Monday, May 31, 2010

Old Business

On the last dark-of-the-moon a few weeks ago, I headed west towards Kitt Peak for some astro imaging. It seems like forever since I've had an observing session with the C-14 and digital camera, and with some clear Arizona skies, it was time! In the springtime, multitudes of galaxies rule the sky, so there were a couple groups that easily fit into the C-14 plus Hyperstar combination.

I usually arrive to set up just before sunset so that the telescope can be assembled, allow to cool a bit, then the photographic gear installed and focused before twilight so I can do "twilight flats" to help calibrate out unevenness in illumination. While the sky was fantastically clear, there was a bit of a blustery breeze that came up and irked me into the evening... One of the drawbacks to observing at high elevations, the wind can come out of nowhere, even though it is calm on the desert floor.

First up was the group of galaxies that are gathered around Messier 106 (NGC 4258) in Canes Venatici (Hunting Dogs), not far from the Big Dipper in Ursa Major. I "discovered" the galaxy a few years back when doing the springtime messier Marathon - it has a bright core, but a large extended fainter halo that shows up nicely in an exposure. There is an abundance of galaxies scattered throughout the frame, and the edge-on spiral below right may be a companion (NGC 4217). M106 (number 106 in Charles Messier's catalog) is about 24 million light years away. Of course, all the stars visible in the exposure are much closer to us in our galaxy. The streak of light through the frame is a satellite that moved through the exposure, still lit up by the sun even though dark at my location... The blowup at right actually shows a fainter one as well. This exposure is a cumulation of about 25 minutes of exposure on 9 frames that were added together with the Canon 20Da.


I then moved down to the constellation Leo and shot the "Leo Trio" of galaxies, made up of M65, M66 and NGC 3628 (CW from lower right), all about 35 million light years away. This grouping is a favorite of visual and photographic observers and never disappoints. Unfortunately, in moving south of the zenith, either the angle of the scope changed, or the wind picked up and it was nearly impossible to keep the guide star centered on the cross hair of the guide scope. After the 9 minutes of 3 exposures shown, I gave up - it was just too frustrating. The enlarged images caused by the wind are evident. As a result, even though it was a clear night, it was an early night. I could have done some wide-angle imaging, but it was hours for the Milky Way to rise, and small galaxies don't show up well with just camera lenses. So I was home by midnight and got to see a bit of Craig Ferguson before turning in. A fun night just to get under the stars, but frustrating as well. It isn't always equipment issues or clouds that can mess up your plans!

3 comments:

David A. Harvey said...

Nice! Do you have any autoguiding capability with the C-14 Hyperstar system?

Dean said...

Hi Dave-
Yes, I have an ST-4 autoguider, but I'm old school and enjoy occasionally guiding manually, especially when I do "long exposure noise reduction" and get half the time off...
-Dean

Anthony Vodraska and Anita Gilbert said...

Great images Dean! I am always impressed with what you capture. It makes me want to run out and buy a C-14 but then I remember it is your skills that make the difference. Can't buy that. Oh well, I will just enjoy your blog postings.