Seiichi Yoshida's Diary of Comet Observations (2004)

Japanese version Home page

Updated on May 9, 2006

Go to Seiichi Yoshida's Diary of Comet Observations in 2005.

2004 Dec. 30-31 (1 comet) I observed C/2004 Q2 visually on Dec. 30 and 31 beside Tsurumi River in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) Dec. 30   3.7 mag   Dia. 24'   DC 7   (10x70 monocular) Dec. 31   3.7 mag   Dia. 24'   DC 7   (10x70 monocular)

2004 Dec. 27-29 (1 comet) I observed C/2004 Q2 visually on Dec. 27 and 29 beside Tsurumi River and in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) Dec. 27   3.8 mag   Dia. 18'   DC 7   (10x70 monocular) Dec. 29   3.9 mag   Dia. 26'   DC 7   (10x70 monocular)

2004 Dec. 22-25 (1 comet) I observed C/2004 Q2 visually on Dec. 22 and 25 in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) Dec. 22   3.8 mag   Dia. 20'   DC 7   (10x70 monocular) Dec. 25   3.9 mag   Dia. 16'   DC 6-7   (10x70 monocular)

2004 Dec. 16-20 (1 comet) I observed C/2004 Q2 visually on Dec. 16 and 20 in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) Dec. 16   4.5 mag   Dia. 16'   DC 6   (10x70 monocular) Dec. 20   4.1 mag   Dia. 18'   DC 6   (10x70 monocular)

2004 Dec. 11 (13 comets + 2 asteroids) I observed 13 comets and 2 peculiar asteroids visually on Dec. 11 in Kita-karuizawa, Gunma, Japan. C/2001 Q4 ( NEAT ) about 12.3 mag   Dia. 1.8'   DC 2   (40.0-cm reflector 144x) Very faint and diffused. Inaccureate because overlapping on a 13.70-mag star. C/2002 T7 ( LINEAR ) 14.0 mag   Dia. 0.7'   DC 3   (40.0-cm reflector 144x) Faint and small. C/2003 T4 ( LINEAR ) 11.5 mag   Dia. 1.5'   DC 4   (40.0-cm reflector 144x) Bright, but not condensed so strongly. C/2004 Q1 ( Tucker ) 10.9 mag   Dia. 2.0'   DC 7   (40.0-cm reflector 75x) Getting fainter a bit, but still strongly condensed, wide and bright. C/2004 Q2 ( Machholz ) 4.3 mag   Dia. 20'   DC 7   (naked eye) 4.8 mag   Dia. 17'   DC 6   (10x70 monocular) Easily visible, looking nebulous, with the naked eye. C/2004 U1 ( LINEAR ) 13.4 mag   Dia. 0.9'   DC 3   (40.0-cm reflector 144x) Bright in outburst. 29P/Schwassmann-Wachmann 1 13.0 mag   Dia. 1.6'   DC 1   (40.0-cm reflector 144x) Very wide and completely diffused. Probably a remnant of very old outburst. But clearly visible with a large telescope. 32P/Comas Sola 12.8 mag   Dia. 1.3'   DC 5   (40.0-cm reflector 144x) Moderately condensed. Near by a bright star. 62P/Tsuchinshan 1 11.8 mag   Dia. 2.4'   DC 2   (40.0-cm reflector 144x) Very wide and diffused. Much brighter than November, and easy to see with a large telescope. 69P/Taylor fainter than 13.5 mag   Dia. 1.0'   (40.0-cm reflector 144x) Not visible yet. 78P/Gehrels 2 11.2 mag   Dia. 1.9'   DC 7   (40.0-cm reflector 75x) Getting fainter a bit, but still strongly condensed. 121P/Shoemaker-Holt 2 fainter than 13.6 mag   Dia. 1.2'   (40.0-cm reflector 144x) Not visible yet. 162P/Siding Spring fainter than 14.5 mag   (40.0-cm reflector 144x) Already too faint to see. They say it looks stellar, so I estimated the limiting magnitude of stars in focus. (944) Hidalgo 14.2 mag   DC 9   (40.0-cm reflector 144x) Getting faint. (3200) Phaethon 14.4 mag   DC 9   (40.0-cm reflector 144x) Maybe brighter than the ephemeris.

