[Iaude] CBET 4430: 20170922 : COMET P/2017 R1 (PANSTARRS)

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Sep 22 11:25:40 EDT 2017


                                                  Electronic Telegram No. 4430
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 P/2017 R1 (PANSTARRS)
     Rob Weryk, Institute for Astronomy, University of Hawaii, writes that he
and E. Lilly have noticed that an object found on four w-band exposures taken
with the 1.8-m Pan-STARRS1 telescope at Haleakala on Sept. 14.4 UT (discovery
astrometry tabulated below, together with earlier Pan-STARRS1 observations
found subsequently) appears to have a very obvious tail extending for 8"
towards the southwest; the head of the comet shows a full-width-at-half-
maximum of about 1".5, compared to 0".9 for nearby stars.

     2017 UT             R.A. (2000) Decl.       Mag.
     July 30.49462   23 42 52.69   - 2 59 55.9   21.5
          30.50666   23 42 52.60   - 2 59 57.1   21.2
          30.51860   23 42 52.49   - 2 59 58.3   21.4
          30.53051   23 42 52.40   - 2 59 59.5   21.9
     Aug.  1.53132   23 42 36.24   - 3 03 32.0   22.3
           1.54321   23 42 36.11   - 3 03 33.0   22.5
           1.55510   23 42 35.97   - 3 03 34.5   22.0
           1.56701   23 42 35.86   - 3 03 35.9   22.3
           3.52513   23 42 15.90   - 3 07 30.7   21.2
           3.53589   23 42 15.76   - 3 07 32.2   21.4
           3.54668   23 42 15.64   - 3 07 33.4   21.1
           3.55743   23 42 15.50   - 3 07 34.6   21.3
          17.47615   23 38 03.57   - 3 47 07.7   21.6
          17.48721   23 38 03.27   - 3 47 09.8   21.9
          17.49826   23 38 02.99   - 3 47 12.4   21.7
          17.50933   23 38 02.70   - 3 47 14.7   21.7
     Sept.14.40860   23 22 54.11   - 5 45 26.0   21.2
          14.42057   23 22 53.65   - 5 45 29.3   21.4
          14.43251   23 22 53.22   - 5 45 32.6   21.1
          14.44444   23 22 52.77   - 5 45 35.8   21.3

M. Micheli and R. J. Wainscoat report that the cometary nature has been
confirmed on three 60-s gri-filtered CCD images taken by Wainscoat and C.
Crowder with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea on Sept.
15.38 UT, with a broad tail about 10" long seen in p.a. about 245 degrees;
the coma had FWHM = 1".1 in 0".85 seeing.
     After the object was posted on the Minor Planet Center's PCCP webpage,
H. Sato, Tokyo, Japan, notes that sixteen stacked 60-s exposures taken on
Sept. 15.55-15.56 UT with a 0.51-m f/6.8 astrograph at Siding Spring
Observatory shows the comet to be strongly condensed with a coma 8" in
diameter and a 15" tail toward p.a. 285 degrees; the total w-band magnitude
was 19.9 as measured within a circular aperture of radius 4".9.
     The available astrometry, the following elliptical orbital elements by
G. V. Williams (from 56 observations spanning July 30-Sept. 19; mean residual
0".4), and an ephemeris appear on MPEC 2017-S97.

                    Epoch = 2017 Apr.  3.0 TT
     T = 2017 Apr.  8.8343 TT         Peri. = 178.4965
     e = 0.194222                     Node  = 143.6555  2000.0
     q = 3.328089 AU                  Incl. =   2.5736
       a =  4.130282 AU    n = 0.1174179    P =   8.39 years


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

                         (C) Copyright 2017 CBAT
2017 September 22                (CBET 4430)              Daniel W. E. Green




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