and measured by Masi and P. Holvorcem) on Mar. 12.51
with the Tenagra II 0.41-m f/3.75 reflector near Nogales, Arizona, shows
the comet to be clearly diffuse and elongated for about 10" in the
east-west direction.
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams, and an ephemeris appear on MPEC 2017-E86.

     T = 2017 Apr. 23.2918 TT         Peri. =  87.2154
                                      Node  = 223.1687  2000.0
     q = 0.493573 AU                  Incl. =  88.2309


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

                         (C) Copyright 2017 CBAT
2017 March 13                    (CBET 4373)              Daniel W. E. Green