Seiichi Yoshida's Diary of Comet Observations (2020)

Japanese version
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Updated on December 16, 2020

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Detailed observation data in ICQ format.

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* 2020 Dec. 14 (8 comets)

I observed 8 comets visually on Dec. 14 in Mt. Hanadate, Ibaraki, Japan.

I observed Geminids meteor shower. Although it was cloudy until evening, it became fine with very clear sky at night.

I enjoyed Jupiter and Saturn in the same field!

C/2019 L3 ( ATLAS )

14.0 mag   Dia. 0.5'   DC 6   (40.0-cm reflector 257x)

Strongly condensed.

C/2020 M3 ( ATLAS )

10.3 mag   Dia. 2.9'   DC 5   (40.0-cm reflector 75x)

The central condensation became stronger.

11P/Tempel-Swift-LINEAR

13.3 mag   Dia. 1.4'   DC 2-3   (40.0-cm reflector 144x)

Unexpectedly well visible, maybe due to the clear sky condition.

29P/Schwassmann-Wachmann 1

13.6 mag   Dia. 1.0'   DC 4   (40.0-cm reflector 257x)

Faint.

88P/Howell

10.7 mag   Dia. 2.8'   DC 3   (40.0-cm reflector 75x)

Still bright.

141P/Machholz 2

13.6 mag   Dia. 0.8'   DC 3   (40.0-cm reflector 144x)

Unexpectedly well visible.

156P/Russell-LINEAR

10.5 mag   Dia. 4.2'   DC 5   (40.0-cm reflector 36x)

It became brighter furthermore.

398P/Boattini

12.4 mag   Dia. 1.4'   DC 4   (40.0-cm reflector 144x)

Well visible.

* 2020 Nov. 21 (7 comets)

I observed 7 comets visually on Nov. 21 in Toride City and Mt. Tsukuba and Mt. Hanadate, Ibaraki, Japan.

The weather was fine, although the sky was temporarily covered with thin clouds.

In the evening, I enjoyed Jupiter and Saturn locating very close.

In the morning, I enjoyed an extremely bright shooting star, about -6 or -7 mag, in the eastern sky at 4:49 (JST).

C/2020 M3 ( ATLAS )

8.6 mag   Dia. 4.5'   DC 2-3   (40.0-cm reflector 36x)

Very diffuse and hard to see.

C/2020 S3 ( Erasmus )

7.1 mag   Dia. 2.9'   DC 7-8   (40.0-cm reflector 36x)

6.9 mag   Dia. 3'   DC 6   (10x70 monocular)

Very strongly condensed, bright and easy to see.

11P/Tempel-Swift-LINEAR

fainter than 14.0 mag   Dia. 0.5'   (40.0-cm reflector 257x)

It had been a lost comet 11D/Tempel-Swift for a long time. So it is impressive that finally I can try to see it vsiaully. But unfortunately, the comet was not visible.

29P/Schwassmann-Wachmann 1

12.8 mag   Dia. 0.9'   DC 6-7   (40.0-cm reflector 257x)

Just after a new outburst on Nov. 19. So it is very strongly condensed, bright and easy to see.

88P/Howell

10.9 mag   Dia. 1.0'   DC 1-2   (40.0-cm reflector 257x)

Very near by Jupiter and Saturn. Hard to see due to the strong city light.

156P/Russell-LINEAR

11.1 mag   Dia. 2.1'   DC 7-8   (40.0-cm reflector 75x)

Brightened very much since last month. Very strongly condensed and easy to see.

398P/Boattini

13.5 mag   Dia. 0.5'   DC 4   (40.0-cm reflector 257x)

Well visible unexpectedly.

* 2020 Oct. 20 (5 comets)

I observed 5 comets visually on Oct. 20 in Mt. Tsukuba, Ibaraki, Japan.

The weather was fine with no clouds. But the sky was not very clear.

C/2020 M3 ( ATLAS )

10.1 mag   Dia. 3.2'   DC 2-3   (40.0-cm reflector 75x)

The condensation was weaker than expected. Diffuse and hard to see.

C/2020 S3 ( Erasmus )

12.5 mag   Dia. 1.7'   DC 0   (40.0-cm reflector 144x)

Diffuse.

