Seiichi Yoshida's Diary of Comet Observations (2023)

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Updated on October 23, 2023

Detailed observation data in ICQ format.

2023 Oct. 20 (2 comets) I observed 2 comets visually on Oct. 20 in Kita-karuizawa, Gunma, Japan. C/2023 H2 ( Lemmon ) 9.4 mag   Dia. 6'   DC 4-5   (40.0-cm reflector 36x) I was surprised that it was much brighter than expected! I felt it was much brighter and easier to see than 103P. 103P/Hartley 2 8.9 mag   Dia. 5'   DC 3   (40.0-cm reflector 36x) More diffuse than expected.

2023 Aug. 29 (3 comets) I observed 3 comets visually on Aug. 29 in Mt. Tsukuba, Ibaraki, Japan. I went to observe the bright new comet C/2023 P1 ( Nishimura ). The weather was very humid, and the summit of Mt. Tsukuba was often covered with clouds. But fortunately, the eastern sky was clear down to the horizon, and I could see Comet Nishimura. C/2020 V2 ( ZTF ) 11.1 mag   Dia. 2.5'   DC 6   (40.0-cm reflector 75x) Strongly condensed and easy to see. C/2023 P1 ( Nishimura ) 7.2 mag   Dia. 5.0'   DC 7   (40.0-cm reflector 36x) Very strongly condensed, bright, and easy to see. 2P/Encke 12.7 mag   Dia. 0.7'   DC 2   (40.0-cm reflector 257x) Probably I could see its central part only.

2023 July 22 (5 comets) I observed 5 comets visually on July 22 in Mt. Tsukuba, Ibaraki, Japan, and in Toride City, Ibaraki, Japan. I went to observe 12P/Pons-Brooks just in outburst. It is really amazing to observe this comet for the first time in such an unexpected event. C/2020 V2 ( ZTF ) 10.3 mag   Dia. 1.6'   DC 4   (40.0-cm reflector 144x) Looks diffuse due to the light pollution. C/2022 A2 ( PanSTARRS ) 12.6 mag   Dia. 0.7'   DC 1   (40.0-cm reflector 257x) Hard to see due to the light pollution. C/2023 E1 ( ATLAS ) 9.0 mag   Dia. 5'   DC 2   (40.0-cm reflector 36x) Diffuse and large. 12P/Pons-Brooks 12.1 mag   Dia. smaller than 0.5'   DC 8-9   (40.0-cm reflector 75x) 11.9 mag   Dia. 0.6'   DC 8   (40.0-cm reflector 144x) Very strongly condensend and looks sharp. Almost stellar with a low magnification. Looks like a planetary nebula with a high magnification. 237P/LINEAR 12.9 mag   Dia. 0.4'   DC 4   (40.0-cm reflector 144x) Small.

2023 July 16-17 (6 comets) I observed 6 comets visually on July 16 and 17 in Kita-karuizawa, Gunma, Japan. The weather was fine, but very hot and somewhat humid. C/2020 V2 ( ZTF ) July 16   10.2 mag   Dia. 3.2'   DC 7   (40.0-cm reflector 75x) Strongly condensed, bright and large, and easy to see. C/2022 A2 ( PanSTARRS ) July 16   12.8 mag   Dia. 1.3'   DC 3   (40.0-cm reflector 144x) July 17   12.0 mag   Dia. 1.0'   DC 2   (40.0-cm reflector 144x) Somewhat diffuse, but well visible. C/2023 E1 ( ATLAS ) July 16   9.3 mag   Dia. 5'   DC 4   (40.0-cm reflector 36x) July 17   8.9 mag   Dia. 4.4'   DC 3   (40.0-cm reflector 36x) Bright and easy to see. Near by Polaris and observable all night. 126P/IRAS July 16   14.0 mag   Dia. 0.2'   DC 3   (40.0-cm reflector 257x) Near limit. 185P/Petriew July 16   fainter than 11.9 mag   Dia. 0.8'   (40.0-cm reflector 257x) In the morning glow, the comet was not visible. 237P/LINEAR July 16   13.0 mag   Dia. 0.7'   DC 5   (40.0-cm reflector 144x) July 17   12.4 mag   Dia. 0.7'   DC 4   (40.0-cm reflector 144x) Small but well visible.

Go to Seiichi Yoshida's Diary of Comet Observations in 2022.