Electronic Telegram No. 4365
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 P/2017 D1 (FULS)
     D. C. Fuls reports the discovery of a comet on CCD images taken on Feb.
21 with the Mount Lemmon 1.5-m reflector (discovery observations tabulated
below), the object showing a nuclear condensation of size about 3" with a
tail extending another 15" toward p.a. 270 degrees.

     2017 UT             R.A. (2000) Decl.       Mag.   Observer
     Feb. 21.35095   10 20 46.95   +39 10 12.6   19.8     "
          21.36505   10 20 46.36   +39 10 16.3   20.2     "
          21.37920   10 20 45.68   +39 10 19.7   20.8     "
          21.39343   10 20 45.03   +39 10 23.4   20.6     "
          21.46740   10 20 41.65   +39 10 40.6            "
          21.48167   10 20 40.90   +39 10 44.8   21.1     "
          21.51027   10 20 39.39   +39 10 51.9   19.7     "

Four co-added 150-s follow-up CCD exposures taken by A. R. Gibbs with the
Steward Observatory 1.0-m reflector at Mount Lemmon on Feb. 22.3 UT in average
transparency and seeing show a nearly stellar compact coma with a 10" tail
spanning 10 degrees toward p.a. 260 deg.
     Deliberate searches by R. Weryk of images obtained with the 1.8-m
Pan-STARRS1 telescope at Haleakala then yielded many apparently asteroidal
pre-discovery images spanning 2015 Sept. 8-2016 Mar. 6, and additional
apparently asteroidal pre-discovery observations were identified by G. V.
Williams, Minor Planet Center, from Mount Lemmon images taken on 2016 Nov. 5
(when the comet's magnitude was measured as 19.9-20.2).  The Pan-STARRS1
pre-discovery magnitudes in 2015-2016 ranged from 21.5 to 23.0.
     The available astrometry, the following elliptical orbital elements by
Williams, and an ephemeris appear on MPEC 2017-E04.

                    Epoch = 2016 June 21.0 TT
     T = 2016 June 28.28412 TT        Peri. =   7.25509
     e = 0.4403443                    Node  =  82.33543 2000.0
     q = 2.6877904 AU                 Incl. =  20.73248
       a =  4.8025785 AU   n = 0.09364668   P =  10.5 years


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2017 CBAT
2017 March 1                     (CBET 4365)              Daniel W. E. Green