Seiichi Yoshida's Diary of Comet Observations (2006)

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Updated on October 9, 2007

Go to Seiichi Yoshida's Diary of Comet Observations in 2007.

2006 Dec. 22-23 (9 comets) I observed 9 comets visually on Dec. 22 and 23 in Kita-karuizawa, Gunma, Japan. Mt. Asama was decorated with snow, and the parking area was also covered with snow. The roads in the mountains were partially frozen. However, there was no snow around the observing area. On Dec. 22, the large clouds were about to go away in the evening. But actually, it was almost completely cloudy in the evening, and kept mostly cloudy for a while. I only could see stars through small fine spaces, but sometimes interrupted. Not so clear sky. However, after 22:30 local time, it turned to be fine. Then it kept clear fine sky until morning. The autumn and winter Milky Way became clear. But the temperature cooled down from 0 to -3 centigrade. Before dawn of the night, I could see many Ursids meteors in northern sky after I put away my telescope. I counted 7 meteors during about 7-8 minutes around 5:30 local time. It means HR=60 or so. So maybe it was an outburst of Ursids. On Dec. 23, the daytime fine sky kept after the sunset. I could see a beautiful thin Moon. However, many small clouds came after 20:00 local time. The sky was covered with clouds before mid night. A little snow fell. I also tried to observe C/2006 L1 ( Garradd ). But I brought a wrong chart based on the old orbital elements, and I failed to catch it. After I came back home, I found that the comet was about 40 arcmin off from my chart position. Then I understood why nothing was visible at my chart position. Because this comet brightened unexpectedly, I was possessed with a thought that the comet got diffuse and faded out suddenly. Therefore, I tried to find a diffuse object with larger magnification in the field. I did not try to search around the position. C/2003 WT42 ( LINEAR ) Dec. 22   14.2 mag   Dia. 0.7'   DC 4   (40.0-cm reflector 144x) It is half a year since my last observation. The comet became fainter, but it is still visible. It seems still well condensed, and not so difficult to catch. P/2006 HR30 ( Siding Spring ) Dec. 22   14.6 mag   DC 9   (40.0-cm reflector 257x) Dec. 23   14.6 mag   DC 9   (40.0-cm reflector 257x) Clearly visible with 40-cm telescope, but it is still faint as 14.6 mag. Hard to find it among so many faint stars in the Milky Way. Because the comet is faint, the GSC cannot help us enough. It looked completely same as nearby faint stars. so I decided it as DC=9. But it was too faint to determine if the object was exactly stellar with no cometary activity. C/2006 L2 ( McNaught ) Dec. 22   12.1 mag   Dia. 0.9'   DC 6   (40.0-cm reflector 144x) I could finally see it in the morning sky, although I could not see it when it located in the evening sky. Small, and moderately condensed. C/2006 M4 ( SWAN ) Dec. 23   9.4 mag   Dia. 5'   DC 3   (40.0-cm reflector 36x) It is two months since my last observation. The comet faded, but it is still bright, large and easy to see with 40-cm telescope. Large and diffuse. 4P/Faye Dec. 23   10.7 mag   Dia. 2.8'   DC 6   (40.0-cm reflector 75x) It got somewhat fainter, but it is still easy to see. It seems very diffuse with lower magnification. But the central condensation seems strong with higher magnification. I could not see it on Dec. 22 because overlapping on a 8.5 mag star. 29P/Schwassmann-Wachmann 1 Dec. 22   13.1 mag   Dia. 1.2'   DC 1-2   (40.0-cm reflector 144x) Dec. 23   fainter than 13.4 mag   Dia. 0.6'   (40.0-cm reflector 144x) Very faint, near limit, but I could see a faint diffuse object on Dec. 22. I could not see it on Dec. 23, maybe disturbed by a nearby 14.6 mag star. 76P/West-Kohoutek-Ikemura Dec. 22   fainter than 14.2 mag   Dia. 0.6'   (40.0-cm reflector 144x) Originally it was expected to reach to 13 mag. But actually, it was invisible. 84P/Giclas Dec. 23   14.1 mag   Dia. 0.6'   DC 4   (40.0-cm reflector 144x) I tried to observe it because Ken-ichi Kadota reported it as 14.8 mag on Dec. 13. I could see it visually, so the comet is actually bright. Not so difficult to catch. I could not observe it on Dec. 22 because overlapping on a 11.6 mag star. My observation on Dec. 23 was sometimes interrupted by clouds, but I could see the comet. 181P/Shoemaker-Levy 6 Dec. 23   fainter than 13.1 mag   Dia. 0.8'   (40.0-cm reflector 144x) Originally it was expected to reach to 13 mag. But actually, it was invisible.

