My best ever NGC253 and a better Grus galaxy group

[tornado33]

Hi all
Was up till 4:30 am imaging last night, temperature was comfortable, sky clear albeit hazy, seemdd quite light, but was stoked to get the best ever NGC253 pic Ive taken, a full hour on it. I started when it was right at the zenith. 6x10 mins ISO 200

I also re-imagged the Grus galaxy grouping Id done previously, this time fitting in all 4 of them, including NGC 7552 at lower right
4x10 mins ISO 200
Darks, flats, offsets processed as usual in IRIS, adjusting dynamic and colour stretching to get the faint outer details while not over exposing the inner bright parts, then finishing off in Photoshop.

Digital SLR's never cease to amaze me, the sky was so light that I could barely see the LMC even at 4 am when it was near its highest, yet can pick up the galaxy detail it has :)
Both images shot with 10 inch f5.6, off axis hand guided (gee it was a long session lol),IDAS uv/ir filter and MPCC used, on modded 350D. Some light to mod. gusts of wind but as it was coming from the NW I was protected by trees and the house and fence, VERY dry, no dew at all. If Id had Strikers cooled camera I could have wound the cooler to full without condensation :)

Larger images here
http://www.users.on.net/~josiah/mod350d/ngc253%206x10mins%20iso200.jpg
http://www.users.on.net/~josiah/mod350d/ngc7582%20whole%204%205x10minsiso40 0c_filtered.jpg
Scott

[iceman]

Both stunning shots, Scott! I love the Grus cluster!

I hope the transparency is better at Kulnura tonight!

[Adrian-H]

i like the one with several galaxies, you can out afew smaller ones in there too very nice

[EzyStyles]

stunner! both shots are very nice and smooth. Can i ask why ISO 200 and not ISO 800?

[RB]

Stunners Scott !

:eyepop:

Amazing results despite the conditions you had.
Well done.

[astroboy]

Great shots Scott
Nice colour in the NGC253 and some good detail in the cluster:thumbsup:

[Garyh]

Great shots Scott, I agree with Zane ngc253 is just the right color balance to my eye!..:thumbsup:.. Grus cluster is a beaut as well..
Too hazy up here last night and the stars were dancing all over the place..lol
Cheers Gary

[Lee]

fantastic images Scott - love the quartet......

[tornado33]

Thanks all. Kulnura is heaps darker then here :)
Eric, I used ISO 200 as ISO 800 will only allow 2 or 3 minute exposures before fogging out, and Im comfortable doing 10 minute shots so use ISO 200. I wont ever use ISO 100 though as I read that it compresses the dynamic range, whereas ISO 200 pretty much reads the data straight off the sensor. If I had skies like Kulnura or darker Id definately try ISO 800.
Shooting ISO 200 also sees that the bright cores of the galaxies wont over expose.
Scott

[beren]

Geez thats great :)

[andrew]

Wow I love these images, fantastic, especially the second one, you can actually get a feel for the depth of our universe :)

[strongmanmike]

Both very nice images Scott, very well done :thumbsup:
You are a bloody trooper mate with that manual guiding :eyepop:

Interestingly though, your DSLR with the 10" Newtonian gives about the same FOV as my much smaller SXV-H9 with my 80ED and surprisingly about the same resolution too, even though it is over twice the focal length.

http://www.pbase.com/strongmanmike2002/image/57083059/original

http://www.pbase.com/strongmanmike2002/image/62750035/original

I think this is testement to the benifits of a monochrome CCD over a bayer matrix one shot colour CMOS, particularly as far as resolution goes. A small pixel mono CCD camera on an 80mm F7.5 (600mm FL) refractor produces about the same resolution as a DSLR on a 254mm F5.6 (1400mm FL) Newtonian - interesting huh?

Mike

[tornado33]

Howdy all.
Yes the camera can sure see much deeper then a human eye at the scope can see.
Thanks,Mike, yes your shots are almost exactly the same scale as mine:) heres the sensor info for my camera
its 3474 x 2314 pixels
Pixel size: 6.4 µm
I note yours has a similar pixel size
In theory monochrome sensor should have roughly 3x the resolution I guess as all the pixels are "seeing" the light or a certain colour, whereas in a colour sensor only 1/3 of them see a particular colour.
What Id do if I was running Canon is make their sensors in a monochrome model too (should be even cheaper) then put it in a thermoelectric cooled body and sell it as an astro camera or to astro camera makers
This info from Terry Lovejoy's site

http://www.pbase.com/terrylovejoy/dark_noise__a_closer_look
Noise in 900 sec exposure @ 31C = 34 e- RMS, dark current = 0.5 pAcm2
Noise in 900 sec exposure @ 6 C = 6 e- RMS, dark current ~ 0.01 pAcm2
For comparision STL-11000M has claimed dark current of 0.1 pAcm2 @ 0 C
Thanks
Scott
PS, An autoguider would be good but my mount has only a RA drive and the drive corrector hasnt got facility for autoguider input.