Electronic Telegram No. 5119 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 X1 (MAURY-ATTARD) Alain Maury reports that Georges Attard (Mougins, France) and he have discovered another comet on images obtained on 2021 Dec. 2 (discovery astrometry tabulated below), with the object described as appearing "a bit fuzzy" on images obtained with a 0.28-m f/2.2 Schmidt reflector at San Pedro de Atacama, Chile, in the course of their "Maury, Attard, Parrott" (MAP) survey project. The comet showed a 4".5 coma in 2" seeing. The Minor Planet Center inadvertently issued the designation A/2021 X1 when announcing this object on MPEC 2021-X157 on 2021 Dec. 8. 2021 UT R.A. (2000) Decl. Mag. Observer Dec. 2.32400 8 25 15.77 -22 38 26.1 19.0 Maury 2.32983 8 25 15.49 -22 38 28.1 18.8 " 2.33560 8 25 15.23 -22 38 30.6 19.6 " After the object was posted on the MPC's PCCP website, and for the past half year, numerous CCD astrometrists have continually noted the cometary appearance. Twelve stacked 60-s exposures taken remotely by Hidetaka Sato (Tokyo, Japan) with a 0.51-m astrograph located at Siding Spring, NSW, on 2021 Dec. 3.7 UT showed a stellar appearance; the magnitude was 19.2 as measured within a circular aperture of radius 4".9. Six stacked subsequent 60-s exposures taken by Sato with the same telescope on 2022 Mar. 22.4 show a strongly condensed coma 10" in diameter with no tail; the magnitude was then 17.3 as measured within a circular aperture of radius 6".5. C. Jacques, Belo Horizonte, MG, Brazil, writes that a stacked image composed of one- hundred-twenty 30-s exposures obtained on 2021 Dec. 10.15 with a 0.45-m reflector at the SONEAR Observatory, Oliveira, show a condensed-but-elongated coma of size 8".6 x 5".7 (elongated toward p.a. 317 degrees) in 4".4 seeing with no tail. Forty stacked 60-s exposures taken remotely by Jacques with a 0.5-m reflector at Siding Spring on 2021 Dec. 30.6 show a condensed coma of size 6".5 in 2".6 seeing, again with no tail. M. Micheli writes that images obtained on Dec. 29.5 with the 3.6-m Canada-France-Hawaii Telescope at Mauna Kea show a coma of size about 6" that was slightly elongated toward p.a. about 45 degrees. L. Buzzi, Varese, Italy, notes that seventy-five stacked 30-s exposures taken by A. Aletti and himself with a 0.84-m f/3.5 reflector on 2022 Feb. 23.8 in good conditions show a condensed coma 7" wide with a faint tail about 7" long in p.a. 90 degrees; the magnitude was given as 18.0. Buzzi adds that fifteen stacked 60-s exposures taken remotely by L. Demetz and himself with a 0.51-m f/6.7 astrograph of the Skygems Telescope Network in Namibia in 2".5 seeing on Feb. 23.85-23.87 (measured by Aletti, Buzzi, and G. Galli) show a condensed coma 5" wide with a faint, broad tail about 5" long in p.a. about 90 degrees. Forty stacked 60-s exposures taken by Buzzi's group remotely using a 0.36-m reflector at the Hakus Guest Farm in central Namibia in fair seeing on May 2.74-2.76 show a condensed coma 6" wide (mag 18.1) with a faint, straight tail at least 10" long in p.a. 100 degrees; the astrometry by Aletti and Buzzi on May 2 are tabulated below. Eight stacked 60-s exposures taken on Mar. 8.5 with a 0.38-m reflector at Shinshiro, Japan, by T. Ikemura and Hirohisa Sato show a moderately condensed coma about 9" in diameter with no tail; the total magnitude was given as 17.2. 