2006 Oct. 31 (9 comets) I observed 9 comets visually on Oct. 31 in Kita-karuizawa, Gunma, Japan. The mountain trees turn red or yellow, so it is a beautiful sight. The sky was very hazy in the evening. Strongly influenced by the half moon, and the sky was bad as if in the city. I could not see the Milky Way. It was difficult to trace Hercules with my naked eyes. The sky was temporarily covered with clouds around 18:00, but became fine again around 18:30. Then it kept fine all night. At midnight, the sky became clear. Especially, after the moon set, many faint stars became visible. So did the Milky Way, of course. In the morning, the winter Milky Way and the zodiacal light were visible. After the morning glow began, some clouds visited suddenly. C/2005 E2 ( McNaught ) 14.2 mag   Dia. 0.6'   DC 3   (40.0-cm reflector 144x) Hardly visible, but a tiny faint one was visible. C/2005 YW ( LINEAR ) 13.7 mag   Dia. 0.5'   DC 3-4   (40.0-cm reflector 144x) Hardly visible, but a tiny faint one was visible. P/2006 HR30 ( Siding Spring ) 14.6 mag   DC 9   (40.0-cm reflector 257x) I heard the tail became visible again by CCD. So, I confirmed the comet visually, but no rapid brightening occured. It was still fainter than 14.5 mag. Due to the moon light and hazy sky, it was hard to see faint stars. It was uncertain whether it was completely stellar or slightly cometary. After I came back home, I found there must be a 14.5 mag star near by the comet position. But in the DSS image, the 14.5 mag data is actually a blended magnitude of faint two stars. So I judged I observed the comet. C/2006 L1 ( Garradd ) 9.8 mag   Dia. 5'   DC 3   (40.0-cm reflector 36x) I was very surprised, what a large object it was! Very bright and easy to see. The central bright part is larger than 4P/Faye, so I felt it was brighter than 4P. Unexpectedly, the condensation is weak, even with higher magnification. C/2006 M4 ( SWAN ) 5.3 mag   Dia. 13'   DC 7   (10x24 binoculars) 5.3 mag   Dia. 14'   DC 7   (10x70 monocular) My first observation after the outburst. They say it reached up to 4 mag, but it has already faded down to 5 mag. It was not excellent for me due to the hazy sky and the moon light. I could not see it with naked eyes. I could not see the tail. But the comet became much larger than my previous observation in early October. The central condensation is still strong with a 0.40-m reflector. It located near by Hercules Cluster M13. The comet's feature was similar to M13. But the condensation was somewhat stronger than M13, and the comet was much brighter than M13. Comet 73P/Schwassmann-Wachmann 3 has passed the same area just half a year ago. It was impressive that I observed another naked eye comet at the same area. P/2006 T1 ( Levy ) 11.6 mag   Dia. 1.1'   DC 3-4   (40.0-cm reflector 144x) I heard a rumor that it has been fading rapidly. So I thought it was already extremely diffuse and hard to see. But unexpectedly, it was still bright. It was still condensed. Many bright stars recorded in the GSC are faint galaxies in fact around this area. So it was difficult to determine the comet position. In the field, I could not see which star in the chart is a galaxy in fact. So, I was anxious that maybe I was observing a galaxy by mistake!? Because the comet looked much more condensed than expected, I could not be condident that I was really observing the comet, not a galaxy. 4P/Faye 9.8 mag   Dia. 3.9'   DC 7   (40.0-cm reflector 36x) Bright, strongly condensed, and easy to see. It became large, so the tail became unclear. 29P/Schwassmann-Wachmann 1 11.9 mag   Dia. 1.7'   DC 3   (40.0-cm reflector 144x) Brightest and largest among my recent observations of 29P! Wonderful looking. The central part is well condensed, surrounded with a large diffuse coma. Maciej Reszelski reported it as 13.2 mag on the same day. But in my view, it was much brighter. 177P/Barnard 2 12.2 mag   Dia. 1.2'   DC 1-2   (40.0-cm reflector 144x) Hard to see due to the moon light. It was still visible, but it became very small. Faint diffuse nebulous object. It located near by two 13.5 mag stars. I thought they did not interfere my estimation. But when I observe it again after the moon set, I felt it was much fainter. So maybe I overestimated it in this report.

2006 Oct. 9 (5 comets) I observed 5 comets visually on Oct. 9 in Kita-karuizawa, Gunma, Japan. We could have a clear fine sky for several days in Japan. Although the full moon shines, I went to observe comets, especially a new comet Levy, because it may be in outburst and may fade out soon. The weather forecast says it was rainy on Saturday and Sunday at the mountain location in Kita-Karuizawa, but it will be fine on Monday. Actually, the sky was clear and I could see mountain ridgelines far away clearly. But thin clouds expanded in the sky. In the evening, some parts of the sky was covered with clouds, especially the eastern and southern parts. But the western sky was fine. The full moon was hidden by clouds in the eastern sky for a while, and I could observe comets without strong moon light. After a while, the clouds moved away, and the full moon appeared. Then the sky became very bright immediately, and faint stars disappeared. In the morning, the sky was fine. I enjoyed the beautiful morning glow. I also tried to observe 4P/Faye. The comet was visible anyway. But it was impossible to estimate the magnitude because too close to the full moon. C/2006 L2 ( McNaught ) fainter than 11.3 mag   Dia. 1.0'   (40.0-cm reflector 144x) I tried to observe it again. It was extremely low in the evening, the background was bright, and the comet was invisible. I have to wait until winter when it appears in the morning sky. C/2006 M4 ( SWAN ) 6.1 mag   DC 8   (10x70 monocular) 6.3 mag   Dia. 5.5'   DC 7-8   (40.0-cm reflector 36x) I could see it both in the evening and morning. The area around the comet was covered by thin clouds in the evening, so it was impossible to estimate the magnitude. Although the comet was lower in the morning, I could observe it due to the fine sky. The comet was very similar to itself in September. It looked evidently cometary with 10x70 monocular in the evening when locating high. But in the morning, it looked almost stellar. C/2006 P1 ( McNaught ) about 12.5 mag   Dia. 1.4'   DC 2   (40.0-cm reflector 144x) Very low in the evening. The sky was not very clear and hard to see faint stars. But sometimes the sky became clear. Then I could see very faint stars, and a faint nebulous object, too. Maybe the comet is bright. But probably due to the thin clouds passing through the telescope field, I could not see the comet for a long time. The star chart around this area is very different between the GSC and ASAS-3. The DSS image suggests the GSC is right. So I report my observation using the GSC. P/2006 T1 ( Levy ) 10.5 mag   Dia. 1.7'   DC 3   (40.0-cm reflector 75x) Despite the full moon, the comet was bright and clearly visible. The central condensation was not strong, but not too weak. It was DC=3 with 75x magnification, but DC=4-5 with 144x magnification. 177P/Barnard 2 11.4 mag   Dia. 2.3'   DC 1-2   (40.0-cm reflector 75x) It seems to have been fading. But the large diffuse coma is still visible, and it is a bright enjoyable object still now. Although it was a large diffuse object, I could see a small central condensation clearly. The impression of the comet is "large and diffuse", but it is not easy to determine the DC value.

