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2006

Tue Dec 26

As forecast predicted there are no cloud this predawn but transparency was pretty poor as opposed to yesterday. I set up the scope and started sweeping the sky at 4 a.m., however, it became extremely hazy in a short time. At 4:10 a.m. Beta Corvi was deteriorated to naked eye limited. I waited for 10 minutes but the sky became worse and I decided to stop today's session.


Mon Dec 25

Wonderful sky! Though
today last year snow depth was much deeper than my stature, today there was no snow at the summer observing site. Under excellent transparency I began to comet hunt at Eta Corvi. The movement of the telescope was very smooth.
I conducted vertical method as usual. I swung the scope downward from an altitude of some 40 degrees and when it reached the horizon I shift the field about 0.3 degrees northward (rotate the scope counterclockwise)
; this value must be varied depending on azimuth. Then, I quickly raised up the telescope until 40 degrees in altitude without looking through the eyepiece and repeated sweeping downward; due to a sidereal motion and the northward shift the field is overlapped by one third as a result.

Unexpectedly, I caught a lot of galaxies in the former half of today's comet hunting session. The first galaxy I detected was M104. From here to Spica, Alpha Virginis, I spotted 26 galaxies excluding M104. Many of them were 12th magnitude or brighter and some were 13th. I wondered if here are so many galaxies in this region. Dark and clear sky is treasure for a comet hunter. At first I could enjoy identifying them, however, it came to check a few galaxies in one field, I began to feed up with catching galaxies.

The latter half of the session, the search area of the north of Spica, I could observe only four galaxies: NGC5426, 5427, 5493 and 5634. Light pollution and zodiacal light must reduce the number of observable galaxies. I stopped comet searching at 6:00 a.m.; the biginning of the towilight was late. It was winter solstice on December 22, and I could afford to have 2 hours and 20 minutes comet hunting hours. This is one of the longest comet hunting hours in one session.


Wed Dec 13

Again, I woke up at ten past 2 a.m., though I set  the alarm clock at 2: 40 a.m. I also got up this time yesterday before the alarm rang but in vain: on Monday evening the forecast said it would be clear on Tuesday predawn. Anyway, this is the first comet hinting session this month!

This predawn it turned out that  the sky was clear before I looked at the sky through  the window, since the moonlight shined into the room from the opening between the curtains. I drove to the observing site but usual site was inaccessible due to snow accumulation. I headed for the winter site, it is a rather wide parking space beside the road where snow is cleared away.

Everything was winter version except my mind. It was cold and I put on a pair of gloves. Then, I began to assemble my 46 cm telescope. Ouch! the rocker box of my Dobsonian slipped out from my hands because I put on the gloves. Unfortunately, it hit my knee and I had to stood a severe pain for a minute under the cold moonlight. I had been always glove less when I carried the rocker box in wintertime. However, I forgot about it since this is the first winter version session. My knee slightly bled internally and the bottom edge of the rocker box was damaged.

OK, the pivot was safe and I finished assembling the scope. After that a cooling fan for a primary mirror and a dew remover stopped due to low battery under the low temperature. This often happens in winter. I changed it and at last started comet hunting.

The contrast in the field was low because of moonlight but it was improved as the telescope getting away from the moon. At 5:00 a.m., a quarter before the beginning of the twilight, thin cloud spread all over the sky and a halo appeared around the moon. I finished the session and enjoyed Sturan and Moon using BinoVue. Though I observed them through cloud, they were still impressive! Contrary to the previous comet hunting session, the only comet like object I caught was M53.


Sun Nov 26

The forecast of last Sunday that predicted unfavorable weather did not come true and there were three fine days since then including today.

I got up at 2:20 am,10 minutes before the alarm clock rang, and drove to the usual observing site. Wind was very strong at the site and I moved to in the lee of the cliff where it took only two minutes drive from my usual observing site. I could recognize counterglow just below M45 in the same way as yesterday.

I began to comet search at 3:25 am but scintillation was very bad; it was difficult even to distinguish a star whose image was swelled by the strong wind from a small size galaxy. I could not concentrate on the hunting and was irritated. However, there was another reason that made me nervous.

Last night I wondered if I should identify all the galaxies I would catch in the coming predawn. At that time I decided to search the Coma Berenices and Virgo region where there are so many galaxies. In Saturday predawn I detected 41 galaxies mainly in Virgo and I have got bored. What is the right way of comet hunting in this region?

Tsutomu Seki's book reads that he recommends to search this region but it is almost impossible to identify all the galaxies we catch. In stead, we have to pay attention to "abnormal image" he said. Galaxies in the region are darker than 9th magnitude and if a brighter object is there it must be a new comet. Another point is that many comets have diffused image that is deferent from that of galaxies. All we can do is to check these unusual images, he said.

