[Iaude] CBET 4522: 20180609 : COMET C/2018 L2 (ATLAS)

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Jun 8 18:46:09 EDT 2018


                                                  Electronic Telegram No. 4522
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


COMET C/2018 L2 (ATLAS)
     Another comet has been discovered on eight o-band CCD images obtained
on June 6 with a 0.5-m f/2 Schmidt reflector at Mauna Loa, Hawaii, in the
course of the "Asteroid Terrestrial-impact Last Alert System" (ATLAS) search
program (discovery observations tabulated below).  H. Weiland notes that the
comet has a size of 8".75, larger than stellar profiles, in the discovery
exposures.

     2018 UT             R.A. (2000) Decl.       Mag.
     June  6.33235   13 55 17.30   -42 18 14.0   15.6
           6.33604   13 55 17.11   -42 18 08.0   15.6
           6.34020   13 55 16.90   -42 18 00.9   15.6
           6.34392   13 55 16.73   -42 17 54.9   15.7
           6.34805   13 55 16.51   -42 17 47.8   15.6
           6.35176   13 55 16.31   -42 17 41.3   16.3
           6.35592   13 55 16.13   -42 17 34.5   15.6
           6.35961   13 55 15.98   -42 17 28.3   15.7

After the comet was posted on the Minor Planet Center's NEOCP and PCCP
webpages, other CCD astrometrists also commented on the object's cometary
appearance.  L. S. Amaral, Rio de Janeiro, Brazil, reports that three 60-s
exposures taken with a 0.31-m f/2.9 reflector (measured by P. R. Holvorcem)
on June 4.1 UT shows a diffuse coma of diameter 8" and red magnitude
15.3-15.8.  A 10-s exposure taken by T. Linder and R. Holmes with a 0.61-m
f/10 astrograph at Cerro Tololo on June 6.99 shows a large, bright coma 15"
in size.  Five stacked 60-s exposures taken on June 7.0 by C. Jacques, E.
Pimentel, and J. Barros with a 0.45-m f/2.9 reflector at the SONEAR
Observatory at Oliveira, Brazil, shows a coma of diameter 21" and a tail
27" long in p.a. 92 degrees.  Exposures taken by A. C. Gilmore and P. M.
Kilmartin with the Mount John 1.0-m f/7.7 reflector at Lake Tekapo, New
Zealand, on June 8.4 show a diffuse fringe around the southeast quadrant
of the comet's image (full-width-at-half-maximum 3".9, vs. comparable
stars with FWHM 2".5).
     The available astrometry, the following preliminary parabolic orbital
elements by G. V. Williams (from 50 observations spanning June 4-8), and
an ephemeris appear on MPEC 2018-L37.

     T = 2018 Dec.  2.3969 TT         Peri. =  55.9849
                                      Node  = 242.9071  2000.0
     q = 1.717757 AU                  Incl. =  67.6514


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

                         (C) Copyright 2018 CBAT
2018 June 9                      (CBET 4522)              Daniel W. E. Green



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