Electronic Telegram No. 4368
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
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Prepared using the Tamkin Foundation Computer Network


COMET P/2017 D4 (PANSTARRS)
     Eva Lilly, Richard Wainscoat, and Rob Weryk report the discovery of
another comet on images obtained with the 1.8-m Pan-STARRS1 telescope at
Haleakala on Feb. 25 (discovery observations tabulated below), the object
showing a nuclear condensation that is soft relative to adajacent stars
(with FWHM 1".4, compared to 1".1 for the stars) and a tail extending for
approximately 4" to the north.  The Pan-STARRS1 observers are listed as B.
Gibson, T. Goggia, S. Kahale, T. Lowe, A. Schultz, and M. Willman.

     2017 UT             R.A. (2000) Decl.       Mag.
     Feb. 25.43687   10 26 36.90   - 5 52 23.5   20.6
          25.44929   10 26 36.43   - 5 52 21.6   20.8
          25.46170   10 26 35.97   - 5 52 19.8   20.7
          25.47410   10 26 35.51   - 5 52 17.9   20.7

Weryk adds that Pan-STARRS1 i-band exposures taken on Jan. 20.6 UT show an
apparent tail 3" long toward the north (with magnitude 20.9-21.1), and w-band
exposures taken on Jan. 29.6 show an apparent tail 4" to the north (with mag
21.0).  Wainscoat and D. Woodworth obtained three 90-s w-band exposures of
on Feb. 27.55 with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea,
tracked non-sidereally using the predicted motion of the comet, which showed
a nuclear condensation (FWHM 1".25, vs. 0".75 for nearby stars) and a broad
tail extending for 6" to the north (measured by M. Micheli and Wainscoat).
     After the object was posted on the Minor Planet Center's PCCP webpage,
H. Sato (Tokyo, Japan) reported that eleven stacked 60-s exposures taken
on Feb. 27.57 UT with an iTelescope 0.43-m f/6.8 astrograph (+ luminance
filter) at Siding Spring show a strongly condensed coma 6" in diameter
with no tail; the w-band magnitude was 20.0 as measured within a circular
aperture of radius 3".7.
     The available astrometry (spanning Jan. 20-Feb. 28), the following
elliptical orbital elements by G. V. Williams, and an ephemeris appear on
MPEC 2017-E07.

                    Epoch = 2016 Sept. 9.0 TT
     T = 2016 Sept. 6.51985 TT        Peri. = 209.74184
     e = 0.6289590                    Node  = 266.11097 2000.0
     q = 2.7536698 AU                 Incl. =  10.33994
       a =  7.4214697 AU   n = 0.04874939   P =  20.22 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 4368)              Daniel W. E. Green