Recent Comet Brightness Estimates

21P/Giacobini-Zinner
Total-magnitude and coma-diameter estimates:
2018 May. 23.33, 15.1, 0.4' (M. Masek, 0.3-m Schmidt-Cassegrain)
2018 May. 18.02, 15.0, -- (C. Harder, Klipfontain nahe Vryburg/SA, 0.4-m Newtonian reflector)
2018 May. 17.35, 14.8, 0.6' (R. Ramlow, 0.25-m Newtonian reflector; 0.7' tail in p.a. 250)
2018 May. 10.38, 15.4, 0.6' (R. Ramlow, 0.25-m Newtonian reflector; 0.6' tail in p.a. 255)
2018 May. 09.35, 14.9, 1.5' (T. Lehmann, 0.51-m Newtonian reflector)
2018 Apr. 27.78, 16.4, 0.9' (T. Lehmann, 0.4-m Newtonian reflector)

29P/Schwassmann-Wachmann
Total-magnitude and coma-diameter estimates:
2018 May. 25.75, [14.5, -- (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 21.75, [15.0, -- (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 20.41, 16.7, 0.3' (M. Masek, 0.3-m Schmidt-Cassegrain)
2018 May. 19.76, [14.7, -- (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 18.76, [14.6, -- (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 15.10, 15.5, -- (C. Harder, Klipfontain nahe Vryburg/SA, 0.4-m Newtonian reflector)

30P/Reinmuth
Total-magnitude and coma-diameter estimates:
2018 May. 21.25, 19.1, 0.2' (M. Masek, 0.3-m Schmidt-Cassegrain)

37P/Forbes
Total-magnitude and coma-diameter estimates:
2018 May. 25.73, 12.7, 1.7' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 22.73, 12.6, 1.5' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 21.73, 12.5, 1.7' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 21.34, 13.0, 1.4' (M. Masek, 0.3-m Schmidt-Cassegrain; 3.4' tail in p.a. 242)
2018 May. 21.14, 10.7, 4' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 20.07, 12.0, 2' (C. Harder, Klipfontain nahe Vryburg/SA, 0.4-m Newtonian reflector)
2018 May. 19.74, 12.5, 1.6' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 19.02, 12.0, 1.2' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 18.74, 12.4, 1.5' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 18.01, 11.5, 2' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 16.12, 11.5, 1.5' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 16.07, 12.5, 1.2' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 15.07, 11.5, 2.8' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 10.64, 12.5, 1.4' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 09.64, 12.6, 1.3' (C. Wyatt, 0.25-m Newtonian reflector)
2018 Apr. 26.74, 13.0, 1.4' (C. Wyatt, 0.25-m Newtonian reflector)

48P/Johnson
Total-magnitude and coma-diameter estimates:
2018 May. 23.29, 15.5, 0.4' (M. Masek, 0.3-m Schmidt-Cassegrain; 0.2' tail in p.a. 271)
2018 May. 14.78, 15.5, 0.4' (R. Ramlow, 0.7-m Newtonian reflector)

62P/Tsuchinshan
Total-magnitude and coma-diameter estimates:
2018 May. 21.21, 20.4, 0.1' (M. Masek, 0.3-m Schmidt-Cassegrain)
2018 May. 02.91, 17.1, 0.2' (K. Hills, 0.5-m Newtonian reflector)

65P/Gunn
Total-magnitude and coma-diameter estimates:
2018 May. 21.42, 17.2, 0.2' (M. Masek, 0.3-m Schmidt-Cassegrain)

66P/du Toit
Total-magnitude and coma-diameter estimates:
2018 May. 25.74, 10.7, 6.5' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 24.78, 10.2, 7.1' (R. Ramlow, 0.09-m refractor)
2018 May. 22.74, 10.2, 5.8' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 21.73, 10.6, 4.4' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 20.37, 11.9, 3' (M. Masek, 0.3-m Schmidt-Cassegrain)
2018 May. 20.33, 11.2, 3' (M. Goiato, 0.22-m Newtonian reflector)
2018 May. 20.07, 10.4, 5' (C. Harder, Klipfontain nahe Vryburg/SA, 0.4-m Newtonian reflector)
2018 May. 19.75, 10.5, 6.6' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 19.01, 10.7, 4.5' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 18.75, 10.4, 5.8' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 18.01, 10.6, 4' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 17.04, 10.2, 4.8' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 16.09, 10.4, 4.5' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 15.05, 10.5, 3.7' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 13.78, 10.3, 15' (T. Lehmann, 0.106-m refractor)
2018 May. 13.01, 11.4, 1.7' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 11.03, 11.0, 3' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 10.63, 10.6, 3.8' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 09.65, 10.5, 4.1' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 05.80, 10.5, 12' (T. Lehmann, 0.106-m refractor)
2018 May. 04.77, 10.6, 7' (R. Ramlow, 0.106-m refractor)
2018 Apr. 27.78, 10.5, 13' (T. Lehmann, 0.106-m refractor)
2018 Apr. 26.73, 11.3, 4.5' (C. Wyatt, 0.25-m Newtonian reflector)

