[Iaude] CBET 5077: COMET C/2021 A1

quai at eps.harvard.edu quai at eps.harvard.edu
Thu Dec 2 09:56:37 EST 2021


                                                  Electronic Telegram No. 5077
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/2021 A1 (LEONARD)
     This comet has continued to brighten roughly as predicted on CBET 4907.
K. Yoshimoto (Kumage, Yamaguchi, Japan) provides the following CCD astrometry
obtained with a 0.20-m f/8 Ritchey-Chretien reflector.  He noted the following
coma diameters and tail lengths/p.a.:  Nov. 25.8 UT, 8'.8, > 40' in p.a. 315
deg; 26.8, 10'.1, > 40' in p.a. 315 deg; 28.8, 10'.5, > 40' in p.a. 312 deg.

     2021 UT             R.A. (2000) Decl.       Mag.   Observer
     Nov. 25.81185   12 48 36.60   +32 04 09.5          Yoshimoto
          25.81858   12 48 38.46   +32 04 03.7    8.2     "
          26.84319   12 53 44.37   +31 46 44.0            "
          26.84983   12 53 46.46   +31 46 37.6    8.0     "
          28.82418   13 05 15.32   +31 04 23.0            "
          28.83091   13 05 17.90   +31 04 12.8    7.6     "

Hirohisa Sato, Sukagawa, Japan, provides the following CCD astrometry obtained
with a 0.25-m reflector:

     2021 UT             R.A. (2000) Decl.       Mag.   Observer
     Nov. 29.75559   13 11 36.11   +30 39 01.0          Sato
          29.75936   13 11 37.71   +30 38 54.6            "
          29.76314   13 11 39.36   +30 38 47.8    8.3     "

The following observations have been posted by F. Kugel, Dauban, France,
from CCD exposures taken with a 0.4-m f/2.8 reflector:

     2021 UT             R.A. (2000) Decl.       Mag.   Observer
     Dec.  1.10158   13 22 05.67   +29 53 52.6   13.0   Kugel
           1.11340   13 22 11.72   +29 53 25.2   12.6     "
           1.11433   13 22 12.13   +29 53 23.6   12.6     "
           1.11526   13 22 12.61   +29 53 21.9    8.4     "
           1.14986   13 22 30.23   +29 52 02.9   13.0     "
           1.15682   13 22 33.80   +29 51 46.7   12.8     "
           1.16469   13 22 37.77   +29 51 29.9   13.0     "
           1.17210   13 22 41.55   +29 51 12.2    8.7     "
           2.17943   13 31 51.67   +29 08 15.3   11.8     "
           2.18828   13 31 56.79   +29 07 50.5   12.4     "
           2.19280   13 31 59.44   +29 07 37.9   12.3     "
           2.19609   13 32 01.29   +29 07 28.9   12.5     "
           2.19744   13 32 02.04   +29 07 25.6   12.7     "
           2.19895   13 32 03.01   +29 07 20.2   12.2     "
           2.20045   13 32 03.88   +29 07 16.0   12.4     "
           2.20180   13 32 04.69   +29 07 12.4   12.3     "
           2.20424   13 32 06.16   +29 07 05.3   12.2     "
           2.20701   13 32 07.74   +29 06 57.6    8.8     "
           2.21298   13 32 11.14   +29 06 40.9   12.5     "
           2.21576   13 32 12.77   +29 06 33.1    9.5     "
           2.22270   13 32 16.85   +29 06 13.0   12.4     "

CCD astrometry by M. Suzuki with a 0.43-m f/4.5 telescope near Mayhill, NM:

     2021 UT             R.A. (2000) Decl.       Mag.   Observer
     Dec.  1.52058   13 25 43.81   +29 37 23.3    8.3   Suzuki
           1.52145   13 25 44.26   +29 37 21.2    8.3     "
           1.52229   13 25 44.75   +29 37 18.8    8.3     "