2004 Dec. 10 (1 comet) I observed C/2004 Q2 visually on Dec. 10 in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) 4.5 mag   Dia. 18'   DC 5-6   (10x70 monocular)

2004 Dec. 6-7 (1 comet) I observed C/2004 Q2 visually on Dec. 6 and 7 in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) Dec. 6   4.9 mag   Dia. 12'   DC 5   (10x70 monocular) Dec. 7   4.7 mag   Dia. 12'   DC 5-6   (10x70 monocular)

2004 Dec. 5 (1 comet) I observed C/2004 Q2 visually on Dec. 5 in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) 4.8 mag   Dia. 15'   DC 6   (10x70 monocular) Finally it becomes brighter than 5 mag now!

2004 Dec. 1-2 (1 comet) I observed C/2004 Q2 visually on Dec. 1 and 2 in my bedroom in Yokohama City, Kanagawa, Japan. C/2004 Q2 ( Machholz ) Dec. 1   5.0 mag   Dia. 11'   DC 4   (10x70 monocular) Dec. 2   5.2 mag   Dia. 13'   DC 5   (10x70 monocular) In the very bad city light.

2004 Nov. 9 (12 comets + 1 asteroid) I observed 12 comets and 1 asteroid visually on Nov. 9 in Kita-karuizawa, Gunma, Japan. Rendezvous of Moon, Venus and Jupiter was excellent view in the morning sky. C/2001 Q4 ( NEAT ) 12.8 mag   Dia. 1.2'   DC 2   (40.0-cm reflector 144x) Very diffused, although the central condensation is still visible. C/2003 K4 ( LINEAR ) 7.0 mag   Dia. 4.4'   DC 6-7   (40.0-cm reflector 36x) Well condensed and easy object in the low sky, although fainter than expected. C/2003 T3 ( Tabur ) fainter than 13.6 mag   Dia. 0.7'   (40.0-cm reflector 144x) Became invisible. C/2003 T4 ( LINEAR ) 12.7 mag   Dia. 1.0'   DC 3   (40.0-cm reflector 144x) It seems to have brightened slightly. But not easy to see because locating low still now. C/2004 Q1 ( Tucker ) 9.8 mag   Dia. 4.2'   DC 6   (40.0-cm reflector 36x) Bright and large. C/2004 Q2 ( Machholz ) 7.0 mag   Dia. 10'   DC 4   (10x70 monocular) Brightened furthermore. Now it is easy to see with binoculars. P/2004 T1 ( LINEAR-NEAT ) fainter than 13.8 mag   Dia. 0.6'   (40.0-cm reflector 144x) Became invisible. 29P/Schwassmann-Wachmann 1 12.9 mag   Dia. 1.1'   DC s4   (40.0-cm reflector 144x) Faint stellar nucleus is visible, surrounded with a coma of DC=4. 32P/Comas Sola 13.4 mag   Dia. 0.9'   DC 5   (40.0-cm reflector 144x) Already bright, easy object with a large telescope. 62P/Tsuchinshan 1 13.8 mag   Dia. 2.0'   DC 1-2   (40.0-cm reflector 144x) Extremely diffused. 78P/Gehrels 2 10.3 mag   Dia. 2.1'   DC 6   Tail 4.2' (p.a. 255 deg)   (40.0-cm reflector 36x) Brightened furthermore. The head became round and large. The sharpness is weakened, on the other hand, it becamse soft. 88P/Howell fainter than 13.1 mag   Dia. 0.6'   (40.0-cm reflector 144x) It must be fainter than 14 mag, so my observation is not significant. (944) Hidalgo 13.2 mag   DC 9   (40.0-cm reflector 144x) Still bright. Stellar.