74P/Smirnova-Chernykh
Total-magnitude and coma-diameter estimates:
2018 May. 05.88, 16.3, 0.9' (T. Lehmann, 0.2-m Newtonian reflector; 0.02-deg tail in p.a. 296)
2018 May. 04.90, 16.2, 1.9' (S. Fritsche, 0.065-m refractor)

78P/Gehrels
Total-magnitude and coma-diameter estimates:
2018 May. 24.31, 18.4, 0.2' (M. Masek, 0.3-m Schmidt-Cassegrain)

143P/Kowal-Mrkos
Total-magnitude and coma-diameter estimates:
2018 May. 21.16, 17.9, 0.2' (M. Masek, 0.3-m Schmidt-Cassegrain)

186P/Garradd
Total-magnitude and coma-diameter estimates:
2018 May. 23.25, 17.7, 0.2' (M. Masek, 0.3-m Schmidt-Cassegrain)

235P/LINEAR
Total-magnitude and coma-diameter estimates:
2018 May. 02.92, 18.5, 0.2' (K. Hills, 0.5-m Newtonian reflector)

364P/PANSTARRS
Total-magnitude and coma-diameter estimates:
2018 May. 19.16, 14.7, 0.3' (R. Ramlow, 0.25-m Newtonian reflector; 3.1' tail in p.a. 96)
2018 May. 09.23, 15.7, 0.3' (R. Ramlow, 0.25-m Newtonian reflector; 0.8' tail in p.a. 91)
2018 May. 02.95, 17.0, 0.3' (K. Hills, 0.5-m Newtonian reflector)

365P/PANSTARRS
Total-magnitude and coma-diameter estimates:
2018 May. 03.90, 18.2, 0.2' (K. Hills, 0.5-m Newtonian reflector)

C/2010 U3 (Boattini)
Total-magnitude and coma-diameter estimates:
2018 May. 02.93, 15.6, 0.4' (K. Hills, 0.5-m Newtonian reflector)

C/2015 O1 (PANSTARRS)
Total-magnitude and coma-diameter estimates:
2018 May. 15.99, 12.0, 1.2' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 08.96, 12.2, 1.2' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 07.98, 13.6, 0.8' (J. Bohusz, Myślin Poland, 0.25-m Newtonian reflector)
2018 May. 07.98, 12.6, 1.1' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 07.87, 13.5, 2.7' (T. Lehmann, 0.075-m reflector; 0.08-deg tail in p.a. 103)
2018 May. 07.83, 13.7, 0.46' (P. Michalik, Stredni Cechy, 0.8-m refractor)
2018 May. 06.98, 12.5, 1.2' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 06.94, 13.5, 2.7' (T. Lehmann, 0.075-m reflector; 0.08-deg tail in p.a. 105)
2018 May. 06.92, 13.5, 3.4' (S. Fritsche, 0.1-m refractor; 0.05-deg tail in p.a. 106)
2018 May. 05.96, 14.0, 0.5' (J. Warell, Lindby Observatory (K60), Skurup, Sweden , 0.22-m Newtonian reflector)
2018 May. 05.96, 13.7, 0.6' (M. Paradowski, Dąbrowa, Poland, 0.3-m Newtonian reflector)
2018 May. 05.96, 13.6, 1.6' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector)
2018 May. 05.96, 13.5, 1.6' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector)
2018 May. 05.96, 13.4, 1.6' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector)
2018 May. 05.96, 13.3, 1.6' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector)
2018 May. 05.96, 13.2, 1.6' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector)
2018 May. 05.93, 12.9, 0.8' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 04.97, 13.3, 4.3' (S. Fritsche, 0.065-m refractor; 0.03-deg tail in p.a. 116)
2018 May. 04.94, 12.2, 1' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 04.50, 13.1, 1.2' (S. Yoshida, 0.4-m Newtonian reflector)
2018 May. 04.16, 13.5, 3' (T. Lehmann, 0.106-m refractor; 0.1-deg tail in p.a. 108)
2018 May. 03.91, 12.8, 0.8' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 03.53, 13.5, 0.8' (S. Yoshida, 0.4-m Newtonian reflector)
2018 Apr. 26.28, 13.8, 2' (T. Lehmann, 0.106-m refractor; 0.04-deg tail in p.a. 121)

