I made my first ever attempt at M81 on Friday night. Conditions were far from ideal but I'm pleased with the result. I certainly want to try it again from a dark dark site with good seeing. Maybe DSC?
Usual setup: Modified Canon EOS 350D on Celestron C11 with F6.3 focal reducer and CLS filter.
32 x 5min exposures at ISO 800.
Stacked, asinh scaling 2x2 binning in IRIS followed by mild deconvolution.
(http://homepage.ntlworld.com/the_shelleys/Astronomy/bode230109.jpg)
Lovely image Mark, nice to see it in colour. Far be it for me to make comments on other's work that I have not even attempted yet, but is it a bit grainy and what would be the cause of that?
What are the co-ordinates of this galaxy, or what constellation is it in. I am sure I could look it up, but if you happen to know.
Carole
Hi Mark,
What a great start - like you say more subs from a dark site would really improve it. You've processed well holding back on the core. Is this the full FOV? Some of the stars (especially top left) look a little elongated but it's not the same all over the frame so I'm guessing it's field flatness rather than guiding errors? Maybe just a dodgy frame in the stack?
Great shot though & nice to see in colour.
John
Looks ok to me, I ran it through a noise filter etc, probably needs the colour balance sorting.
(http://farm4.static.flickr.com/3131/3225214560_fc08ee99ea_o.jpg)
You did very well Mark, the conditions were quite poor on Friday night.
Carole,
Ursa Major. Graininess (a.k.a. noise) is always present in CCD images. Normally one adjusts brightness levels so that it is very faint and not noticeable. For this particular image, the spiral arms are so faint that in order to see them at all, you see all the noise as well. Unless you have Chris's noise filter!
Chris,
What did you use do do the noise reduction? It has done an excellent job.
John,
The elongated stars towards the edges are due to coma. The reducer/flattener is unable to produce a flat, coma-free image across the whole DSLR CCD (at least, that is, the reducer/flattener I'm using).
I can't wait to try again at a dark site.
Mark
Wonderfull image Mark, you've brought out the outer spiral arms nicely would be interesting to see if you can bring out those Ha regions a little more, Im currently having a go at this myself with some Ha data I got on Friday night myself, haven't quite got the hang of it yet as the data I managed to get wasn't great (as you mentioned, friday was pretty bad, can't believe you managed to get such nice data that night).
Daniel
:O)
Mark,
I used a K-Iterative Noise filter in AIP4WIN to remove the CCD Noise and Poisson noise as well, cool eh.
I'll run it through some decon as well now, I was in a rush this morning, good image bye the way.
Chris
Mark it's the first time I have seen this. I think it is very good with the Canon. Now going to look at your latest one!