Electronic Telegram No. 5139 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 P/2022 L3 (ATLAS) Peter Veres, Minor Planet Center, reports that he noticed cometary appearance of an object discovered on CCD images taken on June 12.6 UT with a 0.5-m f/2 Schmidt reflector at Mauna Loa, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program, adding that he was surprised that the ATLAS team had missed the cometary nature of the object. The discovery observations are tabulated below. 2022 UT R.A. (2000) Decl. Mag. June 12.57339 1 24 38.96 - 2 13 21.8 17.6 12.57708 1 24 39.34 - 2 13 18.9 17.2 12.58861 1 24 40.12 - 2 13 12.2 16.7 12.59419 1 24 40.63 - 2 13 08.0 17.4 12.59557 1 24 40.77 - 2 13 07.6 16.6 12.60661 1 24 41.60 - 2 13 00.7 16.7 12.60891 1 24 41.83 - 2 12 58.3 17.6 After the comet was posted on the MPC's PCCP webpage, other CCD astrometrists also reported to the Central Bureau on the cometary appearance. E. Guido, Castellammare di Stabia, Italy, writes that twenty stacked 60-s unfiltered exposures obtained remotely by a large group of observers on June 17.4 UT with a "Telescope Live" 0.61-m f/6.5 astrograph located at El Sauce, Chile, show a diffuse irregular coma about 10" in diameter with magnitude 17.1-17.4. Twelve stacked 60-s exposures taken remotely by H. Sato, Tokyo, Japan, with a 0.51-m f/6.8 astrograph located at Mayhill, NM, USA, on June 17.4 show a strongly condensed coma 12" in diameter with a 20" tail toward p.a. 230 degrees; the magnitude was 17.3 as measured within a circular aperture of radius 6".5. Fifty stacked 30-s exposures taken remotely on June 19.14-19.16 by A. Aletti, F. Bellini, L. Buzzi, and G. Galli with a 0.36-m f/8.4 reflector at Hakos, Namibia, in a very clear sky and moonlight reveal a condensed 6" coma with a straight tail at least 30" long in p.a. 235 degrees. A. Hale, Cloudcroft, NM, USA, writes that 300-s images taken remotely on June 19.4 with a Las Cumbres 0.40-m f/10 Schmidt-Cassegrain reflector at Cerro Tololo Interamerican Observatory show a condensed 8" coma and a straight tail 60" long in p.a. approximately 235 deg. Additional observations by Hale on June 24.4 using a Las Cumbres 0.40-m f/10 Schmidt-Cassegrain reflector at McDonald Observatory show a similar appearance to his June 19 images. Hale adds that 300-s exposures taken on June 28.2 with a Las Cumbres 0.40-m f/10 Schmidt-Cassegrain telescope at Teide/Tenerife suggest that the comet was more obvious and brighter than on previous nights, with a 7" coma and a straight tail of length 130" in p.a. 230 degrees. Ten stacked 60-s exposures taken remotely with a 0.50-m f/6.8 astrograph located at Siding Spring, NSW, Australia, on June 24.8 by M. Mattiazzo (Swan Hill, Victoria, Australia) show a strongly condensed coma about 10" in diameter and of mag 17.3, with a clear tail 2' long in p.a. 233 degrees. The available astrometry appear on MPEC 2022-M96. The following preliminary, unperturbed elliptical orbital elements by S. Nakano (Central Bureau) are from 49 observations spanning June 12-28 (mean residual 0".6), with Nakano noting that, while the observations still fit a parabola, it is likely to be a short-period comet (with a suggested pass of 2.25 AU from Jupiter this past March). Nakano was unable to find astrometry at previous returns in archival data. T = 2022 Oct. 31.16877 TT Peri. = 10.77106 e = 0.6176979 Node = 29.71425 2000.0 q = 2.4125748 AU Incl. = 21.56655 a = 6.3106499 AU n = 0.06217173 P = 15.9 years The following ephemeris by the undersigned from the above orbital elements uses photometric power-law parameters H = 10.5 and 2.5n = 10 for the magnitudes. Date TT R. A. (2000) Decl. Delta r Elong. Phase Mag. 2022 05 21 00 53.06 -06 25.0 3.310 2.785 50.9 16.4 17.5 2022 05 31 01 07.24 -04 32.4 3.176 2.744 56.2 17.9 17.4 2022 06 10 01 21.13 -02 41.6 3.036 2.706 61.6 19.3 17.2 2022 06 20 01 34.65 -00 52.6 2.894 2.669 67.2 20.5 17.1 2022 06 30 01 47.71 +00 54.3 2.749 2.635 72.8 21.6 16.9 2022 07 10 02 00.17 +02 39.1 2.603 2.602 78.7 22.5 16.7 2022 07 20 02 11.87 +04 22.1 2.457 2.572 84.8 23.2 16.6 2022 07 30 02 22.60 +06 03.4 2.312 2.543 91.2 23.5 16.4 2022 08 09 02 32.12 +07 43.5 2.170 2.518 97.9 23.5 16.2 2022 08 19 02 40.14 +09 23.3 2.032 2.495 105.0 23.1 16.0 2022 08 29 02 46.31 +11 03.4 1.902 2.474 112.7 22.1 15.8 2022 09 08 02 50.27 +12 44.5 1.781 2.456 121.0 20.6 15.7 2022 09 18 02 51.67 +14 27.1 1.672 2.442 129.9 18.4 15.5 2022 09 28 02 50.22 +16 10.8 1.578 2.430 139.6 15.5 15.3 2022 10 08 02 45.87 +17 54.0 1.504 2.421 149.9 12.0 15.2 2022 10 18 02 38.90 +19 34.2 1.453 2.415 160.5 7.9 15.1 2022 10 28 02 30.01 +21 07.6 1.427 2.413 170.3 4.0 15.1 2022 11 07 02 20.34 +22 31.2 1.429 2.413 171.0 3.7 15.1 2022 11 17 02 11.24 +23 43.9 1.459 2.417 161.5 7.4 15.2 2022 11 27 02 03.94 +24 46.7 1.514 2.424 150.9 11.4 15.2 2022 12 07 01 59.35 +25 43.0 1.592 2.434 140.5 14.9 15.4 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2022 CBAT 2022 June 29 (CBET 5139) Daniel W. E. Green