[Iaude] CBET 5397: COMET C/2024 G7

[quai at eps.harvard.edu]

                                                  Electronic Telegram No. 5397
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 G7 (ATLAS)
     An apparently asteroidal object discovered on CCD images taken on Apr. 3
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
the object was posted to the Minor Planet Center's PCCP webpage.  The
discovery observations are tabulated below:

     2024 UT             R.A. (2000) Decl.       Mag.
     Apr.  3.34729   22 07 44.95   -61 32 18.8   19.4
           3.37231   22 07 45.75   -61 32 28.8   19.4
           3.37508   22 07 45.79   -61 32 31.1   19.2
           3.39451   22 07 46.29   -61 32 39.2   19.4
           6.33363   22 09 00.30   -61 52 48.5   19.5
           6.34336   22 09 00.70   -61 52 52.5   19.0
           6.34613   22 09 00.68   -61 52 54.6   19.4
           6.35591   22 09 00.88   -61 52 58.1   19.2
           6.35868   22 09 00.93   -61 52 59.8   17.9
           6.41272   22 09 02.29   -61 53 23.9   19.2

Eight stacked 60-s exposures taken remotely on Apr. 7.4 UT by H. Sato
(Bunkyo-ku, Tokyo, Japan) with a "Deep Sky Chile" 0.51-m f/6.8 astrograph
located at Rio Hurtado, Chile, show a moderately condensed coma 7" in diameter
with no tail; the magnitude was 19.1 as measured within a circular aperture of
radius 3".6.  Eight stacked 60-s follow-up exposures taken by Sato on May 7.8
with a 0.51-m f/6.8 astrograph located at Siding Spring, NSW, Australia,
again show a strongly condensed coma 7" in diameter and no tail; the magnitude
was 18.6 as measured within a circular aperture of radius 6".6.  Exposures
taken on Apr. 21.8 by T. Prystavski (Lviv, Ukraine) using a 0.51-m f/4
Corrected Dall-Kirkham telescope at Siding Spring show a coma of size 10".8
with total mag 19.2, with an apparently elongation toward p.a. 82 degrees.
     The available astrometry appears on MPEC 2024-K41.  The following
parabolic orbital elements are from 45 observations spanning Apr. 3-May 11
(mean residual 0".4).  The comet passed 1.95 AU from Uranus in 2015 October.

     T = 2025 Feb.  9.05670 TT        Peri. = 289.50338
                                      Node  = 191.92206 2000.0
     q = 6.0322610 AU                 Incl. = 131.51635

The following ephemeris by the undersigned from the above orbital elements
uses photometric power-law parameters H = 8.5 and 2.5n = 8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2024 05 10    22 14.35   -67 06.1    6.077    6.330   100.0     9.0  18.8
2024 05 20    22 10.72   -69 05.5    5.946    6.309   106.6     8.8  18.8
2024 05 30    22 02.88   -71 12.7    5.830    6.289   112.6     8.6  18.7
2024 06 09    21 49.04   -73 22.6    5.735    6.270   117.6     8.2  18.7
2024 06 19    21 26.75   -75 27.1    5.663    6.252   121.3     8.0  18.6
2024 06 29    20 53.32   -77 14.5    5.616    6.234   123.4     7.8  18.6
2024 07 09    20 07.46   -78 29.5    5.597    6.217   123.5     7.8  18.6
2024 07 19    19 13.03   -78 57.5    5.606    6.200   121.7     8.0  18.6
2024 07 29    18 19.65   -78 34.1    5.640    6.184   118.1     8.3  18.6
2024 08 08    17 36.19   -77 28.6    5.699    6.169   113.2     8.7  18.6
2024 08 18    17 05.31   -75 57.4    5.779    6.155   107.2     9.0  18.6
2024 08 28    16 45.22   -74 14.8    5.875    6.142   100.6     9.3  18.7
2024 09 07    16 33.17   -72 30.8    5.983    6.129    93.6     9.4  18.7
2024 09 17    16 26.84   -70 51.6    6.098    6.117    86.3     9.4  18.7
2024 09 27    16 24.53   -69 20.7    6.216    6.106    79.1     9.3  18.8
2024 10 07    16 25.09   -67 59.7    6.331    6.095    71.9     9.0  18.8
2024 10 17    16 27.71   -66 49.5    6.439    6.086    65.0     8.5  18.8
2024 10 27    16 31.79   -65 50.3    6.537    6.077    58.5     8.0  18.8
2024 11 06    16 36.91   -65 01.8    6.620    6.069    52.6     7.5  18.9
2024 11 16    16 42.72   -64 23.8    6.686    6.062    47.5     6.9  18.9
2024 11 26    16 48.93   -63 55.6    6.732    6.055    43.6     6.4  18.9
2024 12 06    16 55.30   -63 37.1    6.757    6.049    41.1     6.2  18.9
2024 12 16    17 01.58   -63 27.7    6.759    6.045    40.5     6.1  18.9
2024 12 26    17 07.53   -63 27.1    6.738    6.041    41.8     6.2  18.9
2025 01 05    17 12.92   -63 35.1    6.694    6.037    44.9     6.6  18.9


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

                         (C) Copyright 2024 CBAT
2024 May 21                      (CBET 5397)              Daniel W. E. Green