[Iaude] CBET 4446: 20171028 : COMET P/2017 S8 (PANSTARRS)

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Oct 27 20:59:31 EDT 2017

                                                  Electronic Telegram No. 4446
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

     R. Weryk, Institute for Astronomy, University of Hawaii, reports the
discovery of another comet on CCD exposures taken with the 1.8-m Pan-STARRS1
telescope at Haleakala on Sept. 30 UT (discovery astrometry tabulated below),
to object showing a very noticeable 8" tail towards the west; the comet's
head showed a full-width-at-half-maximum of about 2".0 in 1".3 seeing.

     2017 UT             R.A. (2000) Decl.       Mag.
     Sep. 30.54189    3 06 51.70   + 1 51 46.8   20.2
          30.55263    3 06 51.86   + 1 51 29.1   20.3
          30.56337    3 06 52.04   + 1 51 10.7   20.6

R. J. Wainscoat and Weryk report that three 60-s CCD exposures obtained by
Wainscoat and C. Wipper on Oct. 22.46 UT with the 3.6-m Canada-France-Hawaii
Telescope (+ w-band filter) at Mauna Kea (measured with M. Micheli) show a
bright, sharp tail about 60" long in p.a. 295 deg with a possible much-
shorter anti-tail to the east.
     After the comet was posted on the Minor Planet Center's PCCP webpage,
other CCD astrometrists also reported cometary appearance.  H. Sato, Tokyo,
Japan, obtained eight stacked 60-s exposures with an iTelescope 0.61-m f/6.5
astrograph at the Sierra Remote Observatory near Auberry, CA, USA, on Oct.
2.53 UT that show a moderately condensed coma 8" in diameter with a 20" tail
toward p.a. 265 degrees; the total w-band magnitude was 19.5 as measured
within a circular aperture of radius 5".0.  A. F. Tubbiolo obtained 55-s
exposures with the Steward Observatory 0.9-m f/3 reflector at Kitt Peak on
Oct. 12.4 in 1".5 seeing that show a tail extending about 15" in p.a.
approximately 175 deg.  K. Sarneczky, Konkoly Observatory, writes that nine
stacked 90-s unfiltered CCD images taken with the 1.02-m Ritchey-Chretien
telescope at Piszkesteto, Hungary, on Oct. 14.0 show a nearly stellar coma
and a slighly curved tail about 15" long in p.a. about 280 deg; the red
magnitude of the coma was 19.2 as measured within a circular aperture of
radius 3".0.  Forty-eight co-added 30-s exposures taken by P. Bacci and M.
Maestripieri (and measured by Bacci with L. Tesi and G. Fagioli) with a
0.60-m f/4 reflector at San Marcello Pistoiese, Italy, apparently show a
diffuse coma and 16" tail in p.a. 300 deg.  R. A. Mastaler finds a tail in
p.a. approximately 290 degrees on four stacked 90-s exposures taken on
Oct. 21.3 with the Spacewatch II 1.8-m f/2.7 reflector; a nearby bright star
prevented determination of the tail length.  Eight stacked 120-s exposures
taken by E. Bryssinck (Kruibeke, Belgium) with an iTelescope 0.51-m f/4.5
reflector near Mayhill, NM, USA, on Oct. 25.36 show a condensed, starlike
appearance and an elongated shape of size 8" x 12" toward the west (p.a.
276 deg); the magnitude was R = 19.0.  Four co-added 30-s exposures taken
by G. J. Leonard with the Mount Lemmon 1.5-m reflector on Oct. 26.3 show a
narrow tail 15" long in p.a. 295 deg.  D. C. Fuls notes that images taken on
Oct. 26.36 with the Steward Observatory 1.0-m reflector at Mount Lemmon
show a clear tail in p.a. 290 deg.
     The available astrometry (including apparently asteroidal pre-discovery
images taken on Sept. 25.4 and 29.4 UT in the course of the Catalina Sky
Survey, when the measured magnitudes were 19.4-19.8 and 19.5-19.7,
respectively), the following elliptical orbital elements by G. V. Williams
(from 143 observations spanning Sept. 25-Oct. 27), and an ephemeris appear
on MPEC 2017-U236.

                    Epoch = 2018 Feb. 11.0 TT
     T = 2018 Jan. 28.6442 TT         Peri. = 254.5465
     e = 0.393906                     Node  = 191.8146  2000.0
     q = 1.683420 AU                  Incl. =  29.8705
       a =  2.777491 AU    n = 0.2129243    P =   4.63 years

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

                         (C) Copyright 2017 CBAT
2017 October 28                  (CBET 4446)              Daniel W. E. Green

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