[Iaude] CBET 4580: 20181203 : A/2018 W1 AND COMET C/2018 W2

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 4580
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau at eps.harvard.edu (alternate cbat at iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


A/2018 W1 AND COMET C/2018 W2
     Nearly simultaneous independent discoveries of a comet were reported on
Nov. 27 via CCD images taken by H. Groeller (with the Catalina Sky Survey
0.68-m Schmidt telescope) and by B. M. Africano (with the Mount Lemmon 1.5-m
reflector).  Groeller noted that four co-added 30-s exposures show a "solid"
coma with an apparent tail in p.a. 230-300 degrees; he indicated that the
object was extended to a size of about 5"-7".  Africano found the comet near
the edge of his field-of-view; co-added 30-s images show a bright, compact
core 5"-8" across with a possible tail extending several arcsec from the
core and spanning p.a. 255-260 deg.  The discovery observations are
tabulated below.  (G. V. Williams notes that Africano reported the object
first, and that the object was posted on the Minor Planet Center's NEOCP
webpage before Groeller's report arrived.  The Central Bureau received
Africano's report at around Nov. 27.55 UT, or 21 minutes before Groeller's
report was received.)

     2018 UT             R.A. (2000) Decl.       Mag.   Observer
     Nov. 27.51078   12 59 43.44   +44 16 32.9   18.2   Groeller
          27.51494   12 59 43.65   +44 16 36.8   18.4     "
          27.51911   12 59 44.01   +44 16 39.1   18.3     "
          27.52327   12 59 44.24   +44 16 42.9   18.2     "
          27.53001   12 59 44.75   +44 16 47.1   18.3   Africano
          27.53596   12 59 45.13   +44 16 51.3   18.3     "
          27.53893   12 59 45.30   +44 16 53.0   18.4     "

The available astrometry and the following preliminary parabolic orbital
elements by Williams (from 31 observations spanning Nov. 27-Dec. 2)
appear on MPEC 2018-X23.

     T = 2019 Sept.15.6289 TT         Peri. = 153.6696
                                      Node  = 179.9483  2000.0
     q = 1.590666 AU                  Incl. = 115.1117

     An apparently asteroidal object designated A/2018 W1 by Williams with
elliptical orbital elements (T = 2019 May 11.86 TT, e = 0.937, q = 1.36 AU,
P = 100 yr), currently at mag 19 and about 2.5 AU from the sun, was discovered
on images obtained by G. J. Leonard on Nov. 2.5 UT with the Catalina 0.68-m
Schmidt telescope; astrometry and orbital elements appear on MPEC 2018-X14.


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

                         (C) Copyright 2018 CBAT
2018 December 3                  (CBET 4580)              Daniel W. E. Green