Electronic Telegram No. 5474
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)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


COMET C/2024 V1 (BORISOV)
     Gennadii Vladimirovich Borisov, Nauchnij, Crimea, reports his discovery
of another comet on images obtained on Nov. 8 UT with a 0.50-m f/1.9
astrograph at the MARGO observatory near Nauchnij (discovery observations
tabulated below).  The object then showed a diffuse coma of diameter about 4"
and a broad tail 4"-8" long spanning p.a. 290-310 degrees; the total green
magnitude of the comet was 19.8 as measured in a circular aperture of size
0'.25.

     2024 UT             R.A. (2000) Decl.       Mag.   Observer
     Nov.  8.04936   10 54 44.76   +64 41 21.1   19.3   Borisov
           8.05997   10 54 45.66   +64 41 18.9   19.8     "
           8.07064   10 54 46.68   +64 41 16.9   19.8     "
           8.12198   10 54 51.30   +64 41 08.4   19.0     "
           8.12861   10 54 51.91   +64 41 07.3   19.5     "
           8.13527   10 54 52.47   +64 41 06.3   19.7     "

After the comet was posted on the Minor Planet Center's PCCP webpage, L. Buzzi
(Varese, Italy) reported that forty-five stacked 60-s CMO-camera images
obtained on Nov. 11.14-11.16 UT with a 0.84-m f/3.5 reflector (measured by
A. Aletti and Buzzi) show a condensed 6" coma that is elongated toward p.a.
about 330 degrees.
     The available astrometry appears on MPEC 2024-V184 and includes pre-
discovery astrometry taken by K. Sarneczky with the Piszkesteto 0.60-m
Schmidt telescope on Oct. 28.1 UT (when the comet was apparently asteroidal
in appearance and of mag 20.1-20.5), which was sent to the MPC after the
comet was posted to the PCCP.  The following parabolic orbital elements by
S. Nakano (Central Bureau) are from 45 observations spanning Oct. 28-Nov. 11
(mean residual 0".4).  There are no close approaches to any major planets.

     T = 2025 Apr.  2.91149 TT        Peri. = 167.37497
                                      Node  = 328.72632 2000.0
     q = 2.3506947 AU                 Incl. =  54.52498

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 13.5 and 2.5n = 8 for the
magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 10 17    10 12.19   +66 12.1    2.932    2.986    83.4    19.4  19.6
2024 10 27    10 33.62   +65 25.8    2.791    2.922    87.5    19.9  19.5
2024 11 06    10 51.52   +64 47.8    2.649    2.860    92.0    20.3  19.3
2024 11 16    11 05.66   +64 21.2    2.508    2.801    96.7    20.5  19.1
2024 11 26    11 15.62   +64 08.1    2.369    2.744   101.7    20.6  18.9
2024 12 06    11 20.65   +64 09.7    2.232    2.690   106.9    20.5  18.7
2024 12 16    11 19.67   +64 24.0    2.100    2.639   112.5    20.2  18.5
2024 12 26    11 11.37   +64 45.2    1.977    2.591   118.2    19.5  18.3
2025 01 05    10 54.41   +65 00.8    1.865    2.547   123.8    18.7  18.1
2025 01 15    10 28.51   +64 49.7    1.768    2.506   129.0    17.8  17.9
2025 01 25    09 55.90   +63 46.0    1.692    2.470   132.9    17.0  17.8
2025 02 04    09 21.64   +61 28.2    1.641    2.438   134.8    16.7  17.7
2025 02 14    08 51.56   +57 51.9    1.619    2.411   133.9    17.2  17.6
2025 02 24    08 29.01   +53 13.0    1.627    2.389   130.2    18.4  17.6
2025 03 06    08 14.44   +47 57.4    1.667    2.371   124.3    20.2  17.6
2025 03 16    08 06.73   +42 31.1    1.734    2.359   117.1    22.1  17.7
2025 03 26    08 04.31   +37 13.1    1.826    2.352   109.3    23.6  17.8
2025 04 05    08 05.86   +32 14.0    1.938    2.351   101.4    24.6  17.9
2025 04 15    08 10.34   +27 37.9    2.065    2.355    93.8    25.2  18.0
2025 04 25    08 16.94   +23 24.7    2.202    2.364    86.5    25.1  18.2
2025 05 05    08 25.13   +19 31.9    2.345    2.378    79.5    24.6  18.4
2025 05 15    08 34.49   +15 56.0    2.492    2.397    72.9    23.8  18.5
2025 05 25    08 44.72   +12 33.9    2.639    2.422    66.6    22.6  18.7
2025 06 04    08 55.60   +09 22.4    2.783    2.451    60.6    21.1  18.8
2025 06 14    09 06.95   +06 18.7    2.924    2.485    55.0    19.6  19.0


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

                         (C) Copyright 2024 CBAT
2024 November 13                 (CBET 5474)              Daniel W. E. Green