Electronic Telegram No. 5485
Central Bureau for Astronomical Telegrams
Mailing address:  Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
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Prepared using the Tamkin Foundation Computer Network


COMET P/2024 X3 (PANSTARRS)
     R. Weryk, Department of Physics and Astronomy, University of Western
Ontario, reports the discovery of another comet in images obtained with the
Pan-STARRS2 1.8-m Ritchey-Chretien reflector at Haleakala on Dec. 8 (discovery
observations tabulated below).  Three 45-s w-band survey images taken in
1".3-1".4 seeing show a condensed coma of size 2".2 (full-width-at-half-
maximum) with a straight tail 6" long in p.a. 290 degrees.

     2024 UT             R.A. (2000) Decl.       Mag.
     Dec.  8.57146   10 25 18.30   +11 09 06.4   21.0
           8.58428   10 25 18.85   +11 09 04.3   20.7
           8.59706   10 25 19.39   +11 09 02.1   21.5

Weryk adds that four 45-s w-band Pan-STARRS2 survey images taken in 1".2-1".4
seeing on Dec. 25.5 UT show this to be clearly a comet, with stacked images
showing a condensed coma of size 1".8 (FWHM) and a straight tail 7" long in
p.a. 300 degrees.  Weryk also identified three earlier single-night sets of
observations in the Minor Planet Center's "isolated tracklet file":  from
Oct. 22.5 (at mag 20.6-20.9) and Dec. 1.5 (mag 20.6-20.9) with the 2.25-m Bok
reflector at Kitt Peak, and on Nov. 14.5 (at mag 20.3) with the 1.5-m Mt.
Lemmon reflector.  After the comet was posted on the MPC's PCCP webpage, H.
Sato (Bunkyo-ku, Tokyo, Japan) stacked sixteen 60-s CCD exposures taken
remotely on Dec. 10.55 UT with a 0.43-m f/6.8 astrograph located at the Utah
Desert Remote Observatory (near Beryl Junction, UT, USA) to find only a
stellar appearance; the magnitude was 20.6 as measured within a circular
aperture of radius 3".8.  The available astrometry appears on MPEC 2024-Y145.
     The following orbital elements by S. Nakano (Central Bureau) are from 36
observations spanning 2024 Oct. 22-Dec. 25 (mean residual 0".5).  There
are no close approaches to major planets.

     T = 2024 Sept. 5.77794 TT        Peri. = 352.94391
     e = 0.6237783                    Node  = 113.35696 2000.0
     q = 2.6131967 AU                 Incl. =   2.97221
       a =  6.9458949 AU   n = 0.05384083   P =  18.31 years

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 15.0 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 12 16    10 30.06   +10 52.3    2.264    2.746   109.0    19.8  20.3
2024 12 26    10 34.56   +10 41.0    2.171    2.773   118.1    18.2  20.2
2025 01 05    10 36.74   +10 43.8    2.089    2.801   127.8    16.1  20.2
2025 01 15    10 36.59   +11 00.4    2.022    2.832   138.1    13.4  20.1
2025 01 25    10 34.26   +11 29.3    1.975    2.864   148.9    10.2  20.1
2025 02 04    10 30.10   +12 07.4    1.951    2.898   160.2     6.6  20.1
2025 02 14    10 24.72   +12 49.9    1.953    2.933   171.5     2.9  20.2
2025 02 24    10 18.89   +13 31.6    1.983    2.970   175.4     1.5  20.3
2025 03 06    10 13.41   +14 07.8    2.041    3.009   164.6     5.0  20.4
2025 03 16    10 09.02   +14 34.7    2.126    3.049   153.6     8.3  20.5
2025 03 26    10 06.19   +14 50.2    2.235    3.090   143.0    11.2  20.7
2025 04 05    10 05.23   +14 53.7    2.364    3.132   132.9    13.5  20.8
2025 04 15    10 06.19   +14 45.5    2.511    3.176   123.4    15.3  21.0
2025 04 25    10 08.97   +14 26.6    2.672    3.220   114.4    16.5  21.2
2025 05 05    10 13.41   +13 58.0    2.843    3.265   105.8    17.3  21.4
2025 05 15    10 19.28   +13 21.0    3.020    3.311    97.7    17.6  21.6
2025 05 25    10 26.36   +12 36.6    3.202    3.358    90.0    17.6  21.7
2025 06 04    10 34.45   +11 45.8    3.385    3.406    82.6    17.2  21.9
2025 06 14    10 43.35   +10 49.6    3.567    3.454    75.4    16.5  22.1


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

                         (C) Copyright 2024 CBAT
2024 December 28                 (CBET 5485)              Daniel W. E. Green