[Iaude] CBET 4449: 20171028 : COMET C/2017 T3 (ATLAS)

quai at eps.harvard.edu quai at eps.harvard.edu
Fri Oct 27 22:23:23 EDT 2017

                                                  Electronic Telegram No. 4449
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

     A moving object presumed to be asteroidal in appearance that was found
on CCD exposures taken on Oct. 14.4 UT with the ATLAS 0.5-m f/2.0 Schmidt
telescope at Haleakala in the course of the "Asteroid Terrestrial-impact Last
Alert System" (ATLAS) search program has been found to show cometary
apperance after it was posted on the Minor Planet Center's PCCP webpage.
H. Weiland, University of Hawaii, reported on Oct. 19 that six o-band ATLAS
images taken on Oct. 14.4 show a size of 3".3 vs. stellar point-spread-
function sizes of 2".3, with a possible elongation toward p.a. 310 deg.

     2017 UT             R.A. (2000) Decl.       Mag.
     Oct. 14.35217   21 43 31.92   +81 00 46.7   18.3
          14.35446   21 43 31.45   +81 00 45.6   18.4
          14.37036   21 43 29.49   +81 00 33.5   18.5
          14.37219   21 43 29.24   +81 00 32.4   18.7

H. Sato, Tokyo, Japan, writes that eight stacked 60-s exposures taken on
Oct. 18.16 UT with a 0.43-m f/6.8 astrograph near Mayhill, NM, USA, show a
strongly condensed coma 15" in diameter with a 60" tail toward p.a. 155
degrees; the total w-band magnitude was 17.7-18.1 as measured within a
circular aperture of radius 7".6.  K. Sarneczky, Konkoly Observatory, finds
that six stacked 120-s unfiltered CCD images taken with the 0.60-m Schmidt
telescope at Piszkesteto, Hungary, on Oct. 18.7 show a condensed coma 8" in
diameter with a 15" tail toward p.a. 135 degrees.  Fifteen co-added 60-s
exposures taken on Oct. 21.04-21.05 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. 131 deg; the red magnitude was measured to be 18.0-18.1.
E. Bryssinck, Kruibeke, Belgium, reports that four 180-s exposures taken
on Oct. 23.09 with an iTelescope 0.51-m f/4.5 reflector (+ luminance filter)
near Mayhill, NM, USA, show a starlike object with a hint of a coma 12" in
diameter with magnitude R = 17.9 in an aperture of radius 5".  F. Kugel writes
that Cousins V images taken by O. Mousis, J. Balcaen, and himself on Oct.
24.8 with a 1.2-m f/6 reflector at Haute Provence yield magnitude 18.8-19.4
in an aperture of radius 1".9; Cousins R-band images taken on Oct. 25.73-
25.78 show a tail about 10" long towards p.a. about 130 degrees, with a
measured coma diameter of 7" and magnitude 18.5-18.8 as measured in an
aperture of radius 1".9.  Images taken by C. Rinner and Kugel with a 0.4-m
f/3 reflector at Dauban, France, on Oct. 25.8 show a tail 10" long in p.a.
130 deg and a coma diameter around 18", with a measured magnitude 17.6-17.7
in an aperture of radius 6".4.  Ten stacked 120-s exposures taken on Oct.
26.2 with a McDonald Observatory 0.4-m f/8 reflector by P. Miller, E. Gomez,
S. Foglia, L. Buzzi, and R. Holmes reveal a coma 9" in diameter and a wide,
20"-long tail in p.a. 140 deg.
     The available astrometry (including a pre-discovery observation from
the 1.8-m Pan-STARRS1 telescope at Haleakala on Sept. 11.56 UT, when the
magnitude was measured to be 19.3), the following nearly parabolic orbital
elements by G. V. Williams (from 128 observations spanning Sept. 11-Oct.
27), and an ephemeris appear on MPEC 2017-U238.

                    Epoch = 2018 July 21.0 TT
     T = 2018 July 19.1413 TT         Peri. = 246.8875
     e = 0.999295                     Node  = 230.0961  2000.0
     q = 0.825409 AU                  Incl. =  88.1012

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 4449)              Daniel W. E. Green

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