88P/Howell

8.6 mag   Dia. 1.5'   DC 1-2   (40.0-cm reflector 144x)

Hard to see due to the low sky condition.

156P/Russell-LINEAR

12.3 mag   Dia. 0.7'   DC 6-7   (40.0-cm reflector 257x)

Bright! Very strongly condensed and easy to see.

398P/Boattini

fainter than 13.3 mag   Dia. 0.4'   (40.0-cm reflector 257x)

Not visible still now.

* 2020 Sept. 21 (2 comets)

I observed 2 comets visually on Sept. 21 in Mt. Hanadate, Ibaraki, Japan.

The weather was mainly cloudy, but I could have clear sky in a short time.

I enjoyed star watching, Moon, Jupiter, Saturn and Mars.

C/2019 U6 ( Lemmon )

13.0 mag   Dia. 1.2'   DC 2   (40.0-cm reflector 144x)

Finally I could see it. It has already became very faint.

88P/Howell

8.8 mag   Dia. 2.5'   DC 2   (40.0-cm reflector 75x)

Fifth apparition in my observer's life. Hard to see due to the thin clouds in the low sky.

* 2020 July 19 (1 comet)

I observed C/2020 F3 ( NEOWISE ) visually on July 19 beside Tsurumi River in Yokohama City, Kanagawa, Japan.

Finally I could see the great comet NEOWISE! It is already fading now, but I am glad I could observe it when it looks as a great comet.

C/2020 F3 ( NEOWISE )

about 3.3 mag   DC 8   (10x66 monocular)

Now we are in rainy season in Japan. Today we could have a somewhat fine weather. But there were many clouds and I observed it through thin clouds. I waited for 45 minutes until the comet came away from a thick cloud. Comet NEOWISE looks great with a tail, even in the bad sky condition.

It was lucky that there were proper comaprison stars very near by the comet.

* 2020 Mar. 21 (3 comets)

I observed 3 comets visually on Mar. 21 in Mt. Tsukuba, Ibaraki, Japan.

The weather was fine with no clouds. But the sky condition was not clear.

I also tried to observe C/2019 Y1, but it was hidden by Mt. Tsukuba and I could not observe it.

C/2017 T2 ( PanSTARRS )

8.8 mag   Dia. 4.0'   DC 4-5   (40.0-cm reflector 36x)

Well condensed.

C/2019 Y4 ( ATLAS )

8.9 mag   Dia. 6.5'   DC 2-3   (40.0-cm reflector 36x)

Diffuse with weak condensation. I also enjoyed M81 and M82, although they located somewhat far away.

C/2020 A2 ( Iwamoto )

fainter than 12.2 mag   Dia. 1.0'   (40.0-cm reflector 257x)

Already not visible.

* 2020 Jan. 31 (6 comets)

I observed 6 comets visually on Jan. 31 in Mt. Hanadate, Ibaraki, Japan.

The weather was fine and clear, although Moon shined in the evening.

C/2017 T2 ( PanSTARRS )

9.0 mag   Dia. 5.5'   DC 6   (40.0-cm reflector 36x)

Strongly condensed and bright! It looked within the same field with Double Clusters h and chi in Perseus. The view was excellent.

C/2018 N2 ( ASASSN )

12.5 mag   Dia. 0.7'   DC 3-4   (40.0-cm reflector 144x)

It located near by a star.

C/2019 Y1 ( ATLAS )

11.4 mag   Dia. 1.4'   DC 3-4   (40.0-cm reflector 144x)

I could see another fragment of C/1988 A1 ( Liller ), in addition to C/1996 Q1 ( Tabur ), C/2015 F3 ( SWAN ). Very bright. Easy to find because it located near by Venus.

C/2020 A2 ( Iwamoto )

10.9 mag   Dia. 2.8'   DC 4-5   (40.0-cm reflector 75x)

Very bright! I was surprised that it looked so easily.

114P/Wiseman-Skiff

14.0 mag   Dia. 0.5'   DC 4   (40.0-cm reflector 257x)

Small. Near limit.

289P/Blanpain

fainter than 14.7 mag   Dia. 0.3'   (40.0-cm reflector 257x)

Passing only 0.17 a.u. from Earth. I expected its outburst. But actually, no outburst.

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Go to Seiichi Yoshida's Diary of Comet Observations in 2019.

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