2004 Oct. 15 (10 comets + 1 asteroid) I observed 10 comets visually on Oct. 15 in Kita-karuizawa, Gunma, Japan. C/2001 HT50 ( LINEAR-NEAT ) fainter than 13.7 mag   Dia. 0.7'   (40.0-cm reflector 144x) Not visible again. I gave it up. C/2001 Q4 ( NEAT ) 11.4 mag   Dia. 1.7'   DC 3-4   (40.0-cm reflector 75x) Still bright enough. But it became more diffused. C/2003 T4 ( LINEAR ) about 13.7 mag   Dia. 0.8'   DC 5   (40.0-cm reflector 144x) Still faint. C/2004 Q1 ( Tucker ) 10.2 mag   Dia. 1.9'   DC 6-7   Tail 4' (p.a. 190 deg)   (40.0-cm reflector 75x) Became very bright. It has a wide tail and looks beautiful, although the tail is very faint. C/2004 Q2 ( Machholz ) 8.1 mag   Dia. 6.5'   DC 6   (40.0-cm reflector 36x) Already very large and bright. It seems to have a tail. P/2004 T1 ( LINEAR-NEAT ) 13.3 mag   Dia. 0.8'   DC 3   (40.0-cm reflector 144x) Visible visually. It is small. 29P/Schwassmann-Wachmann 1 11.7 mag   Dia. 1.5'   DC 2   (40.0-cm reflector 144x) Easy to see. Probably several days after an outburst because it was diffused without condensation, like a cloud. 32P/Comas Sola 14.0 mag   Dia. 0.9'   DC 6   (40.0-cm reflector 144x) Already visible visually. 78P/Gehrels 2 11.0 mag   Dia. 1.1'   DC 7   Tail 1.7' (p.a. 260 deg)   (40.0-cm reflector 75x) Strongly condensed and has a evident tail. 88P/Howell 14.1 mag   Dia. 0.9'   DC 2   (40.0-cm reflector 144x) A very hard object. It is very faint. (944) Hidalgo 13.2 mag   DC 9   (40.0-cm reflector 144x) Completely stellar. Already bright and easy to see.

2004 Sept. 17 (7 comets) I observed 7 comets visually on Sept. 17 in Kita-karuizawa, Gunma, Japan. C/2001 HT50 ( LINEAR-NEAT ) fainter than 13.8 mag   Dia. 0.4'   (40.0-cm reflector 144x) At opposition, but not visible. Interfered with a 13.9-mag star locating near by the comet position. C/2001 Q4 ( NEAT ) 10.7 mag   Dia. 1.1'   DC 6   (40.0-cm reflector 144x) Bright and clearly visible still now. C/2003 T3 ( Tabur ) 12.1 mag   Dia. 0.7'   DC 2   (40.0-cm reflector 144x) Still visible. It has a smooth flat face without condensation. It looks similar to that in June, though it is much faint now. C/2004 Q1 ( Tucker ) 11.8 mag   Dia. 1.7'   DC 6-7   (40.0-cm reflector 144x) New comet. Bright, well condensed and easy to see. C/2004 Q2 ( Machholz ) 9.8 mag   Dia. 2.5'   DC 6-7   (40.0-cm reflector 75x) New comet. Very bright, large, well condensed and easy to see. 29P/Schwassmann-Wachmann 1 12.1 mag   DC 8-9   (40.0-cm reflector 144x) Now in a new outburst! It looks almost stellar and bright. In fact, when I viewed it at first, it misunderstood as if it were one of the background stars. So I waited until it moves and tried to view it again later. Then I found that the "star" was slightly cometary. Yes, it is indeed a comet 29P, just at the beginning of an outburst. 78P/Gehrels 2 11.7 mag   Dia. 1.1'   DC 7   Tail 1.7' (p.a. 240 deg)   (40.0-cm reflector 144x) Bright. The tail is clearly visible.

2004 Aug. 21 (2 comets) I observed 78P and 88P visually on Aug. 21 in Kita-karuizawa, Gunma, Japan. 78P/Gehrels 2 12.4 mag   Dia. 1.1'   DC 5-6   (40.0-cm reflector 144x) Already bright. It is well condensed and easy to see. 88P/Howell 14.1 mag   Dia. 1.4'   DC 3   (40.0-cm reflector 144x) Already very faint. It is diffused and hard to see. No motion was confirmed.

2004 Aug. 20 (3 comets) I observed C/2001 Q4, C/2003 K4 and C/2004 H6 visually on Aug. 20 in Mt. Tsukuba, Ibaraki, Japan. C/2001 Q4 ( NEAT ) 9.4 mag   Dia. 2.3'   DC 6   (40.0-cm reflector 75x) Small, but well condensed and easy to see. C/2003 K4 ( LINEAR ) 7.1 mag   Dia. 3.1'   DC 7   (40.0-cm reflector 75x) Looks like a typical comet. Well condensed and easy to see. C/2004 H6 ( SWAN ) 12.3 mag   Dia. 1.6'   DC 1   (40.0-cm reflector 144x) Extremely diffused and hard to see. No motion was confirmed.