This is the first time I dared to sweep this region under excellent transparency using 46 cm comet seeker and I did not know how many galaxies I would catch; that must be huge number.

As a result when I began to comet hunt I made up my mind to identify all the galaxies. Because I am a comet hunter not a deep sky observer. What if there is a new comet of 13th magnitude? On top of this, I have to consider that the time has changed; when Seki's book had published the digital setting circles were not available nor excellent star charts. Now that these modern tools are in my hand, it is much easier to identify many galaxies in a short time.


Near M86
I could detected 6 galaxies in this image. 1 degree square.
The Digitized Sky Survey copyright © 1994

Even so, actually it is a hard work to identify them all. Identifying a single galaxy is easy. I can do it with the digital setting circles using "search mode". However, I need to utilize both the electric gadget and the Uranometria 2000 when it comes to I catches several galaxies in the same field. I know  Right Ascension and Right  Declination but quite a few of galaxies, much darker than I can observe, are printed at the position! I have to rotate the chart and compare the field and the chart.

As result, I could identify 68 galaxies, some of which were 13th magnitude, and 3 globular clusters (M53, NGC5053 and M5). Scintillation became much better before I knew it and I found myself enjoying various forms of galaxies.

After completed the hard work, I felt something satisfactory.
Oh, Mercury rose above the horizon. Wonderful dawn!


Sun Nov 19

This predawn temperature was 1 degree Celsius and frost was formed for the first time this fall. My motion was slower than that of a week ago and it took a bit longer to assemble my 46 cm telescope because of  thick winter clothes and arctic boots.

In spite of rather poor transparency and partial thin cloud, I caught half a dozen of  galaxies in Hydra, most of them were 11 th magnitude. After 4:30am the amount of cloud increased and covered most part of eastern sky but I continued comet hunting through thin cloud or among cloud gaps.

When I was about to finish this predawn's comet hunting session at around 5:20 am, I observed very bright satellite, zero magnitude, fly near Denebola, Beta Leonis; that turned out to be The International Space Station (ISS) after I got home. In the lower south-east, waning crescent moon with earthlight was impressive.

Winter is just around the corner; according to the outlook for the coming week,
nasty weather will last.




A curve with a red arrow is the course of ISS, around 5:20 am, Nov 19, 2006 at my observing site.
Chart: The Heavens Above
http://www.heavens-above.com/


Sat Nov 4

There were so many fine days last month that I could comet hunt 14 times. This is a new record on a monthly basis.

This predawn the gibbous moon was in the sky till 4:15 am;  half hour before the beginning of the twilight. Though
I could comet hunt  one hour, the clarity of the sky was less than average.

I dared to sweep Coma Berenices and Virogo region where there are many galaxies.
The list shown below includes all the Messier Objects within my search area, some of which could not be detected, and NGC Objects that I could caught this predawn. The order of the list is the same with the time course of what
I caught or could have caught the objects.

Altitudes of the objects were less than 25 degrees except M64 that was higher. I noticed NGC4478 and 4340 when I detected M87 and NGC4350, respectively.
Surface brightness (SB) of 13.0  or magnitude of 10.0 looks threshold to be detect the comet like objects this predawn but this is not always true. A state of  mind seems one of the major factors to detect faint objects.

Magnitude and SB were derived from "The Night Sky Observer's Guide", G.R. Kepple & G. W. Sanner, Wilmann-Bell, Inc., 1999.

Telescope: 46 cm 68x
Detected?   M or NGC  Mag.      SB
           Y         60            8.8       12.8    Galaxy
           N         59            9.6       12.5    Galaxy, altitude was about 15 degrees.
           Y         89            9.8       12.3    Galaxy
           Y         90            9.5       13.6    Galaxy
           N         58            9.7       13.0    Galaxy, altitude was about 15 degrees.
           Y         87            8.6       12.7    Galaxy
           Y      4478          11.4      12.2    Galaxy; one of the companions of M87
           Y      4473          10.2      12.4    Galaxy
           Y      4477          10.4      13.1
    Galaxy
           Y      4340          11.2      13.7
    Galaxy; companion of  4350  
           Y      4350          11.0      11.8
    Galaxy
           Y      4293          10.4      13.2    Galaxy
           N         91           10.2      13.3    Galaxy
           Y         88             9.6      12.6    Galaxy
           N       100             9.3      13.0    Galaxy
           Y         85             9.1     
13.0    Galaxy
           Y      4394          11.0      11.8    Galaxy
           Y      4651          10.8      12.9    Galaxy
           Y         64             8.5      12.4    Galaxy
           Y         53             7.5         -      Globular Cluster


Thu Oct 19

Clear sky! Thanks to a lot of fine days of this month, this is my 9th comet huntign sesion in October.

