[Iaude] CBET 5384: COMET C/2024 G3

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5384
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 G3 (ATLAS)
     An apparently asteroidal object discovered on CCD images taken on Apr. 5
UT with a 0.5-m f/2 Schmidt reflector at Rio Hurtado, Chile, in the course of
the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program has
been found to show cometary appearance by CCD astrometrists elsewhere, after
posting on the Minor Planet Center's PCCP webpage.  The discovery observations
are tabulated below:

     2024 UT             R.A. (2000) Decl.       Mag.
     Apr.  5.26369   18 15 45.79   -74 35 25.7   19.2
           5.28177   18 15 44.96   -74 35 36.7   18.8
           5.28591   18 15 45.10   -74 35 39.2   18.7
           5.29849   18 15 44.58   -74 35 47.0   18.8
           5.30553   18 15 44.41   -74 35 51.3   18.4

K. Yoshimoto, Yamaguchi, Japan, writes that images obtained on Apr. 8.27-8.29
UT with a "Deep Sky Chile" 0.36-m f/7.2 corrected Dall-Kirkham telescope
located at Rio Hurtado, Chile, show a nearly stellar head with a faint tail 6"
long in p.a. 245 deg; the V magnitude was measured to be 19.3.  Twenty-one
300-s exposures taken remotely on Apr. 11.01-11.13 by A. Aletti, L. Buzzi, F.
Bellini, and G. Galli using a 0.36-m f/8.4 reflector located at Hakos,
Namibia, show a softer aspect (full-width-at-half-maximum 5".3) vs. nearby
stars (FWHM 3".9), with a slightly condensed 7" coma but no clear tail; the
magnitude was measured to be 18.7.  Exposures taken remotely by A. Hale
(Cloudcroft, NM, USA) on Apr. 16.03-16.04 with a Las Cumbres Observatory
0.35-m telescope at Sutherland, South Africa, show a condensed coma of size
3" with a straight 7".5 tail in p.a. 300 degrees.
     The astrometry appears on MPEC 2024-H22.  The following parabolic orbital
elements by S. Nakano (Central Bureau) are from 87 observations spanning 2024
Apr. 5-17 (mean residual 0".5).  There are no close approaches to major
planets.

     T = 2025 Jan. 13.41224 TT        Peri. = 108.14863
                                      Node  = 220.37853 2000.0
     q = 0.0935008 AU                 Incl. = 116.82222

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 03 31    18 17.19   -73 44.0    4.510    4.711    95.4    12.2  18.7
2024 04 10    18 12.81   -75 23.2    4.293    4.600   101.6    12.3  18.5
2024 04 20    17 59.72   -77 05.8    4.084    4.487   107.3    12.3  18.3
2024 04 30    17 33.54   -78 42.9    3.888    4.372   112.4    12.3  18.1
2024 05 10    16 49.29   -79 57.5    3.707    4.256   116.6    12.2  17.9
2024 05 20    15 47.53   -80 23.2    3.545    4.139   119.6    12.3  17.7
2024 05 30    14 42.23   -79 38.5    3.403    4.020   120.9    12.5  17.5
2024 06 09    13 50.87   -77 45.5    3.285    3.899   120.5    13.0  17.3
2024 06 19    13 18.33   -75 04.8    3.189    3.776   118.2    13.7  17.1
2024 06 29    13 00.55   -71 57.8    3.115    3.652   114.2    14.7  17.0
2024 07 09    12 52.70   -68 40.1    3.062    3.525   108.9    15.8  16.8
2024 07 19    12 51.38   -65 22.8    3.026    3.396   102.6    17.0  16.7
2024 07 29    12 54.42   -62 13.6    3.003    3.264    95.7    18.0  16.5
2024 08 08    13 00.51   -59 17.4    2.990    3.130    88.4    18.9  16.3
2024 08 18    13 08.84   -56 37.3    2.981    2.994    81.0    19.5  16.2
2024 08 28    13 18.87   -54 14.4    2.971    2.854    73.5    19.8  16.0
2024 09 07    13 30.30   -52 08.7    2.957    2.710    66.1    19.9  15.8
2024 09 17    13 42.91   -50 19.3    2.933    2.563    58.9    19.6  15.6
2024 09 27    13 56.57   -48 44.3    2.897    2.412    51.9    19.1  15.4
2024 10 07    14 11.25   -47 21.4    2.844    2.256    45.3    18.4  15.1
2024 10 17    14 26.94   -46 08.1    2.773    2.094    39.0    17.4  14.8
2024 10 27    14 43.70   -45 00.9    2.679    1.927    33.3    16.4  14.4
2024 11 06    15 01.69   -43 56.2    2.562    1.752    28.2    15.5  14.0
2024 11 16    15 21.10   -42 48.7    2.418    1.568    24.1    14.9  13.5
2024 11 26    15 42.35   -41 31.4    2.247    1.374    21.3    15.1  12.9
2024 12 06    16 06.10   -39 53.3    2.045    1.167    19.8    16.6  12.1
2024 12 16    16 33.63   -37 34.6    1.810    0.940    19.3    20.3  11.1
2024 12 26    17 07.76   -33 53.3    1.540    0.686    18.8    27.5   9.6
2025 01 05    17 57.18   -26 56.9    1.225    0.384    15.6    43.5   7.1
2025 01 15    20 15.47   -18 35.4    0.948    0.127     7.3   102.6   2.7
2025 01 25    21 50.41   -31 13.4    1.230    0.487    22.0    49.3   7.9
2025 02 04    22 35.98   -35 58.5    1.498    0.770    27.4    36.1  10.0
2025 02 14    23 08.79   -38 20.2    1.729    1.014    30.7    29.8  11.2


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

                         (C) Copyright 2024 CBAT
2024 April 18                    (CBET 5384)              Daniel W. E. Green