[Iaude] COMET P/2023 X3

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5326
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 X3 (PANSTARRS)
     Yudish Ramanjooloo, Institute for Astronomy, University of Hawaii,
reports the discovery of another comet in images obtained on Dec. 7 with the
Pan-STARRS1 and Pan-STARRS2 1.8-m Ritchey-Chretien reflectors at Haleakala
(discovery observations tabulated below).  Three 45-s w-band Pan-STARRS2
exposures (the first three tabulated below) taken in seeing around 1".3 show
a very diffuse coma of size 2".1 (full-width-at-half-maximum) with a very
faint tail about 3" long toward p.a. 240 degrees.

     2023 UT             R.A. (2000) Decl.       Mag.
     Dec.  7.35062    4 50 53.69   +23 54 21.4   21.1
           7.36297    4 50 53.10   +23 54 21.4   21.0
           7.37545    4 50 52.47   +23 54 21.4   21.0
           7.49363    4 50 46.75   +23 54 22.1   20.9
           7.49427    4 50 46.71   +23 54 22.1   21.0

R. Weryk, Department of Physics and Astronomy, University of Western Ontario,
adds that eight 45-s Pan-STARRS2 w-band survey images taken on Dec. 10.32-
10.36 UT in variable seeing (around 1".5) show a very condensed head of size
1".9 (FWHM) with an obvious 5" tail toward p.a. 260 degrees.
     After the comet was posted to the Minor Planet Center's PCCP webpage,
other CCD astrometrists have commented on the object's appearance.  F. D.
Romanov (Yuzhno-Morskoy, Nakhodka, Russia) writes that fifteen stacked 60-s
exposures taken remotely on Dec. 9.0 UT with the 2.0-m f/10 Ritchey-Chretien
reflector (+ Sloan r' filter) at La Palma show a compact 6" coma with no
tail (magnitude near 20.7).  Twelve stacked 120-s exposures taken remotely by
H. Sato (Bunkyo-ku, Tokyo, Japan) on Dec. 10.4 with a 0.43-m f/6.8 astrograph
located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA)
show only a stellar appearance; the magnitude was 21.4 as measured within a
circular aperture of radius 3".8.
     The available astrometry appears on MPEC 2023-X269; included are pre-
discovery single-night apparently asteroidal observations from the 2.25-m Bok
telescope at Kitt Peak on Nov. 11.4 UT (observer K. Wierzchos; mag 21.3) and
from Pan-STARRS1 on Dec. 4.34-4.36 (mag 21.5-21.6) that were in the MPC's
"isolated tracklet file", as well as additional Pan-STARRS2 observations on
Oct. 22.5 (mag 21.7-22.2) and additional Pan-STARRS1 observations on Oct. 26.5
(mag 21.5-22.0).  The following two-body elliptical orbital elements by S.
Nakano (Central Bureau) are from 49 observations spanning 2023 Oct. 22-Dec. 11
(mean residual 0".2).  These indicate that the comet passed 0.26 AU from
Jupiter on 2021 July 25 UT.

     T = 2024 Apr. 22.79554 TT        Peri. =  41.01108
     e = 0.2876701                    Node  =  62.01617 2000.0
     q = 3.0286940 AU                 Incl. =   4.48439
       a =  4.2518134 AU   n = 0.11241979   P =   8.77 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.
2023 12 02    04 55.04   +23 53.5    2.138    3.120   173.9     1.9  20.6
2023 12 12    04 47.27   +23 54.5    2.127    3.108   173.9     1.9  20.6
2023 12 22    04 39.89   +23 53.5    2.146    3.097   162.1     5.6  20.6
2024 01 01    04 33.77   +23 52.0    2.192    3.087   150.6     9.0  20.6
2024 01 11    04 29.56   +23 51.9    2.262    3.077   139.5    12.0  20.7
2024 01 21    04 27.67   +23 54.7    2.353    3.068   128.9    14.5  20.8
2024 01 31    04 28.26   +24 01.3    2.461    3.060   118.9    16.4  20.8
2024 02 10    04 31.27   +24 11.8    2.580    3.053   109.4    17.7  20.9
2024 02 20    04 36.57   +24 25.6    2.707    3.047   100.6    18.6  21.0
2024 03 01    04 43.93   +24 41.9    2.838    3.042    92.2    19.0  21.1
2024 03 11    04 53.12   +24 59.4    2.970    3.037    84.3    19.0  21.2
2024 03 21    05 03.90   +25 16.7    3.102    3.034    76.8    18.6  21.3
2024 03 31    05 16.04   +25 32.6    3.230    3.031    69.7    18.0  21.4
2024 04 10    05 29.34   +25 45.9    3.353    3.029    62.8    17.1  21.5
2024 04 20    05 43.62   +25 55.4    3.469    3.029    56.3    16.0  21.6
2024 04 30    05 58.70   +26 00.2    3.577    3.029    49.9    14.7  21.6
2024 05 10    06 14.42   +25 59.6    3.677    3.030    43.8    13.3  21.7


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

                         (C) Copyright 2023 CBAT
2023 December 13                 (CBET 5326)              Daniel W. E. Green