Again, I swept Leo as I did October 4 and 17. Though I could not detect C/2006 T1 Levy this predawn either which had a magnitude of 10.3 according to the report by S. Utsunomiya, I caught 18 galaxies during this comet hunting session in the Leo region. However, I could not catch some dark ones, for example NGC3628 near M65 and M66; one reason was that the moon was still bright and affected comet hunting at the moon age of 27 days and another was that transparency was moderate.

Anyway, it is interesting that I caught only three galaxies on Tuesday but eighteen today in the same area. Now, you can know how the moonlight affect the detectivity in comet hunting.


Tue Oct 17


Comfortable weather! I began to sweep the sky near the head of Leo as I did on October 4. The 25 days old moon was still bright but I dare to search near the moon. The telescope swept M44, M67 and the moon located in  the  head of  Leo. NGC2903 was very faint when I introduced it using the digital setting circles at 2:30 am, but it looked much brighter due to high altitude when I caught it during the comet hunting session: absorption of the light by air mass made a big difference.

After I searched almost all the "body" of Leo from the south to the north conducting vertically survey, I got back to the lower sky in the east: I swept Sextans and hind legs of Leo where I could not search one hour and half before since the area was under the horizon. 

Although I spent more than two hours for this comet hunting session, as a result all the comet like objects I caught were NGC2903, M105 and NGC3521. I could not caught C/2006 T1 Levy either, which was within the reginon I swept because of the moonlight.

Wed Oct 4

I have discovered a new comet this predawn!

However, the comet turned out to be C/2006 T1 Levy, which was announced IAUC only 3 hours and 43 minutes before my discovery.
How sever it is!

The ediscoveryf story is here.


Wed Sep 20-Thu Sep 21

After one hour drive I arrived at one of the best observing sites at 7:15pm. The collimation of my 46cm comet seeker had completed at 19:27pm and I started comet hunting session at 19:38pm. Only after 10 minutes cloud covered all the sky.

Luckily, cloud gap spread in a few minutes and I could continue comet hunting, though cloud still covered most part of the sky. Around 9pm, the sky became clear without cloud. However, I got tired and stopped comet hunting at 9:25pm.

Then, I observed 4P/Faye and 177P/Barnerd with Lumicon Comet filter. Contrast was much enhanced for 177P and it looked much brighter using the filter. On the contrary, 4P was slightly darker with the filter, that is, the filter gave an opposite effect for this comet. I have applied other two filters, IDAS LPS-P2 and IDAS LPS-V3 filters, for some comets. All the filters showed positive effect or at least no effect for all the comets, but this is the first time that the filters revealed the negative effect.

Under the Milky Way: The supreme time@2006 Sep 20

After some 4 hours sleep in my vehicle, I got up at 2am. Wonderful sky! I could observe M33 by my naked eyes with direct vision. I could even observe its shape. M31 was about to immerse into the Milky Way! I wondered if the Milky Way was so wide.

After enjoying some deep sky objects I began to comet seeking at 2:35am but unexpectedly, it was cloudy again in 20 minutes. After that I cloud comet hunt only additional 20 minutes. Even so, I did do my best; I searched southeast, where Kreutz Sungrazers would appear.

Sat Sep 2

Wonderful sky with high transparency urged me to drive to the highland observing site. After one hour drive I arrived at a pasture at an altitude of 850 m. The sky looked awful with so many stars! The Milky Way flows as the same way from the ancient times and people must have had a feeling of awe-inspiring like me. This must be the best condition this year. One hour drive was rewarded.

I began to enjoy star watching before comet hunting at 0:30am. Many stars resolved in the globular clusters M2 and M15, the supernova remnants NGC6992-6995 (Veil Nebula) and NGC6960 were impressive with complex structures using OIII and UHC filters, and at least three dark lanes were apparent in M31 with direct vision. NGC7293, the Helix nebula, could be detected by 5 cm finder.


M33
The Digitized Sky Survey copyright © 1994

However, the highlight was five spiral arms in M33 that could be observed with direct vision! I recognized some HII regions in the galaxy: NGC 604 is the brightest among them and could be seen easily. I tried to observe M33 with naked eyes, and I could see it with averted vision. The naked eye limiting magnitude was only 6.1, unexpectedly, in spite of my good first impression for the sky.

Some one dozen years ago, I could observe M33 by naked eyes with direct vision at my parentsf house where light pollution was much more serious than that of my residence at present. Light pollution became much more serious in this decade or so. How disappointing! Even so, I was impressed by the starry sky at the site. I have to cont my blessing because I could enjoy observing the deep sky objects and comet hunting around my town.

After enjoying the deep sky objects I comet hunted for 2 hours and half. I took some breaks during the comet searching session. One reason was that I could not concentrate on long hunting hours and another was unstable weather: cloud covered entire sky from time to time. At the time of twilight zodiacal light went up from the horizon, extended to Castor and Pollux and crossed the Milky Way.

