[Iaude] CBET 4527: 20180622 : COMET P/2018 L4 (PANSTARRS)

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Jun 22 14:13:18 EDT 2018


                                                  Electronic Telegram No. 4527
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)
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Prepared using the Tamkin Foundation Computer Network


COMET P/2018 L4 (PANSTARRS)
     R. Weryk, Institute for Astronomy, University of Hawaii, writes that R.
Wainscoat suspects an object found on images taken in 1".0 seeing on June 8.5
UT with the 1.8-m Pan-STARRS1 Ritchey-Chretien telescope at Haleakala is a
faint comet.  Weryk then obtained three 60-s gri-band confirming exposures
with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea (with C. Crowder
and A. Petric), which show a 6" tail in p.a. about 200 degrees; the comet's
image shows a full-width-at-half-maximum of 1".2 (vs. nearby stars with FWHM
= 0".7).  Tabulated below are the discovery observations along with a single
Pan-STARRS1 position from June 4 that was identified subsequently, and three
observations obtained on June 5.4 with the 1.8-m Pan-STARRS2 Ritchey-Chretien
telescope at Haleakala.

     2018 UT             R.A. (2000) Decl.       Mag.
     June  4.52615   17 27 59.87   +28 27 29.3   19.9
           5.38409   17 27 47.86   +28 27 22.9   21.4
           5.39406   17 27 47.64   +28 27 22.9
           5.40397   17 27 47.44   +28 27 22.9   20.9
           8.50985   17 26 57.14   +28 22 56.7   21.0
           8.52162   17 26 56.92   +28 22 54.8   21.0
           8.53334   17 26 56.70   +28 22 52.9   21.0
           8.54509   17 26 56.41   +28 22 50.8   20.9

After the comet was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists also commented on the cometary appearance.  H. Sato, Tokyo,
Japan, notes that sixteen stacked 60-s exposures taken on June 12.4 with an
iTelescope 0.61-m f/6.5 astrograph at the Sierra Remote Observatory near
Auberry, CA, USA, show coma that was elongated northwards (size 4"x7"), with
no obvious tail; the w-band magnitude was 20.3 as measured within a circular
aperture of radius 3".8.  Twenty unfiltered 120-s exposures taken by E.
Bryssinck, Kruibeke, Belgium, with a 0.4-m f/3.8 Newtonian reflector on June
20.95 show a diffuse object with a central condensation and an elongated coma
of size 11"x18", elongated north-south; the magnitude was 19.7 in a
photometric aperture of radius 5".0.  Images taken by J. V. Scotti with the
Spacewatch 1.8-m f/2.7 reflector on June 22.4 in 2".2 seeing show a 6" coma
and a tail 0'.20 long in p.a. 169 degrees.
     The available astrometry (including apparently asteroidal pre-discovery
images obtained on May 19.32-19.44 with the 1.2-m Schmidt telescope at
Palomar), the following elliptical orbital elements by G. V. Williams, and an
ephemeris appear on MPEC 2018-M83.

                    Epoch = 2018 July 21.0 TT
     T = 2018 July 31.76006 TT        Peri. = 140.35638
     e = 0.6596145                    Node  = 145.21941 2000.0
     q = 1.6764108 AU                 Incl. =  26.61738
       a =  4.9250359 AU   n = 0.09017579   P =  10.93 years


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

                         (C) Copyright 2018 CBAT
2018 June 22                     (CBET 4527)              Daniel W. E. Green



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