[Iaude] CBET 5328: COMET P/2023 Y1

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5328
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/2023 Y1 (GIBBS)
     A. R. Gibbs reports his discovery of another comet on 30-s CCD exposures
obtained on Dec. 17 with the Mt. Lemmon Survey's 1.5-m reflector (discovery
observations tabulated below); in great seeing conditions, there was a
compact coma 5" across with a tail in p.a. 285 degrees that was involved with
a field star.  Four follow-up 80-s exposures taken shortly thereafter show a
condensed coma 6" across with a straight, narrow, 25" tail in p.a. 290 deg.

     2023 UT             R.A. (2000) Decl.       Mag.   Observer
     Dec. 17.50149   11 15 19.51   +12 09 13.9          Gibbs
          17.50665   11 15 19.91   +12 09 13.0   20.4     "
          17.51181   11 15 20.38   +12 09 12.2   20.7     "
          17.53335   11 15 22.00   +12 09 07.2   20.1     "
          17.53434   11 15 22.00   +12 09 06.9            "
          17.53533   11 15 22.10   +12 09 07.0            "
          17.53633   11 15 22.20   +12 09 06.6            "

After the comet was posted on the Minor Planet Center's PCCP webpage, R.
Weryk (Department of Physics and Astronomy, University of Western Ontario)
noted that four 45-s w-band survey images obtained in roughly 1".6 seeing on
Dec. 17.6 UT with the Pan-STARRS2 1.8-m Ritchey-Chretien reflector at
Haleakala show a diffuse coma of size 2".0 (full-width-at-half-maximum) with
a 5" tail in p.a. 290 degrees.  Pre-discovery apparently asteoridal
Pan-STARRS2 images were also found on Nov. 24.6 (mag 21.5-22.0).
     The available astrometry appears on MPEC 2023-Y60.  The following
elliptical orbital elements by S. Nakano (Central Bureau) are from 23
observations spanning 2023 Nov. 24-Dec. 19 (mean residual 0".4), with some
concern about the lone Nov. 24 observations.  There appear to be no close
approaches to major planets.

     T = 2023 Nov. 29.09424 TT        Peri. =  51.47507
     e = 0.4173682                    Node  =  78.33322 2000.0
     q = 2.0650734 AU                 Incl. =   6.34463
       a =  3.5443883 AU   n = 0.14770396   P =   6.67 years

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 16.0 and 2.5n = 10 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2023 12 02    10 52.81   +13 20.1    1.818    2.065    89.8    28.5  20.4
2023 12 12    11 07.83   +12 31.0    1.715    2.067    96.2    28.3  20.3
2023 12 22    11 21.00   +11 54.7    1.615    2.073   103.1    27.5  20.2
2024 01 01    11 32.01   +11 33.6    1.521    2.081   110.5    26.3  20.1
2024 01 11    11 40.49   +11 30.0    1.434    2.091   118.6    24.4  20.0
2024 01 21    11 46.07   +11 45.1    1.357    2.105   127.4    21.8  19.9
2024 01 31    11 48.51   +12 17.7    1.293    2.121   136.8    18.5  19.8
2024 02 10    11 47.73   +13 04.9    1.244    2.140   146.9    14.6  19.8
2024 02 20    11 44.00   +14 00.0    1.216    2.161   157.0    10.3  19.8
2024 03 01    11 38.07   +14 54.1    1.210    2.184   165.8     6.4  19.8
2024 03 11    11 31.00   +15 37.8    1.228    2.209   168.0     5.4  19.9
2024 03 21    11 24.10   +16 03.5    1.270    2.236   161.2     8.2  20.0
2024 03 31    11 18.56   +16 07.1    1.336    2.265   151.7    12.1  20.2
2024 04 10    11 15.13   +15 48.6    1.422    2.296   142.0    15.6  20.4
2024 04 20    11 14.24   +15 09.9    1.527    2.329   132.7    18.5  20.6
2024 04 30    11 15.87   +14 14.6    1.647    2.362   124.0    20.7  20.8
2024 05 10    11 19.82   +13 06.0    1.778    2.397   115.8    22.3  21.0


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

                         (C) Copyright 2023 CBAT
2023 December 20                 (CBET 5328)              Daniel W. E. Green