Category: Comet

Comet C/2001 Q4 (NEAT)
Sketch by Eiji Kato

Mr. Kato prepared this sketch of Comet NEAT on a pre-printed star chart.

Comet 17P/Holmes
Sketch and details by Martin Mc Kenna

Nov 3/4 18.20 – 20.00 local time.

Tonight 17P/ Holmes was a spectacular object to those lucky enough to have dark skies. This was a night of revelation for me. In the 8.5″ F/7 reflector I measured the brighter inner coma at 15′ in dia. It was a bright lemon colour with beautiful segmented ring around the perimeter like a horse shoe with bright enhancements and dark obscurations. The N side described a beautiful curve with the S section soft and broken in profile. At centre was a very faint and soft false nucleus which looks more like a well defined smudge rather than stellar in the 32mm eyepiece. The dust fan was still bright and elongated to the south where it merged into a vague void of complexity where all the finer action was taking place. Surrounding the FN was 3 dark wedge-shaped holes or pits in the region between the FN and inner coma. By sweeping the telescope back and forth I could see the green transparent outer coma for 30′ either side of the inner coma. Since this central region was 15′ across I got a total diameter for the outer coma at 75′ or 2.5 times the apparent size of the Moon. The other coma has a very sharp edge with obvious cut off point where the coma ended and the background sky began. It was a disk-like shape very much like a CD. This effect was enhanced by the stunning dark ‘lip’ which surrounded the inner coma like a jet black scarf much like what is now being picked up on CCD images. This dark collar was very well defined and by letting the comet drift across the field I could see its passage with ease as it first entered then drifted in transit across the 1 degree FOV. The shape of this feature reminded me of an ‘Arcus’ or ‘Shelf Cloud’ which marks the gust front of a thunderstorm. I observed two long Ion tails, the first to the S and the second to the SE with the first being 1 degree in length. A nice fan of multiple fine streamers spread across the void between these two long linear features where the inner and outer coma meet.

My 10x50mm binoculars have a FOV of 5 degrees. Using these I was astounded to see the coma taking up much of the field which I estimated at 3 degrees in dia or 6 full Moon diameters!!. I couldn’t believe what I was seeing and was reserving severe doubts about the whole thing until I saw it easily again with well defined edge which flirted with the eastern most stars within the large open cluster between Alpha and Delta Persei. The entire sharp dark green outer coma looked like a smaller version of the Gegenschein during the times when it can be seen as an oval glow. Further more the ‘disk’ was not a perfect circle. The southern end looked ‘missing’ as if a wedge shaped section had been cut from the coma with scissors. I recently recall one observer describing this outer coma as shaped like a Jelly Fish and this was more or less what I could see also. Extending from the void in the southern section was a long linear ray of light approx 2 degree long. I do not know if this was a long ion tail or just an enhancement along the inner edge of the coma. Confused by the whole thing I decided to delay this observation until I could confirm it myself.

Tonight (Nov 4/5) the sky was stunning and very dark. In the 10x50s I could see the same size of coma and shape as observed on the night before. However even more astonishing was the view with the naked eye on this grand night. Using my finger tips held at arm’s length I could see the entire coma extending for approx 5 degrees in dia (10 Moon diameters) with the naked eye!!!.

I now believe that any future visual mag estimates and D.C estimates will be almost impossible with any degree of accuracy but for what it is worth I will stick to my last estimate of +2.5 at D.C:7

C/2007 W1 (Boattini)
Sketch and Details by Michael Rosolina

At present, there are two comets in the night sky that bear the name Boattini. One, C/2008 J1 (Boattini), is currently moving out of Cepheus and is visible all night long. The other, C/2007 W1 (Boattini), dipped below the horizon for northern hemisphere observers back at the end of May and did not reappear until the beginning of July. To see C/2007 W1, an observer had only a short time span as the comet rose with the constellation Cetus and was soon lost in the dawn glare.

My sketch shows how W1 Boattini appeared to me through my 15×70 binoculars on the morning of July 15th. I then was able to take advantage of clear weather and plot the comet’s position over the next two mornings as it traveled to the NNW through Cetus past the 4th magnitude star lambda Ceti.

The original sketch and position updates were done in the field on Strathmore sketch paper with a 2B pencil and blending stump. I then inverted the sketch after scanning, applied 5% blur, and added the text.

Like most comets, W1 Boattini was easiest to see from dark, moonless skies with good transparency. It was difficult to impossible to observe visually while the Moon was bright, but now that Luna is on the wane, it will once again be possible to observe it. It is now in Aries, higher in the sky and visible earlier and for a longer time before morning twilight. If you get the weather and opportunity, try and observe it over several mornings to detect its motion against the background stars.

Michael Rosolina
Friars Hill, West Virginia, USA

C/2004 F4 (Bradfield)
Sketch and Details by Martin Mc Kenna

C/2004 F4 Bradfield on April 29th 2004 at 03.47 LT as seen through the 8″ F/6.3 S.Cass among the star fields of Pisces low in the NE very close to the sun. This was a beautiful comet – I could see it rise tail first over my garden trees through my 10X50 binoculars and finder scope. The white straight dust tail was 5 degrees long with a compact well condensed white/green coma and spine. However this morning was a time of surprise and discovery – as soon as I swept up the comet I was shocked to see a bright anti-tail pointing toward the sun which was not their before. This was my first observation of an anti-tail and I was among only a few lucky observers to have seen it.

Before it appeared in the morning sky the comet made for a spectacular sight in the SOHO LASCO C3 images where Bradfield could be seen completing a hairpin turn around the sun with an incredible bright curved tail. The comet looked like it was a living creature! This was the 18th comet discovered by the living legend known as William (Bill) Bradfield who found the comet close to the sun during an evenings comet search.

C/2004 Q2 (Machholz)
Sketch and Details by Martin Mc Kenna

Three jets issuing from the nucleus of C/2004 Q2 Machholz on Dec 28th at 18.22 LT and Dec 29th through the 8″ F/6.3 S. Cass at 49X. Over a period of several nights I could see the position of the jets changing due to the rotation of the comets nucleus. These jets were bright white linear, pencil thin features that were easy to see. CCD imagers confirmed my visual sighting several nights later. Machholz was an unusual comet as it stayed far from the sun, was visible all night high in a dark sky and was easy with the naked eye. Not all comets are so considerate as many bright new comers remain hidden within bright twilight close to the sun skirting the horizon.

I was delighted to be the first in Ireland to track down this comet – my first observation was made late on a winters night before Christmas using a Meade 3.5″ ETX from a nearby pitch – a location which let me see low down into the eastern sky. I found the comet quickly above distant rooftops and in good time to as 20 min’s later dense mist and murk obscured the this sky sector for days afterward!