2006 Sept. 27 (11 comets) I observed 11 comets visually on Sept. 27 in Kita-karuizawa, Gunma, Japan. It was thunderstorm at noon in Tokyo. But the weather became fine in the evening in Gunma as forecasted. The weather was fine in the evening. But there were some clouds here and there, and they covered the sky sometimes. My observation was often interfered. Especially, a cloud existed in the southwest direction and disturbed obseravtions of evening low comets. In general, the northern and western sky was cloudy, but southern sky was fine. The sky was not so dark and not so clear, probably due to the humidity. Especially, the city light was intense in the eastern sky, as if it were just before the sunrise. Midnight, the sky became fine and clear with no clouds. Then the fine weather kept until the morning. I think I could see the North America Nebula with naked eyes. Maybe I just saw a dense part of the Milky Way. But I could see the famous shape of the North America. It was cloudy and sometimes rainy on Sept. 28 and 29. C/2005 E2 ( McNaught ) fainter than 13.3 mag   Dia. 0.4'   (40.0-cm reflector 257x) Maciej Reszelski reported it as 12.9 mag on Sept. 22. But I could not see the comet. P/2006 HR30 ( Siding Spring ) 14.9 mag   DC 9   (40.0-cm reflector 257x) I observed it and confirmed the motion in the evening. But I confirmed it again at midnight because the sky became clear with no clouds. The comet is still completely stellar and faint. It is moving among faint background stars in Cygnus, fainter than the limiting magnitude of the GSC. Maybe someone confuse one of the background stars with the comet by mistake? Many people reported it as 14 mag recently. But the comet is definitely fainter, around 15 mag. C/2006 L2 ( McNaught ) fainter than 11.5 mag   Dia. 1.3'   (40.0-cm reflector 144x) Unfortunately, there was a cloud in the low sky. The background sky was not dark due to the thin clouds, and the comet was not visible. C/2006 M4 ( SWAN ) 6.3 mag   Dia. 8'   DC 7-8   (5-cm refractor 10x) 6.4 mag   Dia. 6'   DC 7-8   (40.0-cm reflector 36x) I was surprised because the comet was very bright! Very strongly condensed. However, it looked cometary with a small guiding telescope. So it must have a large coma. Because there was a cluster of trees in the direction of the comet, I had to wait for a while after the morning glow began in order to observe the comet with my 40-cm telescope. So the background sky became somewhat bright. C/2006 P1 ( McNaught ) fainter than 11.9 mag   Dia. 1.1'   (40.0-cm reflector 144x) The comet was hidden by clouds when I observed C/2006 L2 in advance. When the comet appeared again, it was already low. They say it is extremely large and diffuse. The sky was not dark, so it was very hard to see a diffuse object. 4P/Faye 10.8 mag   Dia. 1.1'   DC 7-8   Tail 4' (p.a. 250 deg)   (40.0-cm reflector 75x) 10.8 mag   Dia. 2.8'   DC 7   (40.0-cm reflector 36x) Very bright! The tail is clear. It looks elegant like a photo image by Michael Jager and Gerald Rhemann. Very strongly condensed as before. The head seems small. But it seems much larger with a lower magnification, although the tail becomes unclear. 29P/Schwassmann-Wachmann 1 13.4 mag   Dia. 1.0'   DC 3   (40.0-cm reflector 144x) Clearly visible unexpectedly. But the condensation was weak. When the last outburst occured? In this year, it seems alwasy visible at 13 mag independent on outbursts. 71P/Clark 12.6 mag   Dia. 0.9'   DC 3   (40.0-cm reflector 144x) I could not see it at the highlight due to the bad weather or low location. But I could see it again before it went away. Unexpectedly, the comet was still visible visually. My estimation is 12.6 mag, but I felt it much fainter. The magnitude becomes 13.7 mag if I use the GSC as reference. 73P-C/Schwassmann-Wachmann 3 13.9 mag   Dia. 1.2'   DC 3-4   (40.0-cm reflector 144x) Unexpectedly, the comet was still visible visually. But it is near the limit now. 117P/Helin-Roman-Alu 1 13.2 mag   Dia. 1.3'   DC 4   (40.0-cm reflector 144x) Not so fine as before due to the sky condition. But the comet was definitely visible visually. It seems small but well condensed. 177P/Barnard 2 10.5 mag   Dia. 3.0'   DC 2   (40.0-cm reflector 75x) It became fainter than before. It is not clear with a lower magnification. The central condensation was visible, but the surrounding coma was very large and faint. So I felt it very diffuse.

2006 Aug. 22 (7 comets) I observed 7 comets visually on Aug. 22 in Kita-karuizawa, Gunma, Japan. Weather had been bad since May in Japan, and I could finally observe comets after a long blank of three months and a half. I could have fine weather only one day during my stay of four days. But I could have an excellent clear sky for 45 minutes around midnight, and I could see some faint comets visually for the first time! P/2006 HR30 ( Siding Spring ) 15.5 mag   DC 9   (40.0-cm reflector 257x) Clearly visible with an excellent clear sky. It looks stellar, completely similar to background faint stars. 4P/Faye 11.7 mag   Dia. 1.6'   DC 7-8   (40.0-cm reflector 144x) Already very bright! Very strongly condensed and easy to see. I could notice the tail. 29P/Schwassmann-Wachmann 1 13.2 mag   Dia. 1.1'   DC 1   (40.0-cm reflector 144x) Very diffuse weak object with no condensation. 73P-B/Schwassmann-Wachmann 3 fainter than 12.6 mag   Dia. 0.8'   (40.0-cm reflector 144x) I tried to observe it after a blank of three months. But it is already too faint to see. The limiting magnitude is brighter than the brightness of the component C itself, possibly due to the morning glow. 73P-C/Schwassmann-Wachmann 3 13.0 mag   Dia. 1.0'   DC 4-5   (40.0-cm reflector 144x) I could observe it after a blank of three months since the remarkable approach to the earth. Now it is very small, but still visible visually. Moderately condensed. 117P/Helin-Roman-Alu 1 13.7 mag   Dia. 0.9'   DC 5   (40.0-cm reflector 144x) Unexpectedly, it was clearly visible with an excellent clear sky. It is brighter than expected! Moderately condensed. 177P/Barnard 2 9.1 mag   Dia. 8.5'   DC 2   (40.0-cm reflector 36x) Remarkable comet in this summer, Barnard 2, returning since 1889. The weather had been bad, but I could finally see it. Very diffuse nebulous object only with a hint of central condensation. Large, but not extremely large. It recalled me 55P/Tempel-Tuttle.

