Monday, June 14, 2010

Comet McNaught!

As an amateur astronomer, I have always found it much easier to stay up late observing than to go to bed on time and wake up in the middle of the night to observe.   For the past several nights I have wanted to wake up around 3 AM to check out Comet McNaught (C/2009 R1), which has been surfing its way through the constellation Andromeda and now into Perseus.   This comet is making its first trip through the inner solar system, and reports had it at the threshold of naked eye visibility.  I had seen a few pretty pictures of the comet (see Gary Kronk's Cometography website, for instance) and was interested in making some visual observations. Comets are quick movers when hurtling through the inner solar system around the sun, and typically one can observe their motion relative to the background stars over a period of a few minutes to a couple hours.  NASA maintains a website with quite a bit of orbital and other technical information if you are interested.

Last night I decided to set up my Stellarvue 90mm triplet (on an alt-az mount, since most of my gear was packed up from a failed observing trip this past weekend).  I thought I would do some observing of some of the milky way treats that I have not yet observed this season, and then turn in early, leaving the scope set up for my 2:45 AM rendezvous with the comet.  I observed several Messier objects and some double stars, and decided to make a sketch of M17 (NGC 6618), the Swan Nebula before turning in.  To the left is my sketch, and on the right is a sketch made by John Herschel in 1833.

Done sketching, I set my alarm for 2:45 AM and turned in.  Turns out I did not need 2:30 AM my eyes blinked open as if on cue, and I headed outside to find the comet.  I had looked up the location previously and knew that it was in Perseus, not too far from Alpha Perseus (Mirfak).  I actually know this area fairly well as in 2007 Comet 17/P Holmes made a spectacular and now famous pass through this same area, when it suddenly and without warning brightened by a factor of over a half-million.  It was amazing through telescopes and was even visible to the naked eye.  

I had brought out my binoculars and as soon as I began looking below Mirfak, I spotted the dirty little snowball hanging out.  I removed the binoculars from my eyes, and with averted vision was just able to make out the comet.  I spent about an hour observing the comet (including drawing the sketch at left) and in that time the motion of the comet relative to nearby stars was obvious.  It is not moving quickly, but in the time I spent making the sketch I noticed a change in position.  The sketch was completed at 1020 UT (3:20 AM MST) using my Stellarvue 90mm refractor, at 63x.  The comet is estimated at magnitude 6.2 and was approximately 1.14 Astronomical Units from us, or about 169.9 million kilometers.  At the eyepiece, the comets tail was fainter than what is represented in the sketch, but it is hard for me to draw such a low contrast feature. In addition to the long thin tail blowing off the comet, there was also a small secondary tail that appeared much wider and shorter in length than the primary tail.

Dean Ketelsen, fellow member of the Tucson Amateur Astronomy Association, took the picture to the right of the comet on Sunday morning, about 24 hours prior to my observation. He posted it along with other images and his observing report on his *Excellent* Blog.  (In fact, Dean inspired this blog!).  He took the image from a lookout on Mt. Lemmon at about 7000 ft.  Dean also explains on his blog that this particular comet is in a hyperbolic orbit, and is making one pass through our solar system never to return...Even more reason to hunt it down!

An update just for kicks...I was playing around with my sketch of the swan nebula above and digitally added some sparkles to some of the stars...I kind of like it...

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