Seiichi Yoshida's Diary of Comet Observations (2018)

Japanese version
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Updated on May 7, 2018

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Detailed observation data in ICQ format.

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* 2018 May 3-4 (4 comets)

I observed 4 comets and 1 nova visually on May 3-4 in Kita-karuizawa, Gunma, Japan.

In addition to 4 PanSTARRS's comets, I also observed a naked-eye nova discovered by Yuji Nakamura. The contrast of orange nova and a nearby blue star was beautiful.

V392 Per:
  May 3.50: 8.4 mag (S. Yoshida, Gunma, Japan, 0.40-m f/4.5 reflector);
  May 4.49: 8.7 mag (S. Yoshida, Gunma, Japan, 0.40-m f/4.5 reflector);

C/2015 O1 ( PanSTARRS )

May 3   13.5 mag   Dia. 0.8'   DC 4-5   (40.0-cm reflector 144x)

May 4   13.1 mag   Dia. 1.2'   DC 5   (40.0-cm reflector 144x)

Well condensed and easy to see.

C/2016 M1 ( PanSTARRS )

May 3   10.5 mag   Dia. 1.7'   DC 4   (40.0-cm reflector 144x)

Hard to see due to the bright moon.

C/2016 N6 ( PanSTARRS )

May 3   12.3 mag   Dia. 1.4'   DC 5   (40.0-cm reflector 144x)

May 4   12.7 mag   Dia. 1.1'   DC 5   (40.0-cm reflector 144x)

Well condensed and easy to see.

C/2016 R2 ( PanSTARRS )

May 3   13.1 mag   Dia. 0.9'   DC 3-4   (40.0-cm reflector 257x)

May 4   13.2 mag   Dia. 0.6'   DC 2   (40.0-cm reflector 257x)

It became faint, although it is at the perihelion now.

* 2018 Mar. 12 (4 comets)

I observed 4 comets visually on Mar. 12 in Mt. Hanadate, Ibaraki, Japan.

The weather was fine with no clouds in the evening, but the sky was dim.

The sky was covered with clouds in the morning. But I could observe only C/2015 O1 through a gap of clouds in short time.

C/2015 O1 ( PanSTARRS )

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

Bright, but the condensation is weaker than expected.

C/2016 N6 ( PanSTARRS )

12.7 mag   Dia. 1.1'   DC 6   (40.0-cm reflector 144x)

Small, strongly condensed, and easy to see.

C/2016 R2 ( PanSTARRS )

about 11.6 mag   Dia. 1.5'   DC 3   (40.0-cm reflector 75x)

Overlapping on a 12.8 mag star, so somewhat difficult to observe. But still bright and well visible.

185P/Petriew

about 12.5 mag   Dia. 1.3'   DC 1   (40.0-cm reflector 144x)

Hard to see because the background sky was very bright.

* 2018 Jan. 6 (2 comets)

I observed 2 comets visually on Jan. 6 in Mt. Hanadate, Ibaraki, Japan.

I also tried to observe C/2017 O1 passing near by an open cluster NGC 188. But I could not see the comet due to a nearby double star of 14.5 mag stars.

C/2016 R2 ( PanSTARRS )

11.1 mag   Dia. 2.6'   DC 5   (40.0-cm reflector 75x)

Bright. Near by Hyades.

C/2017 T1 ( Heinze )

10.3 mag   Dia. 4'   DC 1   (40.0-cm reflector 36x)

Bright, but very diffuse.

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