2006 Apr. 29-May 4 (13 comets) I observed 13 comets visually between Apr. 30 and May 4 in Kita-karuizawa, Gunma, Japan. I also report my observation of 73P-C on Apr. 29 in Toride, Ibaraki, Japan. I have been staying in mountain location in Kita-karuizawa for a week to observe Comet 73P/Schwassmann-Wachmann 3. Fortunately, I could have fine weather during my stay. It was fantastic to see the two naked eye fragments of 73P, C and B. The component C was magnificent. The component B had been brightening rapidly during this period. However, other fragments were much fainter than expected. Actually, I could not see the "train" of many fragments visually. I was very busy guiding my telescope to many components, but only disappointed because they were very faint. But, the two components C and B were fantastic anyway, and there were some more many visual comets in the sky, so I could enjoy. In fact, I printed charts using somewhat old orbital elements. So the positions of the components N and R were very different. Especially, I heard the component R became 12-13 mag in early May, but I could not observe. Many observers reported it around 13 mag, however, I could see only a faint 15.0 mag star at the position. I wonder why, but it was due to the chart problem. Apr. 29: It was cloudy until midnight. But at 3 a.m., clouds were going away and part of the sky was fine. While I was preparing my monocular, whole sky became fine in a short time. I could only observe 73P-C in my home. Apr. 30: Hard raining in the evening. Still raining at 10 p.m. However, after a short sleep, the sky became completely fine at midnight. The fine weather continued after that. However, at 3:30 a.m., rain started falling down suddenly despite of the fine sky without clouds. I was observing 73P around zenith at that time, so I had to stow away my telescope in a hurry. Clouds came within 10 minutes, then it became completely rainy around 3:50 a.m. I have never experienced such a situation before, rain falling down while observing comets despite of the fine sky without clouds. May 1: It became fine in the evening, but hazy in the low sky. I saw thunder light in the north frequently. Then clouds came and it became rainy around 10 p.m. May 2: It was rainy in the morning, cloudy afternoon. However, the sky became fine rapidly after the sunset, and I could have an excellent clear sky with no clouds or haze at all at 7:30 p.m. Especially, the sky was excellent after moon set, when I enjoyed the complex pattern and Messier objects in the Milky Way with naked eyes. Stars were visible just after rising or before set. The sky was completely dark until morning, except for the eastern low sky which influenced by the city light of Tokyo. May 3: Fine weather continued from the previous day. But the sky was slightly hazy in the evening and influenced by the moon light. After midnight, after the moon set, the sky was very clear. However, it became hazy suddenly around 3 a.m., then whole sky was covered with thin clouds soon. May 4: Fine weather still continued. But the sky became more hazy. It was strongly influenced by the moon light in the evening. Thin clouds existed in the low sky. But the seeing was excellent. I enjoyed Saturn with high magnification, which looked similar to the photo by Hubble Space Telescope. After midnight, after the moon set, the sky was very clear. Thin clouds in the low sky disappeared at dawn. C/2003 WT42 ( LINEAR ) May 1   12.8 mag   Dia. 1.0'   DC 6   (40.0-cm reflector 144x) May 2   13.1 mag   Dia. 1.1'   DC 5-6   (40.0-cm reflector 144x) May 3   13.3 mag   Dia. 0.9'   DC 6   (40.0-cm reflector 144x) May 4   12.8 mag   Dia. 0.8'   DC 5   (40.0-cm reflector 257x) Round ball, but not so tiny. It looks well in the clear sky. But the central condensation became somewhat weaker. On the other hand, it became somewhat larger. On May 1, it felt it so faint, but my estimation became similar to the other days. I observe it after moon set on May 3. C/2004 B1 ( LINEAR ) Apr. 30   12.0 mag   Dia. 2.5'   DC 2-3   (40.0-cm reflector 144x) May 2   12.2 mag   Dia. 1.0'   DC 4   (40.0-cm reflector 144x) May 3   12.5 mag   Dia. 1.2'   DC 3-4   (40.0-cm reflector 144x) May 4   12.6 mag   Dia. 1.5'   DC 3-4   (40.0-cm reflector 144x) On Apr. 30, it looked very large and diffuse. But using a 0.40-m telescope, the central core was clearly visible. It was impressive to see the comet floating among many stars in the Milky Way. It was diffuse anyway, so I see some estimated it much fainter or failed to see it without clear sky. After May 2, I estimated smaller than Apr. 30, probably due to the nearby stars. On the other hand, it looked moderately condensed, probably because I saw only the central core. C/2005 E2 ( McNaught ) May 2   9.7 mag   Dia. 1.6'   DC 3   (40.0-cm reflector 144x) May 3   9.8 mag   Dia. 1.4'   DC 3-4   (40.0-cm reflector 144x) Extremely low in the evening, but I could see it just over the ridgeline under the clear sky. Unexpectedly, it is not too faint still now. Diffuse but not so tiny. C/2006 A1 ( Pojmanski ) Apr. 30   11.1 mag   Dia. 1.4'   DC 1   (40.0-cm reflector 144x) May 2   11.7 mag   Dia. 1.9'   DC 3   (40.0-cm reflector 144x) May 3   12.3 mag   