S. Nakano (CBAT) notes that the Crowson observations (Animas, NM, USA) and
the Mayhill observations from Nov. 29 published on MPEC 2021-W138 are bad.
The following updated orbital elements by Nakano are from 1808 observations
spanning 2020 Apr. 11-2021 Dec. 2 (mean residual 0".6), with corresponding
original and future values of 1/a being +0.000500 and -0.000105 AU**-1,
respectively (mean error +/- 0.000001 AU**-1).  There are no obvious
non-gravitational forces visible in the astrometric observations.  The comet
will pass 0.23 AU from the earth on 2021 Dec. 12.6 UT and 0.029 AU from
Venus on 2021 Dec. 18.1 UT; on the latter date, the comet will be located
5.1 deg from Venus in p.a. 217.7 degrees (geocentric location).

                    Epoch = 2022 Jan. 21.0 TT
     T = 2022 Jan.  3.29850 TT        Peri. = 225.09198
     e = 1.0000279                    Node  = 255.89560 2000.0
     q = 0.6152614 AU                 Incl. = 132.68630

     Selected total CCD magnitudes reported to the Central Bureau:  May 9.58
UT, 17.0 (K. Kadota, Ageo, Japan, 0.25-m reflector); July 16.50, 16.1
(Kadota); Sept. 19.81, 13.1 (Kadota); 23.82, 13.8, 1'.0 (K. Yoshimoto,
Yamaguchi, Japan, 0.20-m reflector; coma diameter 1'.0); Oct.  4.82, 12.5
(Kadota); 10.82, 13.3 (Hirohisa Sato, Sukagawa, Japan, 0.25-m reflector);
14.83, 11.9 (Kadota); 17.49, 13.4 (H. Sato, Tokyo, Japan, remotely with a
0.43-m astrograph near Mayhill, NM, USA; coma diameter 1'.2); 25.84, 11.1
(Yoshimoto; coma diameter 4'.1); Nov. 4.84, 10.0 (Yoshimoto, 180-mm f/2.8
lens + Canon EOS Kiss X7i digital camera; coma diameter 4'.7); 10.82, 9.4
(Kadota); 14.84, 9.1 (Yoshimoto, 0.08-m refractor + CMOS camera; coma diameter
9'.2); 16.85, 8.8 (Yoshimoto, 0.20-m reflector; coma diameter 9'.4); 19.81,
8.6 (Kadota); 25.82, 8.2 (Yoshimoto; coma diameter 8'.8); 28.83, 7.6
(Yoshimoto; coma diameter 10'.5).
     Visual total-magnitude and coma-diameter estimates:  Oct. 7.20 UT, 11.2,
5' (J. J. Gonzalez, Leon, Spain, 0.20-m reflector); Nov. 5.23, 9.7, 5'
(Gonzalez); 6.83, 9.8, 5' (K. Yoshimoto, Yamaguchi, Japan, 20x100 binoculars);
11.22, 8.7, 8' (Gonzalez, Asturias, Spain, 25x100 binoculars); 14.83, 8.7, 7'
(Yoshimoto); 18.24, 7.9, 8' (Gonzalez); 22.84, 8.4, 7' (Yoshimoto).
     The following ephemeris by the undersigned from the above orbital
elements uses photometric power-law parameters H = 8.5 and 2.5n = 10 for the
total magnitudes.  Forward scattering of dusty particles near perihelion may
cause the comet to appear brighter.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2021 11 22    12 33.31   +32 51.5    0.846    1.067    70.7    60.9   8.4
2021 11 24    12 40.70   +32 29.4    0.774    1.036    70.9    64.2   8.1
2021 11 26    12 49.49   +32 01.2    0.701    1.006    70.8    68.0   7.8
2021 11 28    13 00.15   +31 23.7    0.629    0.976    70.4    72.2   7.4
2021 11 30    13 13.36   +30 31.8    0.558    0.946    69.3    77.2   7.0
2021 12 02    13 30.12   +29 16.7    0.488    0.917    67.4    83.2   6.6
2021 12 04    13 51.87   +27 23.5    0.420    0.888    64.2    90.6   6.1
2021 12 06    14 20.66   +24 25.7    0.356    0.859    59.2   100.0   5.6
2021 12 08    14 59.04   +19 39.0    0.299    0.832    51.4   112.3   5.1
2021 12 10    15 49.15   +12 06.2    0.256    0.805    39.9   128.4   4.6
2021 12 12    16 49.92   +01 32.3    0.235    0.779    25.4   147.2   4.3
2021 12 14    17 54.38   -09 57.9    0.241    0.755    15.0   160.3   4.2
2021 12 16    18 52.73   -19 15.4    0.273    0.731    18.9   154.2   4.3
2021 12 18    19 39.32   -25 22.0    0.324    0.709    26.6   141.5   4.6
2021 12 20    20 14.12   -29 05.7    0.387    0.689    32.4   130.1   4.8
2021 12 22    20 39.52   -31 23.3    0.456    0.671    36.0   120.4   5.1
2021 12 24    20 58.02   -32 51.4    0.529    0.655    38.2   111.9   5.3
2021 12 26    21 11.55   -33 50.8    0.604    0.641    39.2   104.3   5.5
2021 12 28    21 21.45   -34 32.6    0.680    0.631    39.5    97.2   5.7
2021 12 30    21 28.67   -35 03.1    0.757    0.622    39.3    90.4   5.8
2022 01 01    21 33.88   -35 26.1    0.832    0.617    38.6    84.0   6.0