Sun Aug 27

I did not intend to get up this predawn, but fortunately I did before 3a.m. due to a bike noise of a newspaper carrier. About 40% of the sky was covered with cloud; however, the sky condition was good enough to do comet hunting.

It has been cloudy through the night in spite of clear sky during daytime in the latter half of this month. In Friday predawn I went out and assembled 46 cm telescope under the excellent sky condition; clouds spread all the sky when I finished assembling the telescope until the beginning of the twilight. It was momentary fine weather. Yesterday, I woke up at 4a.m., and it was cloudy as the weather forecast predicted. Today, it was exceptional.

OK, went out and began!
However, it was less than one hour until the beginning of the twilight and it was time consuming to assemble 46 cm comet seeker; it takes some 30 minute to stand by. This time, I decided to use 20 cm telescope. To initialize the digital setting circles I trained the scope on Capella, Alpha Aur, and felt if it was actually Capella because it looked much darker in the field than usual. Soon I recognized that I used 20 cm instead of 46 cm and understood the reason.

NGC1907, open cluster near M38, looked like a comet with this instrument, but it is resolved using 46 cm that I routinely employ. 20 cm is comfortable to operate and is easy to assemble, but the light gathering power and the resolution are much less than those of 46 cm. I prefer to use the larger one if I can afford, since I can detect darker comet that many hunters miss.


Tue Aug 8

The saying of e10 days after the end of the rainy seasonf just fits this summer. It means that clear sky continues for 10 days from the termination of the rainy season that was July 30 this year. I conducted comet hunting 6 times this month so far.

This predawn the transparency was pretty good, though the time between moonset and the beginning of the twilight was only 30 minutes. I began to sweep the southeastern sky at 2:30 am, when the moon was still at the western sky.

The field of the telescope was rather bright with low contrast due to the moon light, and it made difficult to split faint double or a multiple star that looked like a comet. I sometimes stopped the motion of the comet seeker and peered into the comet-like object or must change eyepiece to confirm if it was actually the double or the multiple star with higher magnification. For this purpose I use Naglar 12 mm with 170x.

The field became darker and the contrast was getting higher as the moon declined. It was easy to split faint multiple stars after the moonset because of dark background.

I caught several galaxies in Cetus and Eridanus. I wonder how far these galaxies were, and if dinosaurs were alive when the light I saw left the galaxies. One of the galaxies I observed was M77 that is 65 million light years far (The Night Sky Observerfs Guide, Willmann-Bell Inc.); this light left for us just when dinosaurs became extinct.

Stars in our galaxies, quite a few of which went through in the field, are much closer; they are hundreds of or thousands of light years. I felt 3D effect by imagining the distance of those objects.

Again, the S/N (signal and noise) ratio became low. This time it occurred not by the moonlight but by the twilight. It is full moon tomorrow, but I could enjoy comet hunting this predawn since the moon was at low right declination and it set early.



Sun July 30-Mon July 31


The rainy season has finished today, July 30. It was clear in daytime but when I arrived at the observing site at 8 pm, cloud covered the most part of the sky. Around 9 pm a cloud gap opened and it began to spread. I tried to observed 177P Barnard that approaches us after 117 years since last return.

First, I trained my 46 cm comet seeker on the comet with the digital setting circles but its accuracy was not good near the zenith and I could not spot it in the telescope field. Then, I referred to the finding chart that I printed out in my house using MegaStar Ver.5. However, I could not identify the asterism in the 5 cm finder scope. I tried again and again, but I could not. I spend more than 10 minutes for it without knowing the reason. Something was wrong. At the next moment, the field became gray due to cloud cover. What a nightmare! I had been looking forward to observing this comet!


I waited for the next chance for half hour and luckily again a cloud gap began to grow. It extended to Hercules where 177P was. The asterism in the finder scope was different from the printed chart again however, and I doubted the chart. I opened the Uranometria 2000; I found that the asterism on the Uranomertia was right and the MegaStar 5sf was wrong! Anyway, I could train the telescope on the comet using Uranometria 2000 and conducted the observation.

It has the magnitude of 8.7 with 9f diameter and DC 2. It was very large and defused object. I guess the surface brightness was 12 th magnitude, and it was a rather difficult object with 46 cm telescope. M. Tsumura reported he could observe 117P with 4.5 cm binocular. Defused comet like this is easily detected by a small binocular or telescope but is difficult for a large aperture.

Letfs get back to the star chart. Why was MegaStar 5 wrong? It turned out that 6 th magnitude star, Her 56, Tycho ID T 2063:1212:1, was superimposed on the printed name eBarnardf, which I could not distinguish at the site with a red LED light.
The field activity has unexpected difficulty like this at all times.