2004 June 15 (2 comets) I observed C/2001 Q4 and C/2003 K4 visually on June 15 in Fujishiro-machi, Ibaraki, Japan. C/2001 Q4 ( NEAT ) 6.8 mag   Dia. 7'   DC 7   (40.0-cm reflector 36x) Now it looks as a normal comet. C/2003 K4 ( LINEAR ) 8.7 mag   Dia. 3.2'   DC 7   (40.0-cm reflector 75x) The stellar nucleus had been evident and the surrounding coma had been very faint before. However, the surrounding coma became also brighter, and now it looks like a typical comet. It is also DC=7, but looks very different from C/2001 Q4.

2004 June 4 (2 comets) I observed C/2003 K4 and C/2003 T3 visually on June 4 in Mt. Tsukuba, Ibaraki, Japan. I also tried to observe C/2004 F4. But I found a star exist at that position... C/2003 K4 ( LINEAR ) 9.2 mag   Dia. 3.5'   DC s6   (40.0-cm reflector 75x) I felt that the nucleus was weaker than the previous day. I mean, it was not star-like, but was strongly condensed as a comet. It was surrounded by a large diffused coma, so it was beautiful. C/2003 T3 ( Tabur ) 9.4 mag   Dia. 2.2'   DC 3   (40.0-cm reflector 144x) Diffused, but clearly visible. It was near by alpha Per, so easy to find.

2004 June 3 (1 comet) I observed C/2003 K4 visually on June 3 in Fujishiro-machi, Ibaraki, Japan. C/2003 K4 ( LINEAR ) 9.2 mag   Dia. 2.0'   DC S4   (40.0-cm reflector 75x) Due to bad weather in May, I could observe it since late April. It became surprisingly large and bright while last one month. It looks different from that in April. It was strongly condensed but evidently different from a star in April. However, now it has a star-like necleus with diffused coma surrounding the nucleus.

2004 May 21 (1 comet) I observed C/2001 Q4 visually on May 21 in Mt. Tsukuba, Ibaraki, Japan. C/2001 Q4 ( NEAT ) 4.8 mag   Dia. 12'   DC 7   Tail 0.4 deg (p.a. 100 deg)   (20x125 binoculars) Excellent view with 20x125 binoculars! Strongly condensed and very large, so I estimated the magnitude in M-method. Maybe two tails are visible, but very faint and short. The comet seems to have faded slightly.

2004 May 11 (1 comet) I observed C/2001 Q4 visually on May 11 in Fujishiro-machi, Ibaraki, Japan. The sky was badly hazy with city light pollution. I could see only 1-mag stars with naked eyes. C/2001 Q4 looked poor. On the other hand, I enjoyed Venus and Saturn :-) C/2001 Q4 ( NEAT ) 3.4 mag   Dia. 13'   DC 6-7   (5-cm refractor 10x) Looked poor. Comet Ikeya-Zhang, it also became 3-4 mag in the evening sky, looked fantastic with shining necleus and straight tail. But C/2001 Q4 looked dim ball with no tail, so it impressed much fainter. With 0.40-m telescope, it had a 10-mag stellar nucleus with faint coma, but that's all. Not so impressive.

2004 Apr. 29 (2 comets) I observed C/2003 K4 and C/2004 F4 visually on Apr. 29 in Yasato-machi, Ibaraki, Japan. C/2003 K4 ( LINEAR ) 11.1 mag   Dia. 1.1'   DC 7   (40.0-cm reflector 144x) It becomes slightly brighter and slightly larger, still well condensed. C/2004 F4 ( Bradfield ) about 6 mag   DC 6   (11x80 binoculars) I could see it in the fog, but it was too hard to observe it and estimate the magnitude. It was roughly about 6 mag.

2004 Apr. 16 (1 comet) I observed C/2003 K4 visually on Apr. 16 in Mt. Tsukuba, Ibaraki, Japan. C/2003 K4 ( LINEAR ) 11.2 mag   Dia. 0.8'   DC 6   (40.0-cm reflector 144x) Getting brighter. But the shape is similar to before, small, condensed and easy to see.

2004 Apr. 2 (1 comet) I observed C/2003 K4 visually on Apr. 2 in Mt. Tsukuba, Ibaraki, Japan. C/2003 K4 ( LINEAR ) 11.7 mag   Dia. 1.0'   DC 6   (40.0-cm reflector 144x) Looks similar to that in late February. It is small and condensed, easy to see. I enjoyed M71 and M27, too.

2004 Mar. 28 (1 comet) I observed C/2003 H1 visually on Mar. 28 in Mt. Tsukuba, Ibaraki, Japan. It became cloudy at dawn, so I could not observe C/2003 K4. C/2003 H1 ( LINEAR ) 11.8 mag   Dia. 1.2'   DC 3   (40.0-cm reflector 144x) Due to the moon light and dim sky, C/2003 H1 was not an easy object. I enjoyed Ghost of Jupiter (NGC 3242), too.

