[Iaude] CBET 4445: 20171025 : COMET C/2017 T2 (PANSTARRS)

quai at eps.harvard.edu quai at eps.harvard.edu
Tue Oct 24 20:20:09 EDT 2017


                                                  Electronic Telegram No. 4445
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/2017 T2 (PANSTARRS)
     An object (with only marginal cometary appearance that was not initially
noticed) that was discovered on CCD exposures taken with the 1.8-m Pan-STARRS1
telescope at Haleakala on Oct. 2 and 10 UT (discovery astrometry tabulated
below, together with earlier Pan-STARRS1 observations found subsequently) was
found later to show cometary appearance.  After the object was moved to the
Minor Planet Center's PCCP webpage (following initial posting on its NEOCP
webpage), R. Weryk (Institute for Astronomy, University of Hawaii) reported
that neither the Oct. 2 nor the Oct. 10 images indicate a tail present, but
the full-width-at-half-maximum of the comet's image is 1".7 (in 1".0 and 1".3
seeing, respectively).  There appears to be no cometary activity visible in
the Sept. 15 images, which were taken in poor seeing (about 2".2).

     2017 UT             R.A. (2000) Decl.       Mag.
     Sept.15.58688    3 36 21.45   -14 57 56.4   20.3
          15.59883    3 36 21.32   -14 57 58.3   20.2
          15.61079    3 36 21.21   -14 58 00.3   20.2
          15.62277    3 36 21.09   -14 58 02.3   20.3
     Oct.  2.52110    3 32 39.34   -15 43 31.4   19.9
           2.53268    3 32 39.15   -15 43 33.3   19.8
           2.54430    3 32 38.94   -15 43 35.0   19.9
           2.55589    3 32 38.75   -15 43 36.9   19.8
          10.53922    3 30 12.02   -16 03 19.8   19.7
          10.55237    3 30 11.74   -16 03 21.6   19.7
          10.56555    3 30 11.49   -16 03 23.4   19.6
          10.57869    3 30 11.21   -16 03 25.3   19.6

After the object was initially posted on the Minor Planet Center's NEOCP
webpage, H. Sato (Tokyo, Japan) wrote that ten stacked 60-s CCD exposures
taken on Oct. 12.57 UT with an iTelescope 0.51-m f/6.8 astrograph at Siding
Spring, NSW, show a strongly condensed coma 6" in diameter with no tail; the
total w-band magnitude was 19.3 as measured within a circular aperture of
radius 4".9.  R. J. Wainscoat examined the object on five 60-s w-band
exposures taken on Oct. 21.52-21.53 with the 3.6-m Canada-France-Hawaii
Telescope at Mauna Kea (queue observer D. Woodworth), which show the comet
to be extended (FWHM = 1".3 in 0".75 seeing); in each image, the object
appeared to be slightly asymmetric, with a very faint low-surface-brightness
extension to the northwest (and the magnitude was measured by M. Micheli to
be 19.4-19.6).  Weryk adds that additional Pan-STARRS1 images taken on Oct.
22.5 show a very short tail extending about 0".5 towards the northwest.
J.-F. Soulier obtained 120 sixty-second unfiltered CCD exposures with a
0.20-m f/4 Newtonian reflector at the Observatoire Chante-Perdrix near
Dauban, France, on Oct. 16.04-16.11, which show a coma around 12" in size
and a tail about 20" long in p.a. 290 deg; he measured red mag 19.5 in an
aperture of radius 6".6.
     The available astrometry, the following elliptical orbital elements by
G. V. Williams (from 80 observations spanning 2017 Sept. 15-Oct. 24), and
an ephemeris appear on MPEC 2017-U180.

                    Epoch = 2020 Apr. 21.0 TT
     T = 2020 May   6.2327 TT         Peri. =  93.0213
     e = 0.998351                     Node  =  64.4048  2000.0
     q = 1.617173 AU                  Incl. =  57.2002


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

                         (C) Copyright 2017 CBAT
2017 October 25                  (CBET 4445)              Daniel W. E. Green



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