Dia. 1.5'   DC 3   (40.0-cm reflector 144x) May 4   11.9 mag   Dia. 1.6'   DC 3   (40.0-cm reflector 144x) Very diffuse, but the central core is clearly visible. It was impressive to see the comet floating among many stars in the Milky Way, similar to C/2004 B1. The central core looks moderately condensed and the comet is an enjoyable target still now using a 0.40-m telescope. On May 2, I felt it very bright and large under the clear sky. On May 4, it was near by a 12 mag star but the comet was clearly visible. Magnitude of my estimations had been fading day by day. But I did not feel it was fading rapidly at that time. 4P/Faye May 2   fainter than 13.2 mag   Dia. 0.5'   (40.0-cm reflector 257x) May 4   fainter than 12.3 mag   Dia. 0.5'   (40.0-cm reflector 257x) Very low in the morning, but I could see very faint stars on May 2 under the clear sky. Maybe something was visible at the position on May 2. But I could not see 14 mag stars, so it was not a comet, I guess. It was also fine on May 4, however, the limiting magnitude says it was much more hazy. 41P/Tuttle-Giacobini-Kresak May 1   13.6 mag   Dia. 0.6'   DC 3   (40.0-cm reflector 257x) May 2   13.1 mag   Dia. 1.0'   DC 3   (40.0-cm reflector 144x) May 3   fainter than 11.5 mag   Dia. 0.6'   (40.0-cm reflector 144x) May 4   12.4 mag   Dia. 0.7'   DC 3   (40.0-cm reflector 257x) Very near by Moon. On May 1, the sky was very hazy. On May 3, it was only 4 degree from half moon, and very near by a 9 mag star. So the condition was extremely bad, but I confirmed if an outburst occurred or not. As a result, no major outburst occurred during my stay for a week. Magnitude of my estimations had been brightening rapidly day by day. But I did not feel it was brightening rapidly at that time, because Moon had been brightening day by day at the same time. 71P/Clark Apr. 30   12.2 mag   Dia. 0.7'   DC 4   (40.0-cm reflector 144x) May 2   12.7 mag   Dia. 0.7'   DC 3   (40.0-cm reflector 144x) May 3   12.6 mag   Dia. 0.8'   DC 4   (40.0-cm reflector 144x) May 4   12.4 mag   Dia. 1.3'   DC 4   (40.0-cm reflector 144x) Unexpectedly bright already. Somewhat low and not easy to see. It looked small. But only on May 4, it looked unexpectedly large. 73P-B/Schwassmann-Wachmann 3 Apr. 30   7.1 mag   Dia. 13'   DC 3-4   Tail 0.5 deg (p.a. 230 deg)   (10x70 monocular) Apr. 30   7.1 mag   Dia. 14'   DC 3   (10x24 binoculars) May 2   6.8 mag   Dia. 19'   DC 6   Tail 0.6 deg (p.a. 250 deg)   (10x70 monocular) May 2   7.1 mag   Dia. 20'   DC 4-5   (10x24 binoculars) May 3   6.4 mag   Dia. 26'   DC 7   Tail 0.7 deg (p.a. 230 deg)   (10x70 monocular) May 3   6.0 mag   Dia. 33'   DC 3-4   (10x24 binoculars) May 4   6.2 mag   Dia. 29'   DC 7   Tail 0.8 deg (p.a. 245 deg)   (10x70 monocular) May 4   6.1 mag   Dia. 26'   DC 6   (10x24 binoculars) Another outburst occurred during my stay. It had been brightening and the central condensation had been getting stronger day by day. On Apr. 30, it was still diffuse and the central condensation was weak. The coma looked elongated, as if it were in disruption. The nucleus was not so sharp even using a 0.40-m telescope. On the contrary, it looked somewhat elongated. But on May 2, it became very large and moderately condensed. Using a 0.40-m telescope, a bright stellar nucleus was evidently visible, which was not visible two days ago. Even using smaller monocular or binoculars, the central condensation had been getting stronger day by day. Finally, it became looking similar to the component C using a 0.40-m telescope. But using smaller monocular or binoculars, it looked very large, diffuse and nebulous, completely different from the component C. Especially, it became extremely large on May 3 and 4. Very natural as a comet approaching towards Earth. On May 3 and 4, it was fantastic to see the rendezvous with M13. The comet was fainter, but much larger than M13. So the rendezvous was really an excellent view. I could see M13 clearly with naked eyes, but the comet was not clearly visible with naked eyes. 73P-C/Schwassmann-Wachmann 3 Apr. 29   6.3 mag   Dia. 12'   DC 6   (10x70 monocular) Apr. 30   6.4 mag   Dia. 12'   DC 7   Tail 0.8 deg (p.a. 235 deg)   (10x70 monocular) Apr. 30   6.2 mag   Dia. 12'   DC 7   Tail 0.4 deg (p.a. 235 deg)   (10x24 binoculars) May 2   6.4 mag   Dia. 13'   DC 7   Tail 2.5 deg (p.a. 250 deg)   (10x70 monocular) May 2   6.4 mag   Dia. 14'   DC 6-7   Tail 1.2 deg (p.a. 250 deg)   (10x24 binoculars) May 3   6.0 mag   Dia. 16'   DC 7   Tail 1.2 deg (p.a. 240 deg)   (10x70 monocular) May 3   5.9 mag   Dia. 14'   DC 7   Tail 0.6 deg (p.a. 240 deg)   (10x24 binoculars) May 4   6.2 mag   Dia. 12'   DC 7-8   Tail 1.4 deg (p.a. 240 deg)   (10x70 monocular) May 4   6.1 mag   Dia. 18'   DC 7   Tail 0.7 deg (p.a. 240 deg)   (10x24 binoculars) I estimated it brighter, and the tail was longer than others reported, probably due to the clear sky. Especially, I could see extremely long tail on May 2. Now it is already very near by the earth. But the central condensation is still very strong. Magnificent and fantastic view with a broad, very long tail. The tail looks typical for a dust tail of a historical great comet. Therefore, I cannot imagine the comet was