M51 - Spiral Galaxy in Canes Venatici

[Bill Mattil]

All,

I'm still trying to get a handle on using a new AO8, and getting a cloud free sky to test from. But here is an image of M51 taken from my backyard observatory under really atrocious skies.

33x300s 253mm RCOS Ritchey Chretien @ 2291mm - ST10XME/AO8/CFW10 on the AP1200. Driven by, naturally, ACP. This was also the debut image taken with Maxim V5. The guidestar used was mag 11 (gotta love 2290mm of focal length ) and was guided at 1.2 Hz.

Comments welcomed.

PS: For all my whining about having to take new calibration files for ACP<->Maxim V5 at binning 4 it really wasn't that big a deal .

Regards

Bill

[Dick Berg]

Boy, this is perfect guiding!! And the ST10 has a big enough area to capture the whole thing. It's really a pretty sight. A little more time, or different processing, perhaps, and you will be right up there with this: http://www.cosmotography.com/images/...005cs-m51.html

Outstanding!

[Jim McMillan]

Hi Bill,

Lots of detail in the bright areas. You seem to have your AO8 working quite well. At 1.2 Hz - and I'm reading that as meaning 1.2 corrections per second - you're not really able to "chase the seeing" since it's not guiding very fast. But, it does show that the AOx's are really much more accurate than trying to juggle 100 lbs. of mount/OTA a few microns every second or so via conventional guiding!

I find I need a minimum of 6 hrs. of luminance exposure to get much of the faint extended galaxy. Occassionally, I'll go 12 or more hrs. Perhaps some additional exposure would add to this already fine image.

Jim

[Bill Mattil]

Hi Dick,Jim,

Thanks for the comments. And Jim I think you hit the nail on the head. Initial testing that I have done tends to indicate that even with extended guidestar exposures which should remove some of the advantages of an AO unit, the guiding still seems to be better. On the sub exposures I gathered for this image the general corrections were on the order of .1 to .2 pixel as opposed to ~.5 to .6 when guided conventionally. So I came to the same conclusion Jim, that for the most part - moving the adaptive unit is quicker and easier than moving the mass of the telescope.

As for time, sigh, of course you both are correct. More time would help. Or darker skies. The darker skies allow for a much stronger stretch which reveals the faint outer arms better without revealing the gradients that are present from my backyard.

One other note ... calibrating the AO seems to be much quicker than calibrating the mount.

Best Regards

Bill