C/2015 V2 (Johnson)
Total-magnitude and coma-diameter estimates:
2018 May. 23.42, 14.8, 0.6' (M. Masek, 0.3-m Schmidt-Cassegrain; 0.5' tail in p.a. 216)
2018 May. 14.80, 14.6, 2.7' (T. Lehmann, 0.4-m Newtonian reflector; 0.24-deg tail in p.a. 224)

C/2016 M1 (PANSTARRS)
Total-magnitude and coma-diameter estimates:
2018 May. 25.72, 9.6, 2.9' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 24.46, 9.1, 4' (C. Hergenrother, 30x125 binoculars)
2018 May. 23.01, 10.3, 2' (A. Novichonok, 0.15-m Newtonian reflector)
2018 May. 22.72, 9.6, 4.2' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 22.46, 9.1, 3' (C. Hergenrother, 30x125 binoculars)
2018 May. 22.00, 10.5, 2' (A. Novichonok, 0.15-m Newtonian reflector)
2018 May. 21.72, 10.0, 5' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 21.29, 9.7, 5.1' (M. Masek, 0.3-m Schmidt-Cassegrain)
2018 May. 21.07, 8.9, 5' (J. Gonzalez Suarez, 25x100 binoculars)
2018 May. 21.06, 9.1, 5' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 21.03, 10.3, 4.1' (J. Bohusz, Myślin Poland, 0.25-m Newtonian reflector)
2018 May. 21.00, 10.4, 2.2' (A. Novichonok, 0.15-m Newtonian reflector)
2018 May. 20.31, 9.7, 4' (M. Goiato, 0.22-m Newtonian reflector)
2018 May. 20.09, 9.6, 4' (C. Labordena, La Serra, 0.2-m Schmidt-Cassegrain)
2018 May. 20.00, 9.6, 6' (C. Harder, Klipfontain nahe Vryburg/SA, 0.4-m Newtonian reflector)
2018 May. 19.72, 10.2, 4.7' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 19.00, 9.5, 5.5' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 18.99, 10.4, 2' (A. Novichonok, 0.15-m Newtonian reflector)
2018 May. 18.73, 10.2, 3.5' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 18.46, 9.6, 3' (C. Hergenrother, 30x125 binoculars)
2018 May. 17.95, 9.5, 6' (C. Harder, Klipfontain/Vryburg SA, 0.198-m Newtonian reflector)
2018 May. 17.01, 10.2, 2.1' (A. Novichonok, 0.15-m Newtonian reflector)
2018 May. 16.95, 9.4, 7.5' (C. Harder, Klipfontain/Vryburg SA, 0.198-m Newtonian reflector)
2018 May. 16.02, 9.0, 4' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 15.94, 9.8, 4.8' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 15.46, 9.6, 4' (C. Hergenrother, 30x125 binoculars)
2018 May. 14.95, 9.0, 4.5' (C. Harder, Klipfontain/Vryburg SA, 0.198-m Newtonian reflector)
2018 May. 13.14, 9.6, 4' (C. Labordena, La Serra, 0.2-m Schmidt-Cassegrain)
2018 May. 12.95, 9.2, 4' (C. Harder, Klipfontain/Vryburg SA, 0.198-m Newtonian reflector)
2018 May. 12.77, 9.4, 9.3' (R. Ramlow, 0.09-m refractor)
2018 May. 12.46, 9.9, 4' (C. Hergenrother, 30x125 binoculars)
2018 May. 12.03, 9.4, 12' (T. Lehmann, 0.3-m Newtonian reflector)
2018 May. 11.98, 9.4, 5' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 10.97, 9.8, 3.3' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 10.62, 10.0, 3.2' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 10.36, 9.2, 19' (T. Lehmann, 0.106-m refractor)
2018 May. 09.89, 10.3, 2.9' (C. Harder, Klipfontain/Vryburg SA, 0.4-m Newtonian reflector)
2018 May. 09.59, 10.1, 4.7' (C. Wyatt, 0.25-m Newtonian reflector)
2018 May. 09.17, 10.6, 2.5' (M. Goiato, 0.22-m Newtonian reflector)
2018 May. 09.09, 9.3, 5' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 08.04, 10.2, 3' (U. Pilz, 0.32-m Newtonian reflector)
2018 May. 03.76, 10.5, 1.7' (S. Yoshida, 0.4-m Newtonian reflector)
2018 Apr. 26.72, 10.8, 3.2' (C. Wyatt, 0.25-m Newtonian reflector)

