Electronic Telegram No. 5095 Central Bureau for Astronomical Telegrams Mailing address: Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network 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 19.39745 13 56 15.19 +12 37 21.5 " 19.40271 13 56 14.94 +12 37 25.1 20.9 " 19.40795 13 56 14.71 +12 37 29.7 21.3 " 19.40991 13 56 14.73 +12 37 30.8 21.8 Pan-STARRS1 19.42197 13 56 14.22 +12 37 39.3 21.8 " 19.43402 13 56 13.72 +12 37 47.5 21.9 " 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. Ten 60-s CCD exposures taken remotely by M. Mattiazzo (Swan Hill, Victoria, Australia) with a 0.32-m f/8 astrograph located at Nerpio, Spain, on 2022 Jan. 1.2 show a diffuse object of size 5" (full-width-at-half-maximum) with V magnitude 17.2. L. Buzzi, Varese, Italy, writes that fifty stacked 30-s CCD exposures taken with a 0.84-m f/3.5 reflector on Jan. 7.2 (and measured by A. Aletti) show clear cometary activity, with a condensed 15" coma surrounded by a faint, round outer coma at least 60" wide; this outer coma was not centered on the pseudo-nucleus but extended toward the north, and the magnitude was 17.4 as measured within an aperture radius of 9". Buzzi adds that seventy-five stacked 30-s exposures taken by Aletti with a 0.20-m f/4 reflector at Varese on Jan. 7.2 show a moderately condensed coma with an outer part that can be followed for at least 40", noting that the coma's edge is softer toward the north, with a possible very broad, fan-shaped tail spanning p.a. approximately 300-350 degrees; the magnitude was 16.4 as s measured within an aperture radius of 10". 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. CCD exposures taken remotely on Jan. 21.5 by K. Yoshimoto, Yamaguchi, Japan, using a 0.43-m f/6.8 reflector near Mayhill show a faint coma 1'.6 in diameter (total mag 13.8) with a concentrated center. Ten stacked 60-s CCD exposures taken on Jan. 24.7 by Hirohisa Sato at Sukagawa, Japan, with a 0.25-m f/4 reflector show a strongly condensed faint coma about 1'.4 in diameter with no tail; the total magnitude was measured to be 14.3. A. Hale, Cloudcroft, NM, USA, writes that two 5-min exposures taken remotely on Jan. 28.66 using a 0.4-m telescope at the Las Cumbres Observatory atop Haleakala, HI, USA, show a condensed coma 1'.0 in diameter with a distinct condensation within a moderately bright inner coma, along with what appears to be a fainter, diffuse outer coma. A CCD image taken on Jan. 30.55 by C. S. Morris at Fillmore, CA, USA, with a 0.41-m Schmidt-Cassegrain reflector shows a coma of diameter 4'.4 with total mag 12.8. The available astrometry appears on MPEC 2022-C15. 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 by the undersigned 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 01 21 17 31.44 +42 24.8 1.580 1.590 72.5 36.2 14.1 2022 01 26 18 03.45 +44 44.3 1.516 1.532 72.1 37.7 13.9 2022 01 31 18 39.95 +46 44.9 1.466 1.475 70.9 39.2 13.7 2022 02 05 19 20.51 +48 13.0 1.432 1.418 69.0 40.5 13.5 2022 02 10 20 03.82 +48 55.8 1.414 1.363 66.5 41.6 13.3 2022 02 15 20 47.77 +48 46.4 1.413 1.310 63.3 42.3 13.2 2022 02 20 21 30.01 +47 45.6 1.427 1.260 59.6 42.6 13.1 2022 02 25 22 08.74 +46 01.5 1.455 1.212 55.5 42.3 13.0 2022 03 02 22 43.05 +43 46.1 1.495 1.167 51.2 41.5 12.9 2022 03 07 23 12.83 +41 11.1 1.544 1.126 46.7 39.9 12.9 2022 03 12 23 38.47 +38 26.1 1.600 1.089 42.0 37.7 12.8 2022 03 17 00 00.56 +35 37.5 1.659 1.058 37.4 34.8 12.8 2022 03 22 00 19.72 +32 49.6 1.720 1.032 32.6 31.4 12.8 2022 06 10 03 05.64 -06 52.9 2.025 1.454 42.8 28.3 14.3 2022 06 20 03 22.04 -12 31.1 1.986 1.570 51.5 30.4 14.6 2022 06 30 03 38.45 -18 38.9 1.949 1.688 60.0 31.4 14.8 2022 07 10 03 54.85 -25 16.8 1.923 1.809 68.1 31.4 15.0 2022 07 20 04 11.23 -32 20.6 1.914 1.930 75.5 30.7 15.2 2022 07 30 04 27.50 -39 40.9 1.928 2.051 82.1 29.4 15.4 2022 08 09 04 43.49 -47 03.9 1.969 2.173 87.3 27.8 15.7 2022 08 19 04 58.99 -54 14.3 2.040 2.293 91.0 26.2 15.9 2022 08 29 05 13.60 -60 58.8 2.140 2.413 93.0 24.7 16.2 2022 09 08 05 26.60 -67 07.9 2.266 2.533 93.3 23.4 16.5 2022 09 18 05 36.76 -72 36.9 2.413 2.651 92.3 22.3 16.8 2022 09 28 05 41.43 -77 24.6 2.577 2.768 90.2 21.2 17.1 2022 10 08 05 34.07 -81 30.7 2.754 2.884 87.2 20.3 17.4 2022 10 18 04 55.33 -84 50.3 2.937 2.999 83.8 19.3 17.7 2022 10 28 02 47.50 -86 51.8 3.124 3.112 80.2 18.3 17.9 2022 11 07 23 48.16 -86 26.8 3.310 3.225 76.4 17.4 18.2 2022 11 17 22 35.77 -84 39.9 3.493 3.337 72.8 16.4 18.4 2022 11 27 22 17.41 -82 44.1 3.668 3.447 69.4 15.5 18.6 2022 12 07 22 18.04 -80 55.6 3.835 3.556 66.4 14.7 18.8 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 February 2 (CBET 5095) Daniel W. E. Green