Seiichi Yoshida's Diary of Comet Observations (2017)

Japanese version
Home page
Updated on February 7, 2017


Detailed observation data in ICQ format.


* 2017 Feb. 6 (5 comets)

I observed 5 comets visually on Feb. 6 in Mt. Hanadate, Ibaraki, Japan.

I wanted to observe 45P approaching to the earth before full moon.

C/2015 ER61 ( PanSTARRS )

11.4 mag   Dia. 1.2'   DC 3   (40.0-cm reflector 144x)

Diffuse, but well visible.

C/2015 V2 ( Johnson )

11.6 mag   Dia. 2.5'   DC 6-7   Tail 4.5' (p.a. 310 deg)   (40.0-cm reflector 75x)

Fairly bright. Looks nice with a tail.

I felt it became much brighter than January. But my measurement became similar to that in January.


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

Well visible. I felt it became much brighter than January. But my measurement became similar to that in January.


7.9 mag   Dia. 11'   DC 1   (40.0-cm reflector 36x)

6.9 mag   Dia. 16'   DC 2   (10x70 monocular)

Very bright and easy to see with a small monocular. Diffuse and very very large.

73P/Schwassmann-Wachmann 3

fainter than 12.2 mag   Dia. 1.1'   (40.0-cm reflector 144x)

Not visible.

When guideing my telescope to the comet, I found a bright nebula not recorded in my chart, where I plotted clusters and nebulae down to 12 mag. So I imagined it might be a fragment or new comet. But actually, it was planetary nebula NGC 6445.

* 2017 Jan. 24 (9 comets)

I observed 9 comets visually on Jan. 24 in Mt. Hanadate, Ibaraki, Japan.

Although the sky was covered with heavy clouds in day time, it became completely fine rapidly after the sunset, then it kept fine with no clouds all night. The moon with earthshine in the morning sky was very beautiful.

C/2015 ER61 ( PanSTARRS )

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

Much fainter and harder to see than expected, probably due to the low sky condition.

C/2015 V2 ( Johnson )

11.9 mag   Dia. 1.7'   DC 6-7   (40.0-cm reflector 75x)

Very strongly condensed and easy to see. Because it located very near by a 11-mag star, maybe the outer coma was not visible.


12.2 mag   Dia. 1.7'   DC 1-2   (40.0-cm reflector 144x)



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

Already visible visually. Small.


13.6 mag   Dia. 0.6'   DC 2-3   (40.0-cm reflector 144x)

Unexpectedly still visible. Near by a globular cluster M68.

73P/Schwassmann-Wachmann 3

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

Unexpectedly, already visible visually.

93P/Lovas 1

fainter than 13.5 mag   Dia. 0.8'   (40.0-cm reflector 257x)

Not visible.


13.9 mag   Dia. 0.9'   DC 2-3   (40.0-cm reflector 257x)

Unexpectedly still visible.


14.0 mag   Dia. 0.3'   DC 2   (40.0-cm reflector 257x)

Extremely hard to see.


Go to Seiichi Yoshida's Diary of Comet Observations in 2016.


Copyright(C) Seiichi Yoshida ( All rights reserved.