C/2016 N4 (MASTER)
Total-magnitude and coma-diameter estimates:
2018 May. 02.96, 16.0, 0.5' (K. Hills, 0.5-m Newtonian reflector)

C/2016 N6 (PANSTARRS)
Total-magnitude and coma-diameter estimates:
2018 May. 15.97, 11.6, 2' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 13.88, 12.6, 4.5' (T. Lehmann, 0.075-m reflector; 0.06-deg tail in p.a. 34)
2018 May. 08.94, 12.3, 6' (T. Lehmann, 0.075-m reflector; 0.08-deg tail in p.a. 36)
2018 May. 08.92, 11.8, 1.7' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 07.90, 12.3, 0.9' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector; 1.5' tail in p.a. 40)
2018 May. 06.91, 12.3, 1' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 06.91, 12.5, 5' (T. Lehmann, 0.075-m reflector; 0.05-deg tail in p.a. 37)
2018 May. 06.88, 12.6, 4.8' (S. Fritsche, 0.1-m refractor; 0.06-deg tail in p.a. 37)
2018 May. 06.85, 12.7, 2' (J. Navarro Pina, Puerto de la Cadena ( Murcia , Spain ), 0.305-m Newtonian reflector)
2018 May. 06.25, 12.4, 2.2' (R. Ramlow, 0.106-m refractor; 3.0' tail in p.a. 39)
2018 May. 05.94, 12.5, 1' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector; 1.5' tail in p.a. 40)
2018 May. 05.94, 13.5, 0.5' (J. Warell, Lindby Observatory (K60), Skurup, Sweden , 0.22-m Newtonian reflector)
2018 May. 05.92, 13.0, 1.2' (M. Paradowski, Dąbrowa, Poland, 0.3-m Newtonian reflector)
2018 May. 05.92, 12.5, 1.8' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector; 0.05-deg tail in p.a. 35)
2018 May. 05.92, 12.4, 1.8' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector; 0.05-deg tail in p.a. 35)
2018 May. 05.92, 12.3, 1.8' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector; 0.05-deg tail in p.a. 35)
2018 May. 05.92, 12.2, 1.8' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector; 0.05-deg tail in p.a. 35)
2018 May. 05.90, 12.3, 2' (U. Pilz, 0.105-m refractor)
2018 May. 04.96, 13.3, 0.7' (T. Karhula, Virsbo, Sweden, 0.305-m Newtonian reflector)
2018 May. 04.94, 12.7, 3.7' (S. Fritsche, 0.065-m refractor; 0.05-deg tail in p.a. 38)
2018 May. 04.90, 11.9, 1.2' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 04.57, 12.7, 1.1' (S. Yoshida, 0.4-m Newtonian reflector)
2018 May. 04.15, 12.4, 6.5' (T. Lehmann, 0.106-m refractor; 0.07-deg tail in p.a. 35)
2018 May. 03.89, 12.3, 1' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 03.51, 12.3, 1.4' (S. Yoshida, 0.4-m Newtonian reflector)
2018 May. 02.98, 12.3, 1.2' (K. Hills, 0.5-m Newtonian reflector)
2018 Apr. 27.93, 12.5, 5.5' (T. Lehmann, 0.075-m reflector; 0.07-deg tail in p.a. 35)

