Seiichi Yoshida's Diary of Comet Observations (2016)

Japanese version
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Updated on June 6, 2016

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Detailed observation data in ICQ format.

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* 2016 June 3 (7 comets)

I observed 7 comets visually on June 3 in Kita-karuizawa, Gunma, Japan.

Almost cloudy in the evening, so I observed comets through small gaps of clouds. The clouds went away after 21:30(JST). But the sky was covered with thin clouds all night, so the sky condition was not good.

C/2013 X1 ( PanSTARRS )

7.9 mag   Dia. 7'   DC 5   (40.0-cm reflector 36x)

Hard to guide my telescope due to clouds, and the sky was getting brighter and brighter. The comet is very bright and large.

C/2014 S2 ( PanSTARRS )

11.8 mag   Dia. 2.3'   DC 4   (40.0-cm reflector 75x)

It became fainter rapidly during one month.

C/2014 W2 ( PanSTARRS )

13.1 mag   Dia. 1.6'   DC 6   (40.0-cm reflector 144x)

Strongly condensed and easy to see as before.

C/2015 WZ ( PanSTARRS )

fainter than 12.4 mag   Dia. 1.4'   (40.0-cm reflector 144x)

Unexpectedly, not visible. It overlapped on background stars at first, so I kept viewing for 20 minutes and waited until the comet moved. But anyway, it was not visible.

9P/Tempel 1

13.0 mag   Dia. 0.9'   DC 4   (40.0-cm reflector 144x)

It became much brighter, and easy to see.

116P/Wild 4

fainter than 13.1 mag   Dia. 1.1'   (40.0-cm reflector 257x)

Not visible, probably due to the bad sky condition.

252P/LINEAR

fainter than 12.5 mag   Dia. 1.6'   (40.0-cm reflector 144x)

As already reported by Yoshimoto and Harikae, the comet seems to have fade rapidly. Unexpectedly, I could not see the comet even with 0.40-m reflector.

Because the comet located in the dense region of faint background stars, I tried to see a moving diffuse comet for totally 30 minutes both with 75x and 144x magnification. However, the comet was not visible.

* 2016 May 1-4 (11 comets)

I observed 11 comets visually between May 1-4 in Kita-karuizawa, Gunma, Japan.

On May 1, many clouds existed in the evening. Especially the northern sky was cloudy. The whole sky became cloudy after 21:30. It became fine at midnight. But it became cloudy again in the morning, only Moon and few stars were visible.

On May 2, it was humid. The sky was covered by fog after 21:10.

On May 4, it was completely fine with no clouds in daytime after heavy rain, but suddenly it became cloudy in the evening. I could observe comets through large gaps of clouds, although it became weakly rainy in short time during my observation. It became completely cloudy after 21:20, but it became completely fine in the morning.

C/2013 US10 ( Catalina )

May 2   11.6 mag   Dia. 1.6'   DC 2   (40.0-cm reflector 144x)

May 4   11.9 mag   Dia. 1.4'   DC 2   (40.0-cm reflector 144x)

Unexpectedly, it looks bright still now.

C/2013 X1 ( PanSTARRS )

May 4   7.9 mag   Dia. 5'   DC 5   (40.0-cm reflector 36x)

Bright. It looks like a globular cluster.

C/2014 S2 ( PanSTARRS )

May 1   10.3 mag   Dia. 5.0'   DC 7   (40.0-cm reflector 36x)

May 2   10.2 mag   Dia. 6'   DC 6   (40.0-cm reflector 36x)

May 4   10.0 mag   Dia. 6'   DC 5   (40.0-cm reflector 36x)

Strongly condensed and easy to see as before.

C/2014 W2 ( PanSTARRS )

May 1   13.1 mag   Dia. 1.0'   DC 6-7   (40.0-cm reflector 144x)

May 2   12.2 mag   Dia. 1.3'   DC 6   (40.0-cm reflector 144x)

May 4   13.0 mag   Dia. 0.9'   DC 6   (40.0-cm reflector 144x)

Strongly condensed and easy to see as before.

C/2015 WZ ( PanSTARRS )

May 4   12.5 mag   Dia. 1.5'   DC 0-1   (40.0-cm reflector 144x)

Extremely diffuse.

