The Evolution of Comet 17P/Holmes Following the Outburst on October 23/24, 2007
Click on any image below for a higher resolution image - Composite comet images were captured with a Tele Vue TV101 Apo refractor and a DSLR at prime focus, 30 second exposures at ISO 800
I can't quite remember how I learned about the outburst of Comet 17P/Holmes; all I remember is that the amateur astronomy alerts were going off. I checked www.spaceweather.com which is usually on top of things and discovered that a relatively obscure comet had come to life in Perseus! I believe that someone in the Canary Islands initially spotted an unprecedented brightening of the comet and that was quickly reaffirmed by others. On hearing the news, I grabbed my binoculars and headed outside. I looked up at Perseus and noticed something that didn't look right; a new star was situated near the star Mirfak. I looked at this new star with my binoculars and could see that this was not a pinpoint stellar object. It looked like a fuzzy star, similar to what a globular cluster looks like through binoculars.
The full moon was blazing not far from the location of the comet which washed out the skies significantly, but the comet was easily visible to the naked eye. I quickly set up my Vixen GP mount and Tele Vue TV101 Apo refractor and observed the nucleus and coma of Holmes for the first time. Initially, the comet had the appearance of a planetary nebula, which looks like a shell of expanding gas surrounding a central star. It was truly amazing that I was observing a comet that 24 hours ago was totally invisible to only the largest telescopes and now Comet Holmes had brightened from magnitude 17 to approximately 2.5 in less than 24 hours. This is a brightening of 500,000 times or more! It was now easily visible to the naked eye in major light polluted cities.
The composite comet images above are the culmination of hours of effort in less than ideal weather conditions. November is notoriously cloudy in Southern Ontario, Canada and I am truly surprised that I could image the comet so many nights in a row between November 1 and November 6. I had to deal with a thick ice fog while capturing the image on November 10th which coated my astronomy gear with a layer of dew that froze on all exposed surfaces. On November 5th and 6th, I was covering up the scope, mount and camera with plastic bags due to the high winds and blustery wet snow, but somehow miraculously a clearing occurred briefly on both nights that allowed me to add pearls to the image I like to refer to as the "String of Pearls".
The views of the comet through our 18" Obsession telescope was amazing! I was surprised at how many background stars I could see through the coma of the comet. On November 10th the comet almost completely fills the field of view when observing with a 26mm Nagler eyepiece.
What's next for the comet? Without any further outbursts it will continue to expand and become so diffuse that it will fade away as it continues its journey heading away from the Sun. The comet, which is in orbit between the planets Mars and Jupiter has already passed its closest encounter with the Sun in its seven year period. Will the comet outburst again in its next swing around the Sun? We will have to wait another seven years to find out.
Lauri Kangas, November 19, 2007