Observations Of 17P/Holmes Comet, October 2007
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This web page documents my observation efforts of comet 17P/Holmes in October of 2007. In October of 2007 mundane comet 17P/Holmes, known about since way back in 1892, made history. In a virtual explosion of magnitude, it brightened from obscurity to become a naked eye comet. As comets often do, it has captured the attention and anticipation of astronomers world wide. It captured my attention also, and I present on this page the drawings I made of the comet, plus one photographic effort. I apologize for the fact that my first sketches were a bit crude, due to my lack of preparation in the first couple of observations. But I believe I got my act together, and have presented a reasonable historic view of the development of the comet. |
The comet has become pretty diffuse now, and is getting more difficult to see. Maybe it will go back to obscurity. Maybe it has more surprises to reveal.
For comet updates on comet activity, check out Weekly Information about Bright Comets and Comet Chasing.
For most comet observing, you don't need a behemoth telescope. A 2.4 inch to 6 inch will do nicely. Preferably a telescope with a wide field of view, such as a short focus Newtonian.
My two favorite instruments are a pair of 15x70 Barska binoculars and a 6 inch f/5 Newtonian. Both have the wide views that make comet observing enjoyable.
Want to know more about observing comets? An excellent place to start is to obtain a book on comet observing, such as David Levy's Guide.
First Observations - 10/27/07
Shown at left is a bit crude representation of the comet as I saw it on October 27, 2007. The view was through my 15x70 Barska binoculars, which gave me a very pleasing view.
To get the steady view I needed, I mounted the Barska binoculars on my camera tripod as illustrated on my Binoculars Tutorial.
What I saw on that evening was an image that I describe as a street lamp through a fog. A bright glow in the center surrounded by a soft glow. The bright spot seemed just off center, and one side of the larger glow faded off quicker than the other.
Getting Serious - 10/28/07
On the next evening I decided to get serious, and make a more detailed sketch. So I moved up to a larger instrument.
I set up my 6 inch f/5 Newtonian. Examining the comet at about 100x, this is what I was able to observe.
The view had not perceptible changed, except I could see a couple of stars gleaming through the haze surrounding the comet nucleus. That made the view quite memorable.
I sketched also the surrounding stars that I was able to perceive.
Through the f/10 - 10/29/07
On the night of October 29, I decided to switch to my 6 inch f/10 Dobsonian for a view.
Again observing with a magnification of about 100x, this drawing is what I observed. Again I was able to see a star gleaming through the haze of the comet, as well as a few surrounding stars.
The drawing would suggest that the comet is getting more diffuse. Frankly, I think this is a matter of getting my sketching legs under me.
Back on the Trail - 10/31/07
I missed a day and didn't get out to view again until the 31st.
For this viewing, I went back to my 6 inch f/5, observing at 75x.
Trying to refine my sketching technique, This is what I came up with.
Finally A Clear Night - 11/08/07
I've had the most exasperating weather lately. Thin, high flying clouds day and night. It probably helps considerably with global warming, deflecting some of the suns relentless rays.
But it's the beans for observing stars and comets.
I was finally able to set up my 6 inch f/5 on the 8th and get another view. From what I could see the comet size wasn't noticeably different, but it looked more diffuse. The central brightness was less distinct.
I didn't happen to view any stars through the comet cloud, but saw a dim one just off the edge at 1:00 (direction-wise).
I'm hoping the observation was valid, and that the apparent diffuse nature wasn't caused by one of the pesky high-altitude clouds.
A Try For The Tail - 11/11/07
I got a chance on the 11th of November to view comet 17P/Holmes again.
On this occasion I viewed it with my 15x70 Barska binoculars, my 6 inch f/5 Newtonian, and my ETX 90M. It showed well in all instruments, but was most pleasing in the faster instruments. That is, the binoculars and the f/5 Newtonian.
I was unable, however, to make out the ion tail. My view was pretty much what I'd seen on my previous outing. So much so that I saw no need in making another drawing.
Some years ago I was able to capture clearly the dust trail and ion trail of Hale Bopp by using a piggyback camera mount on a Meade refractor. The refractor was an import model with only fair optics, but did have a simple single speed clock drive.
I modified the drive on that telescope to give an easy off and slew push button control. The slew being about double the normal speed, accomplished with bypassing some of the control electronics.
With this simple modification and a piggyback camera mount I was able to get rather good results on Hale Bopp, viewable at 2 Inch Lens astrophotography.
I added a "how to" project to my webpage at Piggyback Mount to illustrate a method of making the simple piggyback mount I use.
I will be using the same mount, clamped to my 6 inch f/5, to try photographing 17P/Holmes. A little bit of clear weather and a couple days to get my film used up and processed is all I need.
First Photos - 11/11/13
Shown above is my first effort at capturing the Holmes comet on film. It's not a great image, but the best I was able to do on the first occasion. This is a crop of the center 1/4 or so of the original photo.
I used 200 ASA Kodak color print film. The exposure was about 5 minutes using the apparatus I describe on Piggyback Mount. I was not able to pick up any comet tail with any of the photographs.
The telescope alignment was pretty good, and the drive worked well. The main problem with my first attempt is that I actually over-exposed for the amount of sky glow in my area. I need to go for exposures of 1 or 2 minutes.
I used a 135mm telephoto on my Exa. Because the Exa does not have a focal plane shutter, it causes a little vignetting, or darkening of the edges of the image. This only happens with telephoto lenses, and is usually not noticeable with star photos. But since I over-exposed, the sky glow effect shows the vignetting.
On my next outing, if I get one, I'll use my old Pentax with a 270mm telephoto. This will gave a better image size.
Another View - 11/28/07
I finally got a break in the weather and took out my 7x50 and 16x50 binoculars in an effort to spot 17P/Holmes. It took a bit of time because the comet had moved significantly since I last examined it. On this occasion the comet was about 10 degrees higher in the Western direction than the star Mirfak, the brightest star in Perseus. I was surprised by the amount of movement.
I started the search with my 7x50 binoculars because they had the greatest field of view. With binoculars, field of view is often indicated by the width of the region in view at 1000 yards. For my 7x50s, the indicated field is 372 feet at 1000 yards. By dividing the indicated field (expressed in feet) by 52.4, I can get the angular field of view. For my 7x50s, this is about 7.1 degrees.
I already knew that the comet was moving generally upward (eastward) through the constellation Perseus, so I began by sweeping upward from Mirfak. I found the comet, and was happy to see that is was still easily visible in my 7x50 binoculars. But I was quite surprised how far it had moved.
I took another look at the comet, now located, with my 16x50 Bushnell binoculars. The field of view indicated on the Bushnell binoculars is 168 feet at 1000 yards, which converts to 3.2 degrees.
The comet has a very extensive size now, covering nearly 1/3 of the field of view of the 16x50 Bushnell binoculars. With that observation, I estimate the apparent size of the comet dust cloud to be just under 1 degree.
I did not re-draw the comet, because other than being larger and a bit dimmer, it does not look particularly different than my most recent drawings. It is interesting to note, however, for how long the comet has been visible in binoculars, and how easily resolved it is. It illustrates the usefulness of binoculars for comet observing.
Update - 12/02/07
The Holmes comet is making its way toward Algol. In dark skys it is still just visible as a smudge to the naked eye. I was able to see it easily with my 7x50 binoculars. It is large enough now to make a nice object in the 7x50 field of view.
The outer regions of the comet are fading significantly, so the outer regions are no longer distinct.
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