9P/Tempel 1

May 1   14.6 mag   Dia. 0.4'   DC 3   (40.0-cm reflector 257x)

May 2   13.9 mag   Dia. 0.8'   DC 1-2   (40.0-cm reflector 257x)

May 4   13.8 mag   Dia. 1.1'   DC 3   (40.0-cm reflector 144x)

On May 1, I think I underestimated because it located near by a star. On May 2, the sky condition was good. It looks bright, but diffuse and fainter than expected. On May 4, it looks somewhat brighter.

77P/Longmore

May 1   14.4 mag   Dia. 0.5'   DC 3   (40.0-cm reflector 257x)

May 2   13.4 mag   Dia. 0.7'   DC 3   (40.0-cm reflector 257x)

Near by Sombrero Galaxy M104, whose dark band looks impressive. On May 2, the sky condition was good and it looked brighter.

81P/Wild 2

May 1   11.9 mag   Dia. 1.2'   DC 3   (40.0-cm reflector 144x)

May 2   11.6 mag   Dia. 1.9'   DC 2-3   (40.0-cm reflector 144x)

May 4   12.0 mag   Dia. 1.0'   DC 3   (40.0-cm reflector 144x)

Diffuse. On May 2, the sky condition was good and it was easy to see.

104P/Kowal 2

May 4   13.1 mag   Dia. 0.5'   DC 3   (40.0-cm reflector 257x)

Small.

116P/Wild 4

May 1   13.0 mag   Dia. 0.9'   DC 3   (40.0-cm reflector 257x)

May 4   13.7 mag   Dia. 0.8'   DC 3   (40.0-cm reflector 257x)

Well visible, better than expected.

252P/LINEAR

May 1   8.9 mag   Dia. 9'   DC 2   (40.0-cm reflector 36x)

May 1   7.9 mag   Dia. 14'   DC 1   (10x70 monocular)

May 4   7.9 mag   Dia. 16'   DC 1   (10x70 monocular)

May 4   8.5 mag   Dia. 10'   DC 3   (40.0-cm reflector 36x)

It became faint, but bright and large still now.

* 2016 Apr. 15 (5 comets)

I observed 5 comets visually on Apr. 15 in Mt. Hanadate, Ibaraki, Japan.

Because I wonder 252P/LINEAR may fade out rapidly soon, I went observe it again before full moon.

I also tried to observe 77P but I could not see it, because it was already low at the moon set.

C/2014 S2 ( PanSTARRS )

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

It looks strongly condensed DC=7 with 75x magnification.

C/2014 W2 ( PanSTARRS )

12.8 mag   Dia. 1.5'   DC 6   (40.0-cm reflector 144x)

Bright, strongly condensed, and easy to see.

9P/Tempel 1

14.0 mag   Dia. 0.5'   DC 3   (40.0-cm reflector 257x)

Near limit.

116P/Wild 4

13.4 mag   Dia. 0.6'   DC 2-3   (40.0-cm reflector 257x)

Near limit.

252P/LINEAR

6.3 mag   Dia. 30'   DC 3   (10x70 monocular)

Still bright and easy to see. I felt it became slightly fainter and smaller than last week. But my measurement became same as last week. I enjoyed the rendezvous with an open cluster IC 4665.

* 2016 Apr. 8-9 (7 comets)

I observed 7 comets visually on Apr. 8-9 in Mt. Hanadate, Ibaraki, Japan.

Finally I could see Comet 252P/LINEAR, passing near by the earth and bright as a naked comet.

Cherry blossoms are in full bloom in Mt. Hanadate.

C/2014 S2 ( PanSTARRS )

Apr. 8   9.9 mag   Dia. 4.5'   DC 6   (40.0-cm reflector 36x)

Apr. 9   9.9 mag   Dia. 5.5'   DC 6   (40.0-cm reflector 36x)

Well condensed, bright and easy to see.

C/2014 W2 ( PanSTARRS )

Apr. 8   12.2 mag   Dia. 1.2'   DC 6   (40.0-cm reflector 144x)

Small, but strongly condensed and easy to see.

9P/Tempel 1

Apr. 8   14.4 mag   Dia. 0.3'   DC 3-4   (40.0-cm reflector 257x)

Still faint.

77P/Longmore

Apr. 8   14.6 mag   Dia. 0.5'   DC 3   (40.0-cm reflector 257x)

Faint, but clearly visible than expected.

81P/Wild 2

Apr. 9   11.7 mag   Dia. 1.3'   DC 2   (40.0-cm reflector 144x)

Hard to see due to the thin clouds. It located near by an open cluster M35.

