M22

[rat156]

From a couple of nights ago.

LRGB 20,10,10,10 minutes.
Skywatcher ED80, SBig ST10XME, AO7.

http://i195.photobucket.com/albums/z...6/M22LRGBo.jpg

Cheers
Stuart

[Rob_K]

Nice shot Stuart. Good contrast, lively colour & real depth. Like the scale too, with lots of starfield context to frame M22.

Cheers -

[iceman (Mike)]

Photobucket seems to be down. I'll come back and take a look later.

[Dietmar]

nice colors, Stuart!
I also like the framing.
it seems focusing might have been difficult - perhaps you face the same situation as i most often do here: turbulances in the air and therefore bad seeing...

[Garyh]

Nice Stuart!!!
Nicely framed and very nice star colors!!
Well done!

[Ric]

A well presented image Stuart.
Very enjoyable to view, everything is quite sharp and there are some nice colours as well.

Cheers

[jase (Jason)]

Nice image Stuart.
I find it intriguing that you're using an AO unit for such a short focal length instrument. With an image scale of 2.33 arcsec/pixel, I'd be interested to know how much benefit it is actually providing. I guess this also depends on your mount PE as well as seeing.

[rat156]

Hi Jase,

I'm using the AO unit as it's bolted to the front of the camera. If I don't use is the mirror oscillates (I think because the fan on the camera is running) and it smears the stars in the corners of the frame. Also the AO7 is basically used to correct for guiding errors, not atmospheric disturbances. I usually use a 1-2 second guiding exposure, which is not fast enough to correct for seeing. Also the seeing has been so crap of late that's all the FL I can use.

I've tried using an f5 and f6.3 focal reducer, but they end up too far away from the CCD and induce coma. I can still use the f5, if I unbolt the AO7 and rely on the mount (LX200GPS), but the focal length ends up pretty much the same (1000mm vs 600mm), both are pretty much widefield. The other problem with the f5 and the st10 chip is that the guide chip and edges of the frame show coma, quite badly.

Cheers
Stuart

[Dr Nick (Nick)]

Very nice colours and contrast!

[jase (Jason)]

Thanks for the explanation Stuart. Have you measured the LX200GPS mount peak to peak PE? As you indicate, the AO is simply masking the mounts flaws to provide you with better guiding. With a tilt tip mirror that can update 40 times a second, its specifically designed to beat the seeing.
I look forward to seeing more of your work.