C/2016 R2 (PANSTARRS)
Total-magnitude and coma-diameter estimates:
2018 May. 15.90, 11.3, 2' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 11.87, 11.8, 1.5' (C. Labordena, La Serra, 0.2-m Schmidt-Cassegrain)
2018 May. 08.90, 11.1, 2.5' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 08.90, 10.9, 11' (T. Lehmann, 0.075-m reflector; 0.9-deg tail in p.a. 65)
2018 May. 07.90, 11.8, 2' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 07.87, 12.8, 0.8' (G. Scheerle, 0.235-m Schmidt-Cassegrain)
2018 May. 06.90, 11.4, 2.2' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 06.88, 11.1, 10' (T. Lehmann, 0.075-m reflector; 0.6-deg tail in p.a. 67)
2018 May. 05.89, 12.0, 1.7' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 05.88, 12.5, 1.4' (M. Paradowski, Dąbrowa, Poland, 0.05-m reflector)
2018 May. 05.87, 12.4, 1.2' (M. Paradowski, Dąbrowa, Poland, 0.3-m Newtonian reflector)
2018 May. 05.86, 12.6, 1.4' (G. Scheerle, 0.235-m Schmidt-Cassegrain)
2018 May. 04.92, 11.2, 2.2' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 04.48, 13.2, 0.6' (S. Yoshida, 0.4-m Newtonian reflector)
2018 May. 04.14, 11.2, 9' (T. Lehmann, 0.106-m refractor; 0.24-deg tail in p.a. 75)
2018 May. 03.90, 11.5, 1.8' (C. Harder, Jeersdorf, 0.531-m Newtonian reflector)
2018 May. 03.50, 13.1, 0.9' (S. Yoshida, 0.4-m Newtonian reflector)
2018 Apr. 30.85, 11.2, 8' (T. Lehmann, 0.075-m reflector; 0.3-deg tail in p.a. 77)
2018 Apr. 27.86, 11.2, 9' (T. Lehmann, 0.075-m reflector; 0.35-deg tail in p.a. 68)

C/2017 B3 (LINEAR)
Total-magnitude and coma-diameter estimates:
2018 May. 21.37, 15.2, 0.3' (M. Masek, 0.3-m Schmidt-Cassegrain)

C/2017 K2 (PANSTARRS)
Total-magnitude and coma-diameter estimates:
2018 May. 05.91, 17.7, 1' (S. Fritsche, 0.065-m refractor)

C/2017 M4 (ATLAS)
Total-magnitude and coma-diameter estimates:
2018 May. 06.97, 14.6, 2.2' (S. Fritsche, 0.1-m refractor)
2018 May. 05.00, 15.0, 1.6' (S. Fritsche, 0.065-m refractor)

C/2017 S3 (PANSTARRS)
Total-magnitude and coma-diameter estimates:
2018 May. 15.47, 16.9, 0.7' (C. Hergenrother, 0.51-m Ritchey-Chretien)

C/2018 A3 (ATLAS)
Total-magnitude and coma-diameter estimates:
2018 May. 07.92, 17.4, 0.6' (S. Fritsche, 0.1-m refractor)
2018 May. 07.00, 17.0, 0.3' (K. Hills, 0.5-m Newtonian reflector)

C/2018 C2 (Lemmon)
Total-magnitude and coma-diameter estimates:
2018 May. 06.99, 16.0, 0.3' (K. Hills, 0.5-m Newtonian reflector)
2018 May. 06.01, 15.9, 1.9' (S. Fritsche, 0.065-m refractor)

C/2018 EF9 (Lemmon)
Total-magnitude and coma-diameter estimates:
2018 May. 21.12, 11.5, 3.5' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 16.01, 11.8, 3' (J. Gonzalez Suarez, 0.203-m Schmidt-Cassegrain)
2018 May. 14.18, 13.7, 4.4' (R. Ramlow, 0.106-m refractor)
2018 May. 13.92, 13.5, 6.5' (T. Lehmann, 0.075-m reflector)
2018 May. 11.95, 13.5, 6.5' (T. Lehmann, 0.3-m Newtonian reflector)
2018 May. 07.97, 14.3, 3' (S. Fritsche, 0.1-m refractor)

C/2018 F1 (Grauer)
Total-magnitude and coma-diameter estimates:
2018 May. 07.86, 19.0, 0.4' (S. Fritsche, 0.1-m refractor)
2018 May. 06.96, 18.6, 0.2' (K. Hills, 0.5-m Newtonian reflector)