[Iaude] CBET 5344: COMET C/2024 B1

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5344
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/2024 B1 (LEMMON)
     An apparently asteroidal object discovered on Jan. 16 with the Mt. Lemmon
Survey's 1.5-m reflector in Arizona has been found to show cometary appearance
after posting on the Minor Planet Center's PCCP webpage.  The discovery
observations are tabulated below.

     2024 UT             R.A. (2000) Decl.       Mag.
     Jan. 16.17491    3 54 33.40   -12 59 26.6   20.6
          16.18055    3 54 33.09   -12 59 22.1   20.7
          16.18618    3 54 32.89   -12 59 17.0   21.4
          16.19182    3 54 32.57   -12 59 12.0   20.9

R. Weryk (Department of Physics and Astronomy, University of Western Ontario)
writes that he found this object in pre-discovery exposures taken with both
the Pan-STARRS1 and the Pan-STARRS2 1.8-m Ritchey-Chretien reflectors at
Haleakala, spanning back to 2023 Oct. 13.6 UT, when Pan-STARRS1 images showed
it at mag 22.5-22.8.  Other Pan-STARRS1 images were found from 2023 Dec. 5.4
(mag 20.4-20.7), 9.4 (mag 21.1-22.0), and 15.4 (mag 20.2-20.8), as well as on
2024 Jan. 3.3 (mag 20.3-20.6).  The four 45-s w-band survey images taken on
Dec. 15.4 show seeing around 1".6 show a condensed, somewhat soft object of
size around 2" (full-width-at-half-maximum) and no tail.  Weryk also found
images in Pan-STARRS2 exposures taken on 2023 Oct. 19.54-19.57 (mag 21.8-23),
2023 Oct. 23.6 (mag 22.4-23.7), 2023 Nov. 20.45-20.47 (mag 21.5-21.8), and
2023 Dec. 24.32-24.36 (mag 21.6-21.7).
     Twenty stacked 60-s CCD exposures taken remotely by H. Sato (Bunkyo-ku,
Tokyo, Japan) with a "Deep Sky Chile" 0.51-m f/6.8 astrograph located at Rio
Hurtado, Chile, on 2024 Jan. 31.05 UT show a strongly condensed coma 7" in
diameter with no tail; the magnitude was 20.6 as measured within a circular
aperture of radius 3".6.  Two-hundred-forty 30-s CCD exposures taken by A.
Aletti with a 0.36-m f/7.5 reflector at Varese, Italy, on 2024 Feb. 8.83-1.87
(and measured by Aletti and M. Auteri) show a slightly condensed coma 5" wide
and of mag 20.5 that was extended toward the west.
     The astrometry appears on MPEC 2024-C86.  The following nearly parabolic
orbital elements by S. Nakano (Central Bureau) are from 53 observations
spanning 2023 Oct. 13-2024 Feb. 2 (mean residual 0".4), with corresponding
"original" and "future" values of 1/a being +0.000089 and -0.000463 (+/-
0.000019) AU**-1, respectively.  These indicate that the comet will pass 2.65
AU from Jupiter on 2024 Mar. 20 UT.

                    Epoch = 2024 Oct. 17.0 TT
     T = 2024 Oct.  7.71120 TT        Peri. =  66.21223
     e = 1.0007420                    Node  =  79.18809 2000.0
     q = 1.6336364 AU                 Incl. =  70.90424

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 13.0 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 01 11    03 58.71   -14 11.8    3.105    3.666   117.6    13.7  20.0
2024 01 21    03 51.18   -11 48.5    3.128    3.572   109.0    15.1  19.9
2024 01 31    03 45.77   -09 13.9    3.166    3.477   100.1    16.2  19.8
2024 02 10    03 42.56   -06 32.6    3.216    3.381    91.1    17.0  19.8
2024 02 20    03 41.50   -03 48.4    3.271    3.286    82.2    17.3  19.7
2024 03 01    03 42.44   -01 04.0    3.327    3.191    73.6    17.3  19.6
2024 03 11    03 45.24   +01 38.9    3.379    3.096    65.2    16.9  19.6
2024 03 21    03 49.72   +04 19.5    3.424    3.001    57.0    16.2  19.5
2024 03 31    03 55.72   +06 57.2    3.459    2.906    49.2    15.1  19.4

2024 09 07    09 25.72   +48 24.0    2.201    1.685    47.1    26.0  16.5
2024 09 17    10 19.10   +49 40.5    2.107    1.657    50.3    27.8  16.4
2024 09 27    11 17.06   +49 44.8    2.038    1.640    52.8    29.1  16.3
2024 10 07    12 15.70   +48 25.2    1.998    1.634    54.4    29.9  16.2
2024 10 17    13 10.72   +45 48.3    1.989    1.638    55.2    30.0  16.2
2024 10 27    13 59.44   +42 16.6    2.009    1.654    55.1    29.5  16.3
2024 11 06    14 41.18   +38 18.5    2.054    1.680    54.3    28.6  16.4
2024 11 16    15 16.53   +34 18.5    2.118    1.716    53.1    27.4  16.5
2024 11 26    15 46.55   +30 33.0    2.194    1.762    51.7    26.1  16.7
2024 12 06    16 12.25   +27 11.3    2.274    1.815    50.5    24.8  16.9
2024 12 16    16 34.44   +24 16.9    2.354    1.875    49.8    23.6  17.0
2024 12 26    16 53.72   +21 50.0    2.427    1.942    49.7    22.7  17.2
2025 01 05    17 10.52   +19 49.3    2.490    2.014    50.6    22.2  17.4
2025 01 15    17 25.08   +18 12.2    2.539    2.091    52.5    21.9  17.6
2025 01 25    17 37.56   +16 55.8    2.574    2.172    55.4    21.9  17.7
2025 02 04    17 48.01   +15 57.5    2.592    2.255    59.4    22.1  17.9
2025 02 14    17 56.39   +15 14.2    2.594    2.342    64.3    22.3  18.0


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

                         (C) Copyright 2024 CBAT
2024 February 8                  (CBET 5344)              Daniel W. E. Green