177P_chart
The first character eaf in e Barnardf is superimposed on Her 56, 6th magnitude star.
A circle indicates the field of 46 cm comet seeker with 68x, 1.3 degrees.


I slept in my car and got up before 2 am. As the forecast predicted, the amount of cloud was less. I began to comet hunt from the southeast where there was no cloud. I could catch a few 12th magnitude galaxies but could not 73P Schwassmann-Wachmann.

I was satisfied with an hour and 20 minutes comet hunting session since June 13.

Fri Jul 14

There was a storm at the night of June 30, and the total rainfall amount in June did not record its minimum for the 90 years as I described on June 29.

This evening the sky was fine with a small amount of cloud. Before leaving my office I tried to check the time of the end of the twilight and the moon rise. I thought that there must be enough dark sky period to do comet hunting this dusk, since I knew it was the full moon a few days ago. OK, the Astronomical Pocketbook read there was more than one hour!

After I got home and finished supper I left home for the upland to comet hunt. On my way to the observing site the coverage of the cloud began to rise and I noticed the top of some mountains were in the clouds.

Anyway, I arrived at the site and assembled my 18 inch telescope. What a wonderful activity to assembling the telescope hoping for the starry night that I could enjoy in half an hour! I especially felt so, because I had not swept the sky since June 13 due to nasty weather.

When I completed the assembling, cloud spread all over the sky; all the stars I could see in the sky through the cloud were Arcturus and Jupiter. In a little while those two stars disappeared. I spread the plastic sheet on the ground and lay down on it to wait for the emergence of the cloud gap. Warmness of the ground was comfortable but no stars appeared in the sky. I disassembled the telescope and left the site around 9 pm after all.

Usually, the weather condition in the rainy season is worse than in winter when we have a few meters of snow here on the Japan Sea side; I could comet hunt at least once per month in midwinter.

Wed June 29

The rainfall amount this month is the smallest since the beginning of the observation in 1917 in my workplace, Tohkamachi Experimental Station, if no rainfall would be observed tomorrow. Even so, there were few nights that the comet hunting was possible: I could do it only twice this month. The sky is covered with thin cloud tonight also, though the forecast predicted clear sky.

It was exciting that LINEAR spotted P/1889 M1 (Barnard 2) after 117 years' separation one week ago. How wonderful it is the comet was discovered unexpectedly after over one century of the first discovery. If the discovery had been made by an armature, especially visually, the story would have been much cooler!

Greater dream for most comet hunters are to discover a periodic comet or a great comet. There still must be such chances for every hunter.

I am inpatient for the clear sky.

Sun Jun 11

I could sit back and relax in the bed at predawn on this week end, because it is full moon today.

This month it has been depressing weather and I could comet hunt only once so far, on last Sunday June 4, in spite of optimistic forecast as the end of last month.

I wonder if the amount of cloud is boosted by the Global Warming, and it gives rise to the number of cloudy days. I think no meteorologists can prove whether this scenario is correct or not due to lack of data and incompleteness of the modeling. Anyway, reduction in the number of clear days is disappointing.

Another bad news for me is that the new solar observation satellite will be launched next month: STEREO (Solar TErrestrial RElations Observatory)
http://stereo.gsfc.nasa.gov/mission/mission.shtml


According to Karl Battams, via Hirohisa Sato OAA-comet mailing list, coronagraphs are equipped in the satellite and images will usually be taken as +90/0/-90 -degree triplets. The instruments would be a new threat of comet hunters, especially low altitude hunting near the sun.

You do not know what will happen until the operation begins. However, it is yourself who judge if the new satellite really threats you or not.

Winners never quit, and quitters never win.
-Ted Turner (U.S. broadcaster and sports executive, 1938- )


Sat May 27

The forecast said clear sky prevails at this predawn and I got up at 1 am and again at 2 am. It was cloudy, however. Ironically, the sky is very clear this morning; probably since the sunrise.

Yesterdayfs predawn, the circumstances was similar: I went out of the bed at 1 am but no stars were twinkling on the sky, although the prediction claimed it would be fine.

At the predawn of Thursday also, the situation resembled that of today but it was better: the forecast predicted clear sky and I got up at 1 am but in vain. I looked at the sky again at 2:18 am and it was clear! The twilight began at 2:43 am and there was no time to assemble my 18 inch telescope and to move to the usual observing site where the sky condition is superior. Instead, I assembled my 8 inch reflector in front of my residence. I could search the lower part of the eastern sky with 31x for 40 minutes.

The forecast in this season is difficult since a slight motion of the Rainy Season Front changes the weather drastically, though the mesh-weather forecast system in our country is one of the best in the world, I believe. 

The Japan Meteorological Agency (JMA) made a public announcement yesterday that the southern part of the Kyusyu Island, the southwestern Japanese Island where comet hunters Utsunomiya and Kudo live, entered the Rainy Season. Hyakutake also lived this Island. I guess that the area I live would do in a couple of weeks but Japanese Rainy Season does not necessarily bring constant rainfall; usually it includes some clear days. I have to watch out for the weather not to lose the chance.


