[Iaude] COMET C/2023 X1

quai at eps.harvard.edu quai at eps.harvard.edu
Mon Dec 11 21:55:33 EST 2023


                                                  Electronic Telegram No. 5322
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 X1 (LEONARD)
     G. J. Leonard, Lunar and Planetary Laboratory, University of Arizona,
reports his discovery of a comet on CCD images obtained on Dec. 4 with the
Catalina Sky Survey's 0.68-m Schmidt telescope (discovery observations
tabulated below).  The comet showed a moderately condensed coma about 8"
across with no apparent tail in four 30-s co-added images.

     2023 UT             R.A. (2000) Decl.       Mag.   Observer
     Dec.  4.44005   12 39 03.85   +18 23 33.9   17.3   Leonard
           4.44205   12 39 04.14   +18 23 43.1   17.6     "
           4.44404   12 39 04.31   +18 23 51.0   17.2     "
           4.44605   12 39 04.41   +18 23 59.6   17.7     "

After the comet was posted on the Minor Planet Center's PCCP webpage, other
CCD astrometrists also commented on the cometary appearance.  A. Hale
(Cloudcroft, NM, USA) writes that 180-s exposures taken on Dec. 5.6 UT with a
0.35-m Schmidt-Cassegrain reflector in the Las Cumbres Observatory's Clamshell
dome at Haleakala, HI, USA, show a diffuse coma of diameter 1'.2 with no
tail; he adds that a small, somewhat bright central condensation was embedded
within a larger, diffuse coma.  One-hundred-twenty-six stacked 30-s exposures
taken on Dec. 6.2 by A. Aletti (and measured with M. Auteri) using a 0.36-m
f/7.5 reflector at Varese, Italy, show it to be clearly a comet despite the
moon being nearby, with a condensed 25" coma in size (mag 18.3) and no tail.
Ten stacked 60-s exposures taken remotely by M. Mattiazzo (Swan Hill,
Victoria, Australia) with a 0.43-m f/6.8 reflector (+ luminance filter)
located at the Utah Desert Remote Observatory (near Beryl Junction, UT, USA)
on Dec. 6.47 show a diffuse coma 1' with total (UCAC4 V) magnitude 16.8,
adding that the moon was situated only 21 degrees from the comet.  Twenty-
three stacked 60-s exposures taken remotely on Dec. 6.5 by H. Sato (Bunkyo-ku,
Tokyo, Japan) with a 0.25-m f/3.4 astrograph at the Utah Desert Remote
Observatory show the comet to be moderately condensed with an outer coma 2'.0
in diameter and no tail; the magnitude was 14.7 as measured within a circular
aperture of radius 60".0.
     The astrometry appears on MPEC 2023-X225.  The following parabolic
orbital elements by S. Nakano (Central Bureau) are from 123 observations
spanning Dec. 4-11 (mean residual 0".5).  These elements indicate that the
comet passed 1.69 AU from Saturn on 2021 July 15 and 3.48 AU from Jupiter on
2021 Dec. 12 UT.

     T = 2023 Oct. 18.28550 TT        Peri. = 321.83104
                                      Node  = 137.09188 2000.0
     q = 0.9536441 AU                 Incl. = 110.62833

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.
2023 10 23    11 40.40   -15 37.1    1.656    0.957    31.3    32.7  14.4
2023 10 28    11 45.81   -12 47.7    1.610    0.969    34.4    35.4  14.4
2023 11 02    11 51.49   -09 47.0    1.557    0.988    38.1    38.3  14.4
2023 11 07    11 57.51   -06 32.2    1.497    1.014    42.3    41.1  14.4
2023 11 12    12 03.90   -02 59.9    1.432    1.047    47.0    43.7  14.4
2023 11 17    12 10.74   +00 53.9    1.365    1.085    52.0    45.9  14.5
2023 11 22    12 18.07   +05 13.8    1.297    1.128    57.3    47.5  14.5
2023 11 27    12 25.98   +10 04.6    1.230    1.175    62.9    48.4  14.5
2023 12 02    12 34.57   +15 30.6    1.168    1.225    68.7    48.6  14.5
2023 12 07    12 43.99   +21 35.0    1.114    1.278    74.7    48.1  14.6
2023 12 12    12 54.43   +28 17.7    1.070    1.333    80.8    46.8  14.6
2023 12 17    13 06.19   +35 33.9    1.040    1.390    86.7    45.0  14.7
2023 12 22    13 19.71   +43 12.6    1.026    1.449    92.2    42.7  14.8
2023 12 27    13 35.72   +50 56.8    1.031    1.508    96.9    40.3  15.0
2024 01 01    13 55.43   +58 26.8    1.056    1.569   100.5    38.0  15.2
2024 01 06    14 20.92   +65 23.3    1.099    1.630   102.9    36.0  15.4
2024 01 11    14 56.04   +71 29.5    1.158    1.691   104.0    34.3  15.6
2024 01 16    15 47.84   +76 29.8    1.233    1.753   104.0    33.0  15.9
2024 01 21    17 07.24   +80 04.0    1.320    1.815   103.0    31.9  16.2
2024 01 26    18 56.97   +81 45.9    1.416    1.878   101.4    30.9  16.4
2024 01 31    20 46.53   +81 34.5    1.520    1.940    99.2    30.1  16.7
2024 02 05    22 05.75   +80 17.0    1.630    2.002    96.8    29.3  17.0
2024 02 10    22 57.67   +78 39.5    1.744    2.064    94.1    28.5  17.2
2024 02 15    23 33.15   +77 04.0    1.860    2.126    91.3    27.7  17.5
2024 02 20    23 59.24   +75 38.3    1.979    2.188    88.5    26.8  17.7
2024 02 25    00 19.73   +74 24.5    2.097    2.250    85.6    26.0  17.9
2024 03 01    00 36.73   +73 22.5    2.216    2.311    82.8    25.2  18.1
2024 03 06    00 51.42   +72 31.6    2.334    2.372    80.0    24.3  18.3
2024 03 11    01 04.55   +71 50.8    2.451    2.433    77.3    23.5  18.5
2024 03 16    01 16.56   +71 19.0    2.566    2.494    74.6    22.6  18.7
2024 03 21    01 27.75   +70 55.3    2.679    2.554    72.1    21.8  18.9
2024 03 26    01 38.33   +70 38.8    2.789    2.615    69.6    21.0  19.1
2024 03 31    01 48.46   +70 28.7    2.896    2.674    67.3    20.2  19.2
2024 04 05    01 58.25   +70 24.3    3.000    2.734    65.1    19.4  19.4
2024 04 10    02 07.78   +70 25.2    3.100    2.793    63.1    18.6  19.5
2024 04 15    02 17.12   +70 30.8    3.197    2.852    61.2    17.9  19.7
2024 04 20    02 26.30   +70 40.6    3.290    2.911    59.4    17.3  19.8
2024 04 25    02 35.36   +70 54.3    3.379    2.969    57.9    16.7  19.9
2024 04 30    02 44.35   +71 11.5    3.464    3.027    56.5    16.1  20.0
2024 05 05    02 53.29   +71 32.0    3.545    3.085    55.3    15.6  20.2
2024 05 10    03 02.21   +71 55.5    3.622    3.142    54.3    15.1  20.3


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

                         (C) Copyright 2023 CBAT
2023 December 12                 (CBET 5322)              Daniel W. E. Green



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