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THE ASTRONOMER Electronic Circular No 3677      2022 Feb 02 13.57UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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COMET C/2021 F1 (LEMMON-PANSTARRS)

An apparently asteroidal object discovered independently in CCD images taken
on 2021 Mar. 19.4 UT with the Mt. Lemmon Survey's 1.5-m reflector in Arizona
and with the Pan-STARRS1 1.8-m Ritchey-Chretien reflector at Haleakala,
Hawaii, and announced with the designation A/2021 F1 on MPEC 2021-H142, has
been found to show cometary activity by observers elsewhere in the past two
months.  The discovery observations are tabulated below.

     2021 UT             R.A. (2000) Decl.       Mag.   Observer
     Mar. 19.38963   13 56 15.48   +12 37 17.2   20.9   Mt. Lemmon
          19.44612   13 56 13.21   +12 37 55.8   21.9     "

Ten stacked 60-s CCD exposures taken remotely by H. Sato (Tokyo, Japan) on
2021 Dec. 1.5 UT with a 0.51-m astrograph located near Mayhill, NM, USA,
show a strongly condensed coma 12" in diameter with no tail; the magnitude
was 18.0 as measured within a circular aperture of radius 8".2.

K. Kadota, Ageo, Japan, found a faint coma of diameter 1'.2 and total V mag
15.4 with a central condensation but no tail on CCD images obtained with a
0.25-m reflector on Jan. 8.8.  Additional exposures by Kadota on Jan. 15.85
show a faint coma of diameter 3'.7 (and total mag 14.0) surrounding a
central condensation, again with no tail, while further exposures taken on
Jan. 18.80 show a central condensation surrounded by a faint coma of
diameter 3'.6 and total mag 13.8, again with no tail.

The following orbital elements by S. Nakano (CBAT) are from 190 observations
spanning 2021 Mar. 19-2022 Feb. 1 (mean residual 0".4); the corresponding
original and future values of 1/a are +0.004991 and +0.004482 AU**-1,
respectively (mean error +/-
0.000003 AU**-1), and indicate that the comet will pass 3.89 AU from Jupiter
on 2022 June 12 UT.

                    Epoch = 2022 Apr. 11.0 TT
     T = 2022 Apr.  6.87345 TT        Peri. = 146.82294
     e = 0.9958059                    Node  = 203.45149 2000.0
     q = 0.9954804 AU                 Incl. = 107.32454

The following ephemeris from the above orbital elements uses photometric
power-law parameters H = 11.5 and 2.5n = 8 for the magnitudes.

Date    TT    R. A. (2000) Decl.     Delta      r     Elong.  Phase  Mag.
2022 02 05    19 20.51   +48 13.0    1.432    1.418    69.0    13.5
2022 02 10    20 03.82   +48 55.8    1.414    1.363    66.5    13.3
2022 02 15    20 47.77   +48 46.4    1.413    1.310    63.3    13.2
2022 02 20    21 30.01   +47 45.6    1.427    1.260    59.6    13.1
2022 02 25    22 08.74   +46 01.5    1.455    1.212    55.5    13.0
2022 03 02    22 43.05   +43 46.1    1.495    1.167    51.2    12.9
2022 03 07    23 12.83   +41 11.1    1.544    1.126    46.7    12.9
2022 03 12    23 38.47   +38 26.1    1.600    1.089    42.0    12.8
2022 03 17    00 00.56   +35 37.5    1.659    1.058    37.4    12.8
2022 03 22    00 19.72   +32 49.6    1.720    1.032    32.6    12.8

Guy M Hurst