116P/Wild 4

Apr. 8   13.8 mag   Dia. 0.5'   DC 2   (40.0-cm reflector 257x)

Very hard to see probably due to the low sky haze. It located near by delta Sco.

252P/LINEAR

Apr. 8   6.3 mag   Dia. 30'   DC 3   (10x70 monocular)

Extremely large. Diffuse, but easy to see.

* 2016 Mar. 22 (5 comets)

I observed 5 comets visually on Mar. 22 in Mt. Hanadate, Ibaraki, Japan.

Comet 252P/LINEAR is passing near by the earth and bright as a naked eye comet in the Southern Hemisphere. Today is the closest approach of its fragment P/2016 BA14 ( PanSTARRS ) to the earth. So I tried to observe it despite of full moon.

Many clouds existed in the afternoon. But the weather became fine with no clouds at night. The sky transparency was not good.

C/2013 US10 ( Catalina )

9.7 mag   Dia. 2.2'   DC 1   (40.0-cm reflector 144x)

Diffuse and hard to see due to the strong moonlight. It located near by an open cluster NGC 1528.

C/2014 S2 ( PanSTARRS )

9.1 mag   Dia. 2.5'   DC 5   (40.0-cm reflector 144x)

Strongly condensed, bright and easy to see despite of the strong moonlight.

P/2016 BA14 ( PanSTARRS )

13.0 mag   DC ?   (40.0-cm reflector 257x)

Only several hours after the closest approach to the earth. It moved among stars very fast.

Because it located very near by the full moon and the backgroudn sky was so bright, I waited until the comet passed near by bright landmark stars. I wondered if I could not see it due to the strong moonlight, but I was lucky and I could see it. Motion was confirmed during 20 minutes.

The sky condition was bad and background faint stars looked somewhat fuzzy. So I could not confirm if the comet looked stellar or cometary.

81P/Wild 2

fainter than 12.5 mag   Dia. 0.9'   (40.0-cm reflector 257x)

Not visible due to the strong moonlight. It located near by Crab Nebula, but I could not enjoy the rendezvous.

333P/LINEAR

12.0 mag   Dia. 1.0'   DC 2   (40.0-cm reflector 144x)

Hard to see due to the strong moonlight. It located near by Pleiades, so easy to guide the telescope.

* 2016 Jan. 9 (9 comets)

I observed 9 comets visually on Jan. 9 in Mt. Hanadate, Ibaraki, Japan.

The weather was completely fine with no clouds in the evening and in the morning. But it was cloudy around mid night, with slight snow. The sky was not so clear. I could not see the Milky Way.

In the morning eastern sky, Venus and Saturn encounters very close.

I also tried to observe 22P and 10P. But 22P was not visible due to the bright background low sky. 10P was not visible because too close to 12-mag and 13-mag stars.

C/2013 US10 ( Catalina )

7.0 mag   Dia. 11'   DC 6   Tail 24' (p.a. 185 deg)   (40.0-cm reflector 36x)

6.4 mag   Dia. 17'   DC 6   (10x70 monocular)

Very bright and large. It looks fan shaped.

C/2013 X1 ( PanSTARRS )

8.6 mag   Dia. 7'   DC 6   (40.0-cm reflector 36x)

Very bright and large.

C/2014 S2 ( PanSTARRS )

10.0 mag   Dia. 2.5'   DC 7   (40.0-cm reflector 75x)

Sharp central condensation. It looks small, probably because it located near by a 7-mag star.

C/2014 W2 ( PanSTARRS )

12.4 mag   Dia. 0.9'   DC 3-4   (40.0-cm reflector 144x)

More difficult to see than expected.

C/2014 W11 ( PanSTARRS )

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

Not visible.

C/2015 X8 ( NEOWISE )

12.7 mag   Dia. 1.3'   DC 0   (40.0-cm reflector 144x)

Completely diffuse with no central condensation.

116P/Wild 4

13.3 mag   Dia. 0.7'   DC 3   (40.0-cm reflector 257x)

Also visible with 144x magnification.

230P/LINEAR

13.9 mag   Dia. 0.6'   DC 4   (40.0-cm reflector 257x)

I could see it in a very short time because clouds covered the sky.

249P/LINEAR

fainter than 13.0 mag   Dia. 0.4'   (40.0-cm reflector 257x)

Not visible.

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Go to Seiichi Yoshida's Diary of Comet Observations in 2015.

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