2004 Feb. 23 (3 comets) I observed 3 comets visually on Feb. 23, under a clear sky with no clouds, in Mt. Tsukuba, Ibaraki, Japan. C/2003 H1 ( LINEAR ) about 11.9 mag   Dia. 1.2'   DC 4   (40.0-cm reflector 144x) The observation became inaccurate due to a nearby 14.3 mag star. C/2003 K4 ( LINEAR ) 12.2 mag   Dia. 0.8'   DC 6-7   (40.0-cm reflector 144x) I was very surprised that C/2003 K4 was clearly and easily visible. It is already bright enough, strongly condensed. 123P/West-Hartley 13.7 mag   Dia. 1.0'   DC 4   (40.0-cm reflector 144x) Visible, but small and faint.

2004 Feb. 15 (5 comets) I observed 5 comets visually on Feb. 15 in Mt. Tsukuba, Ibaraki, Japan. Well, I bought a new 0.40-m reflector :-) C/2001 HT50 ( LINEAR-NEAT ) fainter than 12.0 mag   Dia. 0.8'   (40.0-cm reflector 144x) Not visible even using 0.40-m reflector, because it locates in the very dim sky with city light of Tokyo. C/2002 T7 ( LINEAR ) 7.2 mag   Dia. 6.5'   DC 5   (40.0-cm reflector 36x) It has kept almost the same brightness since January. It is low in the very dim sky with city light of Tokyo, so not a fantastic view at all. C/2003 H1 ( LINEAR ) 11.5 mag   Dia. 1.6'   DC 3   (40.0-cm reflector 144x) They say it is getting brighter. Yes, it is now bright enough. It is large with weak condensation, contrastive to C/2001 HT50 last autumn. 43P/Wolf-Harrington 12.0 mag   Dia. 1.1'   DC 2   (40.0-cm reflector 144x) Due to clouds, I could observe 43P when it becomes very low. So it was not easy to see. 123P/West-Hartley fainter than 13.4 mag   Dia. 1.0'   (40.0-cm reflector 144x) Not visible, although CCD observers reported it as around 14.5 mag.

2004 Feb. 7 (1 comet) I observed C/2002 T7 visually on Feb. 7 in Fujishiro-machi, Ibaraki, Japan. C/2002 T7 ( LINEAR ) 6.8 mag   Dia. 4'   DC 3   (25.4-cm Schmidt-Cassegrain 32x) I observed it under string light pollution, so it seemed faint and diffused.

2004 Jan. 31 (1 comet) I observed C/2002 T7 visually on Jan. 31 in Mt. Tsukuba, Ibaraki, Japan. C/2002 T7 ( LINEAR ) 7.4 mag   Dia. 5'   DC 4   (25.4-cm Schmidt-Cassegrain 32x) It was dim due to moon light.

2004 Jan. 23 (2 comets) I observed 2 comets visually on Jan. 23 in Mt. Tsukuba, Ibaraki, Japan. C/2002 T7 ( LINEAR ) 7.4 mag   Dia. 7.5'   DC 4   (25.4-cm Schmidt-Cassegrain 32x) It has a faint large coma. It looks very diffused. People can report it as DC=2 or so if they cannot see the center. Much different impression from that until December. However, the brightness is much brighter than the ephemeris. The Charles S. Morris's JPL web page notes the possible outburst on Jan. 23. However, I did not catch any hint of outburst. 43P/Wolf-Harrington 11.7 mag   Dia. 0.9'   DC 3   (25.4-cm Schmidt-Cassegrain 128x) Very small and faint, but not too hard to see.

2004 Jan. 15 (2 comets) I observed 2 comets visually on Jan. 15 in Mt. Tsukuba, Ibaraki, Japan. C/2002 T7 ( LINEAR ) 7.6 mag   Dia. 3.7'   DC 6   (25.4-cm Schmidt-Cassegrain 32x) Large and bright. It looked like C/1999 T1 at 7 mag in 2000 December. Now it is about 1 mag brighter than the ephemeris. 43P/Wolf-Harrington fainter than 12.0 mag   Dia. 1.1'   (25.4-cm Schmidt-Cassegrain 128x) Not seen.

Go to Seiichi Yoshida's Diary of Comet Observations in 2003.