already very near by the earth. On the contrary, it looks as if I was watching a great comet far away from the earth. However, on May 4, the tail seemed spreading widely. It was not clearly visible with naked eyes. I was surprised that it was already very bright as 6 mag on Apr. 29. However, it did not brighten during my stay for a week. 73P-G/Schwassmann-Wachmann 3 Apr. 30   fainter than 13.6 mag   Dia. 0.9'   (40.0-cm reflector 144x) May 2   13.9 mag   Dia. 1.0'   DC 2   (40.0-cm reflector 144x) It was very bright two weeks ago, but it became too faint to see on Apr. 30. I have read an e-mail from Shigeki Murakami that the component G already faded, so I was not very surprised. If I had not got that information, I might have been in panic. They say it is very diffuse, so I tried to see it with lower magnification, but failed. On May 2, I could see a very faint diffuse object due to the excellent clear sky, but near limit. On May 3, thin clouds came while observing the component G. I felt something was visible. But actually, it was a ghost of two 14.7 mag stars. On May 4, I watched a wrong position. 73P-AP/Schwassmann-Wachmann 3 Apr. 30   fainter than 13.4 mag   Dia. 0.6'   (40.0-cm reflector 144x) May 2   fainter than 13.9 mag   Dia. 0.6'   (40.0-cm reflector 257x) May 3   fainter than 13.9 mag   Dia. 0.6'   (40.0-cm reflector 257x) May 4   fainter than 14.2 mag   Dia. 0.6'   (40.0-cm reflector 257x) On Apr. 30, I could see a 14.9 mag star, but could not see the comet beside of the star. On May 2, the component BC was bright under the clear sky, but the component AP was not visible. On May 3, I felt a small object was visible, but it was a 15.5 mag star recorded in the USNO-A2.0 catalog. 73P-AS/Schwassmann-Wachmann 3 Apr. 30   14.2 mag   Dia. 0.8'   DC 3   (40.0-cm reflector 144x) May 2   13.8 mag   Dia. 0.6'   DC 2   (40.0-cm reflector 257x) May 3   fainter than 14.4 mag   Dia. 0.5'   (40.0-cm reflector 257x) Very tiny object was visible at the position. Similar to a faint star, and near limit. But I think I could see the component AS on Apr. 30 and May 2. I cannot observe it for a long time enough on Apr. 30 because rain started falling down suddenly while observing the component AS. However, it became invisible on May 3. The sky was very clear and I could see many faint stars not printed in my chart based on GSC. I recorded them, but they are 15-16 mag stars recorded in the USNO-A2.0 catalog. The comet must have been among those stars, but I could not find it. On May 4, I watched a wrong position. 73P-BC/Schwassmann-Wachmann 3 May 2   13.2 mag   Dia. 0.7'   DC 3-4   (40.0-cm reflector 257x) May 3   fainter than 13.9 mag   Dia. 0.7'   (40.0-cm reflector 257x) Although I could not see WWW during my stay for a week, Ken-ichi Kadota told me the information of the component BC, and I could see it. On May 2, it was very bright and large due to the clear sky. The fast motion among stars was evidently visible. However, on the next day, May 3, it became invisible. Maybe the component faded out rapidly. On Apr. 30, I did not know about the component BC. I did not find it while observing the component AP. The component BC must have been near by a cluster of three 13.5 mag stars. On May 4, I felt something faint, large and diffuse, but maybe condensed object at the position. It was a complicated ghost of a 15.5 mag star recorded in the USNO-A2.0 catalog and the component BC. I think the diffuse component BC was also visible, however, I could not estimate the brightness, diameter or other data of the comet itself.

2006 Apr. 17 (5 comets) I observed 5 comets visually on Apr. 17 in Mt. Hanadate, Ibaraki, Japan. I observed comets beside the cherry blossom trees in full bloom in the park. However, the sky was very hazy and the condition was very bad. Stars are hard to see except for the zenith part. So all comets were easier to see with higher magnification. The seeing was not very bad. I could enjoy Jupiter somewhat low in the morning. C/2003 WT42 ( LINEAR ) 13.0 mag   Dia. 0.6'   DC 5   (40.0-cm reflector 257x) The sky was very bad, however, the comet was visible at zenith. C/2006 A1 ( Pojmanski ) 9.1 mag   Dia. 1.9'   DC 2   (40.0-cm reflector 144x) The comet located somewhat lower and the sky was very hazy with strong moon light. So the condition was very bad. It seems diffuse and large. 73P-B/Schwassmann-Wachmann 3 9.6 mag   Dia. 3.0'   DC 3-4   (40.0-cm reflector 75x) Easy object but diffuse. The central condensation is typical, or somewhat weaker, so I could not find any sign of disruption. I could not see it at the outburst in early April. Now I could no longer find any sign of outburst. Surely fainter than the component C. 73P-C/Schwassmann-Wachmann 3 9.1 mag   Dia. 4.0'   DC s7   (40.0-cm reflector 75x) The outer coma seems very large. It seems to have become much larger than before. The central condensation is strong as before in spite of the hazy sky condition. 73P-G/Schwassmann-Wachmann 3 11.7 mag   Dia. 0.8'   DC 5   (40.0-cm reflector 257x) It became much brighter than before and I could see it in spite of the hazy sky condition. Moderately condensed. It was easier to see after the moon rise when it located around zenith.