Wed May 10


Moon set at 2:54am and the twilight began at 3:01am. I did not have enough time to do three kinds of activity: taking photos, visual observation, and comet hunting.

At 2:30am I had assembled both 18 inch telescope for comet hunting and an equatorial mount for taking some photos of 73P Schwassmann-Wachmann fragments. Fragment C approached Beta Cygni, Albireo and fragment B passed near Alpha Lyrae, Vega. As a result, I failed to fragment C due to out of focus.

I am trying astrophotography not only just for fun but for practice: when I spot a new comet, I want to confirm it by photos.

Fragment B that busted was easily visible by naked eye and looked over one magnitude brighter than M13: It must be magnitude of 4th to 5th and also looks brighter than Epsilon or Zeta Lyrae in the photo.@However, visual observation I made last evening by 5 cm binocular resulted in magnitude of 6.1 and rough estimation at this predawn was almost the same.

Many observers estimated it as 6th magnitude using binoculars. This sort of discrepancy, including the differences in magnitude estimation between visual observation and CCD, has been pointed out by many comet observers but the exact cause is unknown.

I could spend 35 minutes for comet hunting from 3:10am.


Thu May 4

I have arrived at the observing site at mid night, because I tried to astrophotography with guiding for the first time since my boyhood; I took the last one more than 25 years ago. Off course, tonight I aimed at 73P Schwassmann-Wachmann Component C and B.

The results were not satisfactorily due to poor alignment of polar axis telescope (not polar alignment itself), and lack of focusing skills for digital camera lens.


73P Schwassmann-Wachmann component C, 2006 May 3.7073UT


73P Schwassmann-Wachmann component B and M13(left), 2006 May 3.6784UT
Common data: Canon 20Da, EF200mm F2.8 (F2.8), three minutes exposure, ISO 800, Takahashi Sky Port portable equatorial mount. Images were cropped.

After taking photos, I observed a series of this comet.
I could barely observe 73P Schwassmann-Wachmann C with naked eye, but could not 73P-B. 73P G was very diffuse, though 13th magnitude, and just the limit for my instrument@(18@inch). I have to turn the azimuth axis of my telescope 180 degrees for a short time during the observation of this comet, since it had just passed the meridian near the zenith! It was hard work and for me this was the first experience. I also tried 73P R but I could not.

After observation, I began to comet hunting at 2am and finished at 3:30am. Today is a national holiday and I can have enough time to sleep after dawn.

Thu Apr 20

Whizzing wind woke me up at 1:50am. The sky was clear. I hesitated to comet hunt with 18 inch telescope because of the strong wind. However, it seemed to be weaker with time and I decided to assemble my 18 inch.

The sky was bright due to last quarter moon and the southern wind was dry and warm. I started search from Gamma Cygni toward north. Scintillation was extremely bad and it must be caused by the strong wind in the upper air. The star images were distorted and looked fleshy that made this comet hunting session uncomfortable: each star looked like a comet.

Suddenly, at a quarter past 3am, scintillation became much better. How easy and cool to search! The sky area I covered this predawn included the position of C/2006 A1 Poimanski that must be reduced to 10th magnitude, but I could not catch it due to twilight and moon light.


Fri Apr 13

Kazimeras Cernis, a Lithuanian comet hunter, sent me a copy of book written by an American comet hunter Don Machholz entitled gA decade of comets: A study of the 33 comets discovered by amateur astronomers between 1975 and 1984h. I  exchange email with him every now and then but it came unexpectedly.

It consists of 111 pages, including description on the time, magnitudes, positions, the statistics of discovery and orbital elements. Tsutomu Seki had ever written similar booklets in Japanese, though some Sekifs books features spiritual point of view; they are fable rather than scientific reports. I guess his literature was not known in foreign countries, unfortunately. Those kinds of publications often feed and encourage comet hunters. Actually, I was one of them. If it were not for Sekifs book, the number of Japanese comet hunter would be much less.


A copy of Machholzfs book.


Sat Mar 25

 I was ready to comet hunt at 2:45am but before it, I observed 73P Schwassmann-Wachmann component B that was darker than the main component C. The result is cited here. I could not notice the component C at 68x and increased magnification up to 170x. Then, it was apparent at a first glance. After brightness measurement, I changed magnification to 68x again. Now, the component B was easy to observe with 68x. To find a known deep sky object or a comet is one thing; to discover unknown one is another.

