Monday, June 14, 2010

Another Comet McNaught!

It was just a month ago that I posted about Comet McNaught - C/2009 K5 McNaught to be precise. Well, after a long day of work on Saturday, I relaxed at home in the evening and was tempted enough by some of the photos I'd seen to track down the new and improved Comet McNaught, this one designated 2009 R1. Realize Rob McNaught is working on a comet survey for NASA, and since he represents one of the few surveys in the southern hemisphere, he discovers a lot of comets, 9 of them in 2009!

This Comet McNaught (2009 R1) is making a very nice appearance as most comets go. It is currently barely naked eye, but only from a very dark sky. It was also closest to the earth this last weekend, but still 105 million miles from Earth, so it is small. But it does sport a nice skinny tie of an blue ion tail as it moves swiftly across the morning sky, a few degrees a day.

So after staying up for Saturday Night Live, I packed and headed up Mount Lemmon for my pre-sunrise encounter. I got up to San Pedro Vista, above 7,000 feet elevation, and was greeted by the brilliant Summer Milky Way high overhead, with the glow of Tucson reduced to a southern glow. My quarry was going to be rising in the NE just an hour or so before morning twilight started at 3:30. After setting up the equipment, a G-11 mounting with both my 80mm Meade F/6 APO and a 200mm Canon lens, I had time to shoot a few frames of the Iris Nebula in Cepheus (NGC 7023) before the comet got high enough to see.

I finally spotted it in binoculars - a little aqua fuzzy spot with the barest hint of a tail. But when the cameras were unleashed, a quite nice comet was revealed with the long blue ion tail sweeping out of the frame past open star cluster NGC 1245. I followed it for about a half hour before the sky started brightening right as predicted. When the rush to take images was finally over and I looked at them in detail, the comet was moving so swiftly it is difficult to stack the images properly, so I'm showing 2 images - a single 2.5 minute frame with the 80mm, and a stack of 7 frames with the 200mm, but stacked to follow the comet as it moved, so the stars make a dashed line. This image is stretched (perhaps too much) to show the extent of the ion tail (mostly CO+ and OH+ pushed back from the nucleus by the solar wind). There is shorter dust tail visible too off to the right, where the heavier dust particles and molecules are less affected by solar wind, but left behind by the comets motion.

The comet will continue to get brighter, but also nearer the sun, and may be visible for a short time in the early evening after sunset before moving into the southern sky. If you are not an amateur astronomer, you might want to skip this one, but if you enjoy tracking down these denizens, it might reward you well!

Update: I decided to add a wide-field image of the comet as it rose above my horizon Sunday morning. This exposure was taken with a 20mm lens at F/2.8 for only 45 seconds with the Canon 20Da. Click on the picture to load a larger image with labels for the comet, constellations and bright sky objects.

One more thing - this comet has a hyperbolic orbit. What does that mean? Well, with an eccentricity of 1.0004, it means this comet is coming through our solar system for the first time. It is NOT in orbit around the sun, it's velocity is too high, so after missing our star, it continues on, never to return!

2 comments:

David A. Harvey said...

Really nice Dean! You can see the tail in the second shot stretch out to more than 2.2 degrees! I was shooting at the same time you were from my house - even a 42 minute stacked exposure wasn't enough to get as deep as you got here. Kudos!

Alan said...

Nice images Dean- I was out this morning observing this pretty comet