CGE Pro Returned – AT10RCF Back in Service!
Back in November I picked up an AstroTech AT10RCF – and a hefty mount to hold it aloft, the Celestron CGE Pro. After a brief test and review, the mount promptly killed itself. Perhaps it was a combination of excessively low temperatures — in the teens — or perhaps it was an extension of the ‘new gear astronomy curse.’ Either way, I sent it back to Celestron for warranty repair work. Celestron was very friendly during this whole process, including several calls to update me on status. While it’d be nice if nothing happened in the first place, I understand that sometimes bad things do happen. And great service and support is what it takes to make up for those rare cases.
Nonetheless, the mount arrived back home earlier this week. Re-invigorated, I mounted the beautiful carbon-fiber bodied AT10RCF on top and took it out for a more well deserved spin. As before, I started with a simple star test — Mizar and Alcor, the friendly pair in Ursa Major. It was very exciting to see that Mizar A and B components, while not individually resolved, are pretty obviously paired. Given a separation of only 14 arc seconds, and cruddy seeing of 3/5 on Feb 9, 2011, there was slim chance my ten inch scope would be able to resolve them individually – although there might be some overexposure here. However, this is good enough to show that collimation held solid! You may have heard collimation on these scopes is sensitive, but this just doesn’t match my experience yet.
This image of Mizar and Alcor is only 3x 30s exposures, and gently processed. However, imaging at the full 2000mm of the AT10RCF is a bit of a challenge for my Starshoot Pro v2 CCD. With a pixel size running over 7 microns, this requires the very best sky conditions to really take advantage of imaging at full resolution. Also worth noting here are the diffraction spikes, caused by the spider which holds the secondary mirror on the scope. Personally, I think they make stars look much more exciting, despite the loss of contrast on bigger, closer objects, like planets.
As I mentioned earlier, this time of year is great for imaging galaxies. So what better to do than pick a few and see what we can eek out? The first target was M51, the Whirlpool Galaxy. Big, bright, and relatively close by, this is one of the few galaxies that you can see some spiral structure on with an eyepiece (mag 8.4, 11×7 arc mins, 23M light years distant) NGC 5195 is the smaller galaxy which appears to be in process of being sucked into M51. Just imagine what it would look like in the nighttime sky to look up with another galaxy interacting with the galaxy you were in!
This image also was binned at 2×2 to bring it a bit more down to size, and is built from 8x 300s exposures. It looks like some additional time would be useful here; if we get another great night I’ll have to take a shot with 10/15/20 minute exposures.
Back to Ursa Major for M108. M108 reminds me a lot of M82, an edge on spiral galaxy with an unusual appearance. This galaxy is about 9×2 arc minutes and magnitude 10.7, making it a generally easy target. Autoguiding here was done through the Orion ED80, and there appears to be a bit of issue — I took some of the exposures up to 20 minutes to see how far I could push it. However, as the exposure times go up, the chance that some small perturbation will cause you to lose the whole sub goes up. In this case, I combined a few 20 minute, 10 minute and 5 minute exposures together – totaling 80 minutes light frame total.
Lastly, there are not a lot of globular clusters out in my section of visible sky. However, Messier 3 is a great looking one which happened to be up right as I was getting ready to break down my scope setup for the night. This is a mere 6 minutes – 3x120s exposures and gently processed in nebulosity. No 2×2 binning here; this is the full resolution that the scope gives (minus my cropping). Overall a wonderful globular cluster in both the eyepiece and the camera.