2006 Mar. 31 (8 comets) I observed 8 comets visually on Mar. 31 in Mt. Hanadate, Ibaraki, Japan. It was fine from midnight to morning, but the sky was a bit hazy and not an excellent clear sky. Due to the poor seeing, the higher magnification (257x) did not help to see faint stars. Unfortunately, two bright comets were overlapping on stars and impossible to observe in good condition. I also tried to observe P/2005 XA54, P/2004 VR8. But they were not visible, and not worth being reported due to the bright limiting magnitude. C/2003 WT42 ( LINEAR ) about 13.1 mag   Dia. 0.7'   DC 6   (40.0-cm reflector 144x) It was just overlapping on a 13.5 mag star at midnight. I observed it when the comet moved apart from the star, so it became lower. The comet was still very close to the star, so not easy to see. C/2004 B1 ( LINEAR ) fainter than 10.7 mag   Dia. 0.8'   (40.0-cm reflector 144x) Unfortunately, the ephemeris says the comet overlaps on a 11.8 mag star when the morning glow starts. So I tried to observe it earlier, when the comet was still very low. But due to the poor condition, I could see only bright stars. Anyway, the comet was much fainter than 9 mag, originally expected. Katsumi Yoshimoto reported it as 12.6 mag by CCD, so it should be around 11.5-12 mag visually. C/2004 D1 ( NEAT ) fainter than 13.9 mag   Dia. 0.5'   (40.0-cm reflector 144x) CCD observers reported it 15.5 mag. But I thought it could be much brighter visually, like C/2003 WT42. So I tried to observe it, but the comet was too faint to see. C/2006 A1 ( Pojmanski ) 7.6 mag   Dia. 5.5'   DC 6-7   (10x70 monocular) 7.9 mag   Dia. 3.3'   DC 6-7   (40.0-cm reflector 36x) It looked like a typical featureless bright comet, a simple round ball. Not so interesting as 73P. Moderately condensed and easy to see. Still visible through a 7-cm monocular. The view was impressive, the comet looked over many faint stars in the Milky Way. 71P/Clark fainter than 13.0 mag   Dia. 0.7'   (40.0-cm reflector 144x) I think it is about to be visible visually. But I could not see due to the poor sky condition. This time the position was easy to find, and I could see the ASAS data. However, the GSC and USNO-A2.0 data seem incorrect around this field, so people may have difficulty to observe it. 73P-B/Schwassmann-Wachmann 3 11.9 mag   Dia. 1.4'   DC 6   (40.0-cm reflector 144x) Already very bright. Easy to see through a 40-cm reflector. Moderately condensed and easy to see. The central condensation of the component B is not so sharp as the component C. No stellar nucleus was visible. 73P-C/Schwassmann-Wachmann 3 9.6 mag   Dia. 3.0'   DC S7   Tail 6' (p.a. 255 deg)   (40.0-cm reflector 36x) It brightened drastically within last three weeks. Now it is easy to find when I moved my telescope roughly to the position. Excellent view with a broad tail. The central condensation is very strong as before. The stellar nucleus is clearly visible. 73P-G/Schwassmann-Wachmann 3 fainter than 13.7 mag   Dia. 0.9'   (40.0-cm reflector 144x) Not visible still now.

2006 Mar. 4-5 (5 comets) I observed 5 comets visually on Mar. 4 and 5 in Mt. Hanadate, Ibaraki, Japan. On Saturday, many people came to see Comet Pojmanski! They said it had been find until midnight. However, when I arrived at 2 a.m., it was completely cloudy. But surprisingly, just before the morning glow began, the clouds started going away, then the weather suddenly became fine. So we could have a fine sky only for a quarter hour and succeeded to see Comet Pojmanski! But the sky was covered with thin clouds, so the condition was poor. On Sunday, the weather was fine, but the sky was hazy. The condition to see comets was much worse than Feb. 27. C/2003 WT42 ( LINEAR ) Mar. 5   13.1 mag   Dia. 0.9'   DC 6   (40.0-cm reflector 144x) It looked more unfavorable than Feb. 27 due to the hazy sky and the half moon. But the comet was clearly visible, small and strongly condnesed as before. P/2005 XA54 ( LONEOS-Hill ) Mar. 5   fainter than 14.1 mag   Dia. 0.5'   (40.0-cm reflector 257x) Not visible. I could see faint stars down to around 14.5 mag. But the sky was hazy and hard to see a faint comet. However, the limiting magnitude was fainter than my estimation of this comet on Feb. 27. C/2006 A1 ( Pojmanski ) Mar. 4   5.2 mag   DC 8-9   (10x70 monocular) Mar. 4   5.2 mag   Dia. 2.7'   DC 7   (40.0-cm reflector 36x) Through thin clouds, but the comet was very bright! Finally I could see it. Already high enough. Very small and strongly condensed. Almost stellar with a 10x70 monocular, impossible to estimate the diameter. But it looked slightly cometary comparing to other background stars. Also very small through a 40-cm reflector. No tail was confirmed due to the poor condition. But the coma was elongated, fan shaped. Maybe the tail extends towards two directions as pointed out by Shigeki Murakami. 73P-B/Schwassmann-Wachmann 3 Mar. 5   13.8 mag   Dia. 0.5'   DC 5   (40.0-cm reflector 257x) Near limit due to the poor condition. Hard to see. Maybe it brightened somewhat during last one week. 73P-C/Schwassmann-Wachmann 3 Mar. 4   12.4 mag   Dia. 1.1'   DC 6   (40.0-cm reflector 144x) Mar. 5   12.1 mag   Dia. 1.0'   DC 7   (40.0-cm reflector 144x) The comet was bright and clearly visible even through thin clouds on Saturday. On Sunday, it looked strongly condensed and the false nucleus was visible.