2022 UT R.A. (2000) Decl. Mag. Observer May 2.74483 6 16 49.94 -12 40 56.9 Aletti 2.76094 6 16 49.97 -12 40 51.4 18.1 " K. Ly (El Monte, CA, USA) identified pre-discovery observations of this comet in archival CCD images taken by the "Zwicky Transient Facility" (ZTF) with the Palomar 1.2-m f/2.4 Schmidt reflector on 2021 Oct. 22 (r-band and g-band), Oct. 31 (g-band), and Nov. 4 (r-band), with his astrometry tabulated below; he notes that the comet is substantially fainter than predicted and exhibits a sharp increase in brightness between October and November, adding that the comet appears asteroidal in all four ZTF images, with no obvious extensions or cometary features. Ly adds that the comet is not visible at the predicted position in archival DECam i-band 90-s images taken with the Cerro Tololo 4-m reflector on 2021 Jan. 22.17 and 23.10 UT (limiting mag 23). 2021 UT R.A. (2000) Decl. Mag. Oct. 22.48151 8 42 47.83 -18 23 28.4 20.6 22.51816 8 42 47.51 -18 23 42.3 20.9 31.44827 8 41 03.82 -19 20 32.8 20.4 Nov. 4.46202 8 39 56.46 -19 46 26.8 19.8 Additional astrometry appears on MPEC 2021-J33. The following orbital elements by S. Nakano (Central Bureau) are from 279 observations spanning 2021 Oct. 22-2022 May 2 (mean residual 0".3), with corresponding original and future values of 1/a being +0.000279 and +0.000096 AU**-1, respectively (formal error +/- 0.000009 AU**-1), indicating that the comet will pass 1.87 AU from Jupiter on 2023 July 5 UT. Epoch = 2023 May 16.0 TT T = 2023 May 27.42273 TT Peri. = 334.61777 e = 1.0009101 Node = 10.58658 2000.0 q = 3.2336825 AU Incl. = 140.11931 The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 8.0, 2.5n = 8 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 04 11 06 19.18 -15 09.3 5.063 4.960 78.4 11.4 17.1 2022 04 21 06 17.38 -13 56.5 5.145 4.896 70.1 11.1 17.1 2022 05 01 06 16.82 -12 51.5 5.218 4.832 62.3 10.6 17.1 2022 05 11 06 17.31 -11 55.0 5.278 4.769 54.9 10.0 17.0 2022 05 21 06 18.65 -11 07.6 5.321 4.706 48.1 9.2 17.0 2022 05 31 06 20.68 -10 29.6 5.344 4.643 42.2 8.4 17.0 2022 06 10 06 23.23 -10 01.2 5.346 4.581 37.4 7.7 16.9 2022 06 20 06 26.13 -09 42.4 5.325 4.520 34.1 7.2 16.9 2022 06 30 06 29.23 -09 33.2 5.280 4.459 32.8 7.1 16.8 2022 07 10 06 32.37 -09 33.9 5.210 4.399 33.6 7.3 16.7 2022 07 20 06 35.38 -09 44.4 5.116 4.340 36.4 8.0 16.6 2022 07 30 06 38.11 -10 05.0 4.998 4.281 40.8 8.9 16.5 2022 08 09 06 40.36 -10 35.7 4.858 4.224 46.5 10.0 16.4 2022 08 19 06 41.92 -11 16.9 4.697 4.167 53.0 11.2 16.3 2022 08 29 06 42.55 -12 08.6 4.518 4.111 60.2 12.3 16.2 2022 09 08 06 41.96 -13 11.1 4.324 4.056 68.0 13.3 16.0 2022 09 18 06 39.81 -14 24.2 4.120 4.002 76.3 14.1 15.9 2022 09 28 06 35.72 -15 47.4 3.910 3.949 84.9 14.6 15.7 2022 10 08 06 29.22 -17 19.3 3.699 3.898 93.9 14.8 15.6 2022 10 18 06 19.84 -18 57.2 3.496 3.848 103.2 14.6 15.4 2022 10 28 06 07.10 -20 36.5 3.308 3.799 112.3 14.0 15.2 2022 11 07 05 50.68 -22 09.8 3.144 3.751 121.0 13.1 15.1 2022 11 17 05 30.59 -23 27.1 3.012 3.706 128.2 12.1 14.9 2022 11 27 05 07.36 -24 17.2 2.921 3.661 132.6 11.4 14.8 2022 12 07 04 42.22 -24 29.9 2.875 3.619 132.9 11.5 14.8 2022 12 17 04 16.88 -24 01.1 2.878 3.578 128.8 12.4 14.7 2022 12 27 03 53.07 -22 53.1 2.925 3.539 121.4 13.7 14.7 2023 01 06 03 32.15 -21 14.5 3.012 3.502 112.0 15.1 14.7 2023 01 16 03 14.78 -19 16.3 3.130 3.467 101.8 16.1 14.8 2023 01 26 03 01.07 -17 08.4 3.268 3.434 91.3 16.7 14.9 2023 02 05 02 50.75 -14 58.3 3.418 3.404 80.9 16.6 14.9 2023 02 15 02 43.35 -12 51.0 3.569 3.375 70.8 16.0 15.0 2023 02 25 02 38.38 -10 49.1 3.716 3.349 61.0 15.0 15.1 2023 03 07 02 35.38 -08 54.0 3.851 3.326 51.5 13.5 15.1 2023 03 17 02 33.93 -07 06.2 3.969 3.305 42.5 11.7 15.1 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 May 5 (CBET 5119) Daniel W. E. Green