Howt graceful@the component C was!  The tail was 6 arc minutes in length that was the same with the component B. But I must make it a snap. I just watched it and soon after that began to comet search.
It took 25 minutes to observe 73P that was long time for a comet hunter at predawn. I always hesitate whether I really@should observe comets or not, especially when I conduct brightness measurements because it is time consuming work. However, regardless of doing brightness measurement or not, I never regret to observe a graceful comet that gives me an impression of subtle and profound.

Sat Mar 18- Sun Mar 19

I attended the 36th Annual Comet Conference in Nishiharima Astronomical Observatory, Western Japan, where 2 m (79 inch) telescope, Nayuta, had the first light last year. This is the largest telescope at home.

The Conference began in Saturday afternoon and closed at Sunday noon. There were 44 attendees including both professional and amateur cometary astronomers. The Conference consisted of 8 oral presentations, 4 sectional meetings and 73P Schwassmann-Wachmann session.


The opening statement by the chairperson of the Annual Comet Conference management committee, Jun-ichi Watanabe of National Astronomical Observatory Japan. Far left: the chairperson of Local Organizing committee, Atsushi Mori of the Nishiharima Astronomical Observatory.


Unexpectedly, I was the only comet discoverer among the attendees and was assigned to the chairman of the sectional meeting on the comet hunting, in which 11 persons attended. Six out of 11 attendees including me are active comet hunters. On top of those six hunters, one is planning to start comet searching and making a comet seeker, and another may resume hunting.

Two hunters are searching comets with DSLR (Digital Single Lens Reflex) camera or CCD and others are visual comet hunters. There are two Fujinon 15 cm binocular users, one Miyauchi 14 cm and Nikon 12 cm binocular user, respectively. Others are reflector users but some use both a binocular and a reflector.

For most hunters light pollution is a serious problem and they make much effort to compensate for it
; one said that he drove two hours to the observing site. Another remarked that he had supper and took a bath and then drove to the observing site to sleep in his car and got up at predawn. After his comet hunting session, he heads for his office to work!

Photographical hunters, especially CCD users have an advantage that they can comet hunt under moderate light polluted conditions.
Yukio Sakurai who has discovered many novas shifted from a film camera to a DSLR. He said that it is easy to take photos with DSLR and he took a lot of images but it is time consuming to check all the images.

Most of the comet hunters without discovery are unknown and you do not know how many hunters in this country. Some people say there are about one hundred active comet hunters in Japan, and  I think it is reasonable judging from the number of hunters attended this Conference.

The next yearfs Conference is held in Niigata Prefecture, and I was assigned to the chairperson.


2 m telescope, Nayuta with me
This telescope is gphoto visualh and we could observed Moon, Jupiter and 73P Schwassmann-Wachmann through thin cloud.


Domes of 2 m telescope Nayuta, and 60 cm reflector (far right).


Sun Mar 5

It is bright! At last I could observe C/2006 A1 Pojmanski at this predawn.

Yesterday, I got up at 2:30am and 3am but was clouded out. Then, the clear sky spread after sunrise yesterday and has continued since then.

Today, before comet hunting I observed 73P/Schwassmann-Wachamann 3 and P/2004 VR8 LONEOS. 73P was 12th magnitude and the tail was apparent with 18 inch 68x, while VR8 was only 14th magnitude and at a first glance with 68x I was not sure if the image I focus on was actually the comet. I confirmed it with 157x.

Seiichi Yoshida observed both 73P-C/Schwassmann-Wachmann 3 as magnitude of 12.3 and 73P-B/Schwassmann-Wachmann 3 as magnitude of 14.4 but what I observed was 73P-C. I had not prepared the finding chart of 73P-B.

OK, I started comet searching session at 3:30am but there was thin cloud at the low altitude and the transparency was not very good. The rating was 3/5 when 5 is perfect. My telescope was trained at some 10 degrees south of Altair and I swept the sky vertically so that I could catch C/2006 A1 during the session. After detecting NGC6781, no comets like objects were observed after a while. Suddenly bright comet crossed the field with a straight tail!

The length of the tail, type I, was about 2 degrees and there was the type II tail at the position angle of a few tens of degrees clockwise from the type I tail. The type II tail was very short and looked like a part of the coma that was ejected. I could also recognize the type I tail by a 8x50mm binocular.

After I enjoyed C/2006 A1 cloud in the eastern sky become thick and I took 10 minutes break. I found there was cloud gap at Soc and swept there. I completed the session at 5:20am.


Sat Feb 25

Impressive predawn!
The first half of todayfs comet hunting session I caught one dozen of globular clusters in Scorpion and Ophiuchus, and the latter half I enjoyed splendid star field in the Summer Milky Way in Cygnus.

I had set an alarm clock at 3am, two hours before the beginning of the twilight, but I wake up at 2:25am. I drove to the usual observing site where snow depth reduced to acceptable level. Just after one hour of getting out of bed, I completed assembling my 18 inch telescope and began to search from M4, Scorpion. A lot of globular clusters that I met welcomed me for a long absence.

