PGC 48896 & 11 others

[rogerg (Roger)]

G'day all,

Another PGC FOV. Only down to Mag 18.0 this time, nothing fainter listed in TheSky for the area.

Not as nice this time, had a gusty breeze on and off, mixed with periods of still air and dew requiring me to use the dew tube which acts as a nice sail in the breeze.

I was aiming for (and had scripted) 4 FOV's, but after the second the autoguider failed because of the gusty wind, so it gave up. Oh well.

http://www.rogergroom.com/rogergroom...m.jsp?Item=285

Now I'm really wishing I had an AO7, I'd like to see what that'd do for the sharpness of these 0.88 arcsec/pixel images

Roger.

[astroboy]

Great Deepfield Roger
I don't know if the AO7 will solve much for galaxy shots, I think you need fairly bright guide stars for them and there never seem to be any near faint galaxies.
I was thinking of buying an AO7 for the 12" SCT but now thinking of just buying a better mount rather than making things more compicated than they already are.

Zane

[rogerg (Roger)]

Originally Posted by astroboy

Great Deepfield Roger
I don't know if the AO7 will solve much for galaxy shots, I think you need fairly bright guide stars for them and there never seem to be any near faint galaxies.
I was thinking of buying an AO7 for the 12" SCT but now thinking of just buying a better mount rather than making things more compicated than they already are.

Zane

Interesting..I have to admit I hadn't looked in to exactly how they work. If they need a bright star then that makes it completely useless to me - as you suspected I rarely have a bright star in FOV. Guide exposures are usually about 4 seconds.

The other thing that makes me wonder: If I do have the oportunity to take my guide exposures below 0.5 seconds I notice a huge improvement in quality of image anyway, it appears that at that point it starts to be fast enough to correct for atmospherics. So I wonder how much the AO7 would actually improve upon that, if I'm going to need a 0.5 sec (or similar) exposure time for it anyway. Interesting.

I suppose the other alternative to a new mount (thinking of ways to improve clarity) would be a guide scope, so the guider could be positioned on a bright star not necessarily very close by. But 2 problems with that I guess - 1) positioning the guidescope to find that bright star and 2) having a guidescope with a long enough focal length to match the 2160mm I'm imaging at.

Hmm.

Anyway, I have no money for any of the above options so will continue battling on as is for now

It's good fun doing this faint stuff that no one else bothers to image.

Roger.

[PhotonCollector (Paul)]

Hi Roger,

another nice deep deep sky image. Congrats.

At a quick look with STAR Atlas-PRO the faintest objects are easily Magnitude 19 !

I marked one of them with an arrow in the attached image, the object is GSC2 S232231311602 at J. Mag. 19.03.

I've also attached a screen shot from STAR Atlas PRO that shows the area you imaged.

Your images remind me of those I did when I was using my Cookbook CCD on my 8" telescope.
Like these ones
NGC253 http://www.skylab.com.au/pmsa/NGC253_4.html
NGC4945 http://www.skylab.com.au/pmsa/ngc4945.html
NGC6744 http://www.skylab.com.au/pmsa/ngc6744.html

Cheers.

Paul M

[rogerg (Roger)]

Paul,

Thanks for that. Mag 19 is pretty good. To be honest I wish I was reaching 20+ at 10 minutes of exposure, but I shouldn't get too picky. It's all a big game of numbers... decrease the resolution and increase the focal ratio... decrease the image size (bin 2x2) and increase the captured magnitudes...

Those images of yours from the cookbook are good, I had no idea a cookbook camera could produce such nice images. It's been a long time since I saw images from one of them. I'm not sure I could beat those images now with my SBIG!

Interesting too that the cookbook was a non-ABG camera like my ST7 too, must have helped you a lot with the sensitivity.

I'd like to improve the clarity/sharpness of my images and reduce noise and other problems. I don't feel I've ever improved much in that respect with the ST7 images. Film and DSLR shots I don't have a problem, but I perhaps tend to try and push the ST7 images too far, hilighting the problems in them more. Keen to get more exposure detail to improve SNR.

Roger.