[Iaude] CBET 5355: COMET C/2023 X7

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5355
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 C/2023 X7 (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 2023 Dec. 10 UT
(discovery observations tabulated below).  No activity could be discerned
then, but activity was found subsequently.

     2023 UT             R.A. (2000) Decl.       Mag.
     Dec. 10.38833    5 52 53.01   -40 52 37.0   20.4
          10.39944    5 52 52.55   -40 52 35.5   20.5
          10.41050    5 52 52.15   -40 52 34.3   20.6
          10.42158    5 52 51.71   -40 52 33.0   20.6

Weryk writes that two 60-s Pan-STARRS2 w-band follow-up images taken on
2024 Feb. 4.25 UT in 1".8-1".9 seeing show a diffuse coma of size about 2".6
(full-width-at-half-maximum) with a broad tail 3" long spanning p.a. 70-150
degrees.  Y. Ramanjooloo, Institute for Astronomy, University of Hawaii (UH),
adds that three 300-s follow-up exposures taken with the UH 2.2-m telescope
on 2024 Feb. 20.2 in 1".4-1".8 seeing show a very condensed head of size 2".2
(FWHM) with a possible faint and short tail towards the southeast.
     After the object was posted on the Minor Planet Center's PCCP webpage,
H. Sato (Bunkyo-ku, Tokyo, Japan) reported that nine stacked 120-s CCD
exposures taken with a 0.51-m f/6.8 astrograph at Siding Spring, NSW,
Australia, on 2023 Dec. 11.5 UT show only a stellar appearance; the magnitude
was 19.9 as measured within a circular aperture of radius 4".3.  Sato adds
that ten stacked 60-s CCD exposures taken with a "Deep Sky Chile" 0.51-m
f/6.8 astrograph located at Rio Hurtado, Chile, on 2024 Jan. 6.1 show a
strongly condensed coma 7" in diameter with no tail; the magnitude was 19.8
as measured within a circular aperture of radius 3".6.
     The available astrometry appears on MPEC 2024-D102.  The following
orbital elements by S. Nakano (Central Bureau) are from 69 observations
spanning 2023 Dec. 10-2024 Feb. 20 (mean residual 0".4), with corresponding
"original" and "future" values of 1/a being +0.000274 and +0.000973 (+/-
0.000055) AU**-1, respectively.  The comet will pass 2.17 AU from Jupiter on
2025 Aug. 26 UT.

                    Epoch = 2025 May   5.0 TT
     T = 2025 May  15.17903 TT        Peri. = 354.39714
     e = 1.0027811                    Node  = 119.19972 2000.0
     q = 4.8201441 AU                 Incl. =  69.07984

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 10.0 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 02 20    05 20.50   -31 34.6    5.706    5.934    98.6     9.5  20.0
2024 03 01    05 20.60   -29 35.0    5.752    5.891    93.2     9.7  20.0
2024 03 11    05 22.01   -27 34.1    5.807    5.849    87.5     9.8  20.0
2024 03 21    05 24.63   -25 34.6    5.867    5.807    81.7     9.8  20.0
2024 03 31    05 28.34   -23 38.6    5.929    5.766    75.8     9.7  20.0
2024 04 10    05 33.02   -21 47.7    5.992    5.725    69.9     9.5  20.0
2024 04 20    05 38.55   -20 03.2    6.052    5.685    64.0     9.1  19.9
2024 04 30    05 44.80   -18 26.1    6.107    5.645    58.4     8.7  19.9
2024 05 10    05 51.66   -16 56.9    6.155    5.606    53.0     8.3  19.9
2024 05 20    05 59.01   -15 36.0    6.194    5.568    48.0     7.8  19.9
2024 05 30    06 06.75   -14 23.6    6.222    5.531    43.5     7.2  19.9

2024 07 29    06 55.91   -09 59.2    6.091    5.322    37.5     6.7  19.7
2024 08 08    07 03.72   -09 40.0    6.014    5.290    41.0     7.2  19.7
2024 08 18    07 11.16   -09 26.5    5.920    5.259    45.4     7.9  19.6
2024 08 28    07 18.14   -09 17.7    5.810    5.229    50.6     8.6  19.6
2024 09 07    07 24.56   -09 12.9    5.687    5.199    56.5     9.3  19.5
2024 09 17    07 30.29   -09 11.0    5.550    5.171    63.0    10.0  19.4
2024 09 27    07 35.23   -09 10.8    5.401    5.144    69.9    10.5  19.4
2024 10 07    07 39.25   -09 10.9    5.243    5.117    77.3    11.0  19.3
2024 10 17    07 42.21   -09 09.6    5.079    5.092    85.1    11.2  19.2
2024 10 27    07 44.00   -09 05.1    4.912    5.067    93.3    11.3  19.1
2024 11 06    07 44.50   -08 55.3    4.746    5.044   101.9    11.1  19.0
2024 11 16    07 43.64   -08 37.8    4.585    5.022   110.8    10.6  18.9
2024 11 26    07 41.39   -08 10.3    4.434    5.000   120.0     9.8  18.8
2024 12 06    07 37.78   -07 30.4    4.298    4.980   129.3     8.8  18.7
2024 12 16    07 32.94   -06 36.4    4.182    4.961   138.4     7.6  18.7
2024 12 26    07 27.11   -05 27.1    4.092    4.943   146.7     6.3  18.6
2025 01 05    07 20.61   -04 02.6    4.030    4.927   153.0     5.2  18.6
2025 01 15    07 13.88   -02 24.3    4.002    4.911   155.1     4.8  18.5
2025 01 25    07 07.34   -00 34.9    4.006    4.897   152.0     5.4  18.5
2025 02 04    07 01.45   +01 22.0    4.044    4.884   145.0     6.7  18.5
2025 02 14    06 56.56   +03 22.4    4.112    4.872   136.1     8.1  18.6


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

                         (C) Copyright 2024 CBAT
2024 February 22                 (CBET 5355)              Daniel W. E. Green