2022 01 11    21 42.71   -36 20.0    1.187    0.638    32.5    55.9   6.9
2022 01 21    21 39.84   -36 21.7    1.479    0.724    25.3    35.6   7.9
2022 01 31    21 34.94   -36 00.7    1.698    0.851    20.7    24.1   8.9
2022 02 10    21 30.50   -35 33.6    1.852    0.997    21.0    20.8   9.8
2022 02 20    21 26.59   -35 09.8    1.951    1.150    26.2    22.3  10.6
2022 03 02    21 22.70   -34 54.7    2.002    1.305    34.1    25.2  11.2
2022 03 12    21 18.06   -34 51.5    2.013    1.459    43.3    27.9  11.7
2022 03 22    21 11.83   -35 02.5    1.990    1.611    53.5    29.8  12.1
2022 04 01    21 03.10   -35 29.2    1.941    1.760    64.5    30.8  12.4
2022 04 11    20 50.72   -36 11.6    1.874    1.907    76.4    30.7  12.7
2022 04 21    20 33.42   -37 06.8    1.799    2.050    89.3    29.3  12.9
2022 05 01    20 09.96   -38 06.5    1.727    2.191   103.3    26.6  13.1
2022 05 11    19 39.57   -38 54.6    1.672    2.329   118.5    22.4  13.3
2022 05 21    19 03.00   -39 08.4    1.647    2.464   134.5    17.0  13.5
2022 05 31    18 23.17   -38 28.1    1.666    2.597   150.7    11.0  13.8
2022 06 10    17 44.60   -36 50.4    1.737    2.728   164.4     5.7  14.1
2022 06 20    17 11.31   -34 32.8    1.861    2.857   165.7     5.1  14.4
2022 06 30    16 45.09   -32 02.1    2.034    2.983   154.3     8.5  14.8
2022 07 10    16 25.91   -29 39.4    2.248    3.108   141.4    11.8  15.2
2022 07 20    16 12.73   -27 36.1    2.493    3.230   129.0    14.1  15.6
2022 07 30    16 04.33   -25 55.2    2.760    3.351   117.5    15.6  16.0
2022 08 09    15 59.66   -24 35.7    3.041    3.470   106.7    16.3  16.3


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

                         (C) Copyright 2021 CBAT
2021 December 2                  (CBET 5077)              Daniel W. E. Green



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