A few minutes after 4am, the light in a ski field had turned on that caused serious light pollution in the south-eastern sky. Skiers from Tokyo Area come to ski to this area at predawn.

I trained my telescope to the north-east and continued to search: the Summer Milky Way in Cygnus touched me, too. Venus and the crescent Moon rose and some time after the twilight began, I tried to observe C/2006 A1 Pojmanski. However, the mountain near the horizon intercepted the comet. Instead, I enjoyed Jupiter with a binoviewer and was also impressive like all the objects I observed this predawn! Apparently, observing by two eyes reveals more details of Jupiter than by a single eye.


Fri Feb 10

Temperature was -9 degrees in Celsius. I began to comet search at 4:40 am, 20 minutes before the moon set and 30 minutes before the beginning of the twilight. The summer constellations rose already in the eastern sky.

I could comet hunt only once last month due to tight schedule, heavy workload and snowy weather. On January 30 the sky condition for comet searching must be excellent but I was in Nagoya area@to give scientific presentation as a forest hydrologist. Since last comet hunting session I had gotten up at the predawn a few times expecting clear sky, but in vain.

That blank makes todayfs hunting session impressive, even though some globular clusters I saw in Ophiuchus was not well resolved and stars in the star ground in Sagittarius never looked pinpoint image because of low altitude and poor scintillation.

As twilight proceeded the Summer Triangle rose in the northeast and I completed the hunting session after Venus crossed the field.


C/2006 A1 becomes bright in the Southern Hemisphere. In my opinion and I believe most agree with me, the naming of C/2006 A1 gPojmanskih is inappropriate in reference  to the discovery story. It should be named ASAS (The All Sky Automated Survey).

Thu Jan 12

The Disaster Relief Act was invoked in my city and surrounding area about a week ago. At the elementary school next to my office Japanese Army (formally called the Self-Defense Force) removed snow cornice on the roof. I thank them for their activity again: they came to my city about a year ago for the rescue activity of the Mid Niigata earthquake in 2004.


Tue Jan 10

Yesterday, clear sky spread and luckily, it lasted until this morning!

Off course, this is my first comet hunting session this year. Temperature: -8 degrees Celsius. I decided to comet search in front of my house on the snow where a snowplow pushes snow out to a paddy field.

It took a lot of time to assemble my telescope and to prepare hunting under such low temperature on snow. In addition to that, digital setting circles did not work well; I tried to fix stars twice by aiming at Spica and Polaris but indicator showed error messages. I wandered if I got back my house and replace the digital setting circles with extra one. At the next moment, I found Vega at low latitude and tried to do again by combining Vega with Spica. This time it was OK! What a relief!

I began to comet hunt at 4:20 a.m., one hour after I got up. After a while, dew, caused by my breathing, condensed on the eyepiece and I was forced to wipe it. Then, I powered the heater up than usual and after that it never occurred: Kendrick Dew Remover System is equipped on the flip side of the secondary mirror, eyepiece of the 2 inch finder and the eyepiece of the18 inch telescope.

When the eastern sky got brighter, I noticed the whole telescope looked white because of frost. I could enjoy one and half hour hunting capturing a dozen of deep sky objects.


Sun Jan 8

I went to usual observing site today not for comet hunting but for check the sky visibility (Photo 1). You see a crash barrier rope on the left of my car, which I dig out with a shovel. In normal winter I can observe near the horizon from this hill slope site. Now snow depth is 3.5 m (11.7 feet) and it hides up to 20 degrees sky from the horizon. I do not want to comet hunt at this site now.


Photo 1
Observing site with 3.5 m (11.7 feet) snow.

Cold wave still prevails nationwide and a record snowfall is observed in a lot of observing points. The chance of comet hunting seems scant this winter, especially here in Japan Sea side.

Snow depth in my city, Tohkamachi (or Tokamachi),  has reached 3 m (10 feet, Photo 2-4) but this value itself is not surprising: The highest one was 425 cm (14.17 feet) that was observed in 1945. The problem is that it is too early  and that it must increase from now on.
The snow depth chart from 1917 to 2005 in Tohkamachi (observed at my workplace) is available here (pdf file) and the latest snow chart is here (lower right).


Photo 2
A girl has crossed the road and eentersf a sidewalk. If it were not for snow, it would have been mere sidewalk; however, she has to enter there due to snow. Taken on Jan 7.


Photo 3
A man is walking on a pedestrian crossing. The snow wall in this photo is the same with Photo 2 but it became higher. Taken on Jan 8.


Photo 4
A snow cornice on the building developed and seemed dangerous. Snow on the shopping arcade and a city house was plowed many times but a ferro-concrete building does not. Now snow weight is 800 kg/m2 that is approaching to the structural limit for the ferro-concrete building, 990 kg/m2.


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