2006 Feb. 27 (7 comets) I observed 7 comets visually on Feb. 27 in Mt. Hanadate, Ibaraki, Japan. It was almost cloudy but sometimes fine in the daytime. In the evening, the clouds became thinner, but the sky was still covered with thin clouds and hazy. So no faint stars were visible. However, the clouds went away and I could have excellent clear sky for several hours around midnight. But unfortunately, the clouds came again around 3 a.m., then the sky was completely covered with clouds before dawn. I could not see Venus, and of course I could not observe C/2006 A1. C/2003 WT42 ( LINEAR ) 13.4 mag   Dia. 0.6'   DC 6-7   (40.0-cm reflector 144x) Very bright. Enjoyable target for a 40-cm telescope. It is easy to see due to the clear sky and high location. Small and strongly condensed as before. P/2004 VR8 ( LONEOS ) 14.0 mag   Dia. 0.7'   DC 4   (40.0-cm reflector 144x) Faint small object. Maybe it became somewhat brighter than January. C/2005 E2 ( McNaught ) about 9.9 mag   Dia. 1.5'   DC 3   (40.0-cm reflector 144x) I tried to observe it still in the evening glow. The comet was blocked by the clouds before the glow ended. So my observation is in the evening glow. Because observing through thin clouds, it was not easy to see, and my estimation is inaccurate. But it was clear that a diffuse wide object existed. P/2005 XA54 ( LONEOS-Hill ) 14.0 mag   Dia. smaller than 0.5'   DC 7-8   (40.0-cm reflector 144x) Unexpectedly bright and clearly visible. Very tiny, so it looks like a faint star at a glance. However, using a higher magnification, background stars looks exactly point-like in focus, but the comet did not look so. Therefore it seems to be cometary, not stellar, although the condensation is strong. I observed it twice with 3.5 hour interval and confirmed the motion. 29P/Schwassmann-Wachmann 1 fainter than 12.1 mag   Dia. 0.8'   (40.0-cm reflector 144x) Because of the thin clouds, no faint stars were visible. Maybe something was visible at the position. Maybe it was 29P in outburst. But I could not confirm it in the hazy sky. Anyway, the comet must be fainter than 12.1 mag. 73P-B/Schwassmann-Wachmann 3 14.4 mag   Dia. 0.5'   DC 4   (40.0-cm reflector 144x) Extremely faint, nearly limit, hard to see. 73P-C/Schwassmann-Wachmann 3 12.3 mag   Dia. 1.1'   DC 7   (40.0-cm reflector 144x) Finally I could see it. Very bright! Already easy to see. In the excellent clear sky, the central condensation was very sharp. The broad short tail extended from the false nucleus, which reminded me the recent CCD images. Excellent and fantastic view.

2006 Jan. 8 (8 comets) I observed 8 comets visually on Jan. 8 in Mt. Hanadate, Ibaraki, Japan. I could have an excellent clear sky all night, although a bright half moon interfered in the evening. The air seemed very dry. Probably that is why the sky has been so clear. I could have an excellent view of surrounding mountains far away at dusk and after sunrise. I also tried to observe C/2005 N1. But the GSC data is illegal just around the comet position. So I could not determine the exact position of the comet and failed to observe it. (60558) 2000 EC98 14.4 mag   Dia. 0.5'   DC 3   (40.0-cm reflector 257x) This object has been revealed to be a comet just before I left home for observation. It was reported as 17.5 mag in IAUC 8656, but I received a report by Ken-ichi Kadota that this comet is much brighter actually, 14.8 mag on Jan. 7.85 (UT). So I hurriedly added it to my target list. This comet is farther than 13 A.U., but surprisingly, it is visible visually! Maybe it is the farthest comet observed visually, isn't it? Before the observation, I have imagined that it would be sharply and strongly condensed like 29P just after an outburst. However, on the contrary, it is very diffuse actually. Round diffuse object like a planetary nebula, similar to Owl Nebula. Kadota reported that the condensation became somewhat weaker on Jan. 8 than Jan. 7. Maybe the outburst has been already cooling down? C/2003 K4 ( LINEAR ) fainter than 13.0 mag   Dia. 0.8'   (40.0-cm reflector 144x) Very near by the half moon, so I could not see the comet. A 14.1-mag star was visible. C/2003 WT42 ( LINEAR ) 13.7 mag   Dia. 0.5'   DC 6   (40.0-cm reflector 257x) Not changed at all since October, it did not brightened. The condensation is strong as before, and easier to see with higher magnification. With lower magnification, it looks more diffuse as DC=3 or so. C/2004 Q2 ( Machholz ) fainter than 13.9 mag   Dia. 0.4'   (40.0-cm reflector 257x) Appearing in the morning sky, and I tried to see it. The limiting magnitude was not deep due to the low altitude, and I could not see the comet. P/2004 VR8 ( LONEOS ) 14.8 mag   Dia. 0.4'   DC 3-4   (40.0-cm reflector 257x) Nearly limit, but a very faint small object was visible. The comparison stars are from USNO-A2.0, so the real magnitude may be somewhat brighter. C/2005 E2 ( McNaught ) 10.1 mag   Dia. 1.8'   DC 3-4   (40.0-cm reflector 144x) Very diffuse. The sharp condensation observed last summer and early autumn has disappeared at all. Very different from my last observation three months ago. I was surprised it was faint and not easy to see, although it may be due to the moon light and low altitude. But the comet was clearly visible anyway with 40-cm reflector. 29P/Schwassmann-Wachmann 1 fainter than 13.1 mag   Dia. 0.7'   (40.0-cm reflector 144x) Extremely near by the half moon, so it was very difficult to see a diffuse object. Anyway, the comet was too faint to see. 73P/Schwassmann-Wachmann 3 fainter than 14.7 mag   Dia. 0.4'   (40.0-cm reflector 257x) Juan Jose Gonzalez reported it was visible visually as 15.2 mag. But I could not see the comet, although the limiting magnitude was very deep.

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