M16 in S2/Ha/O3: 12hrs from AP180/ML8300

Comment

Comment by Trevor Woodrow on August 11, 2011 at 11:13pm

Incredible work as always Mr. Crisp!

Comment by Philip A Cruden on August 11, 2011 at 8:20am

Wow Richard, stunning

Comment by Richard Crisp on August 10, 2011 at 6:09pm

Exposure details
10 x 15 minutes for Hydrogen
14 x 15 minutes for Oxygen
15 x 15 minutes for Sulfur

total was 39 x 15 minutes rather than the 48 I thought :-(

So it was a total of 9 hours 45 minutes instead of 12 hours

Comment by Richard Crisp on August 10, 2011 at 4:11pm

Conor, thanks

I used my Custom Scientific 4.5nm set for this image

I need to count subframes this evening to say with precision but normally for this object I'd shoot 6 Ha, 20 to 30 S2 and something in the same range for O3

maybe 6 x Ha x 15 min
22 x S2 x 15 min and
20 x O3 x 15 min


that would be 48

When processing I use a pretty strong curve adjustment on the Ha to make the image NOT GREEN and then boost the S2 and O3 curves quite a bit.

The guiding issues caused some of the stars to be fatter than I like so I used a bit of unsharp mask on this one. Normally I avoid sharpening and use only levels and curves and DDP (without sharpening!) but this time I did a small amount of Unsharp Mask: about 30% with a radius of 2 pixels and a threshold of 1

Comment by Conor on August 10, 2011 at 3:33pm

That is an absolutely outstanding shot, Richard. The detail is amazing - Any hallmarks
of a guiding problem are not apparent at all to my amateur eye. Truly inspiring stuff.

How did you subdivide your exposures between filters? (If at all) I expect they were all
3nm filters?

Comment by Richard Crisp on August 10, 2011 at 3:12pm

hey thanks for the nice comments guys. I appreciate them.

On the sleeping/nervous thing: in the Sierra in northern Cal, we never get rain "out of nowhere" so that simply isn't a risk factor. At my ranch, I am not concerned about some bum coming into my backyard and swiping my gear.... We are at the end of a road and are on 185 acres and have dogs that love to bark at the most trivial of things.

The biggest risk is probably the horses that my wife sometimes lets wander around: they are big, strong, curious and stupid....

And we sometimes have the cattle running around near my setup (when we need the grass "mowed")... they could cause damage if they wanted to but they all seem to leave the telescopes alone: there's nothing there for them to eat and they are primarily food-motivated it seems....

Of course one of the horses did take a bite out of the seat of my Quad one time a few years back for reasons we have never quite understood.....

Comment by Marc Basti on August 10, 2011 at 1:49pm

Another nice pic, detail is great. That's funny "sleeping" I'd be too much of a nervous nell to even think about bed. Marc

Comment by spike77 on August 10, 2011 at 11:51am

dude that is sweet gradeA

Comment by Richard Crisp on August 10, 2011 at 9:28am

Hey thanks Mark. I very nearly didn't post it... when I did the initial processing I didn't like the result. This morning I was less tired and took another crack at adjusting the curves and levels and was able to more or less salvage something useful from the data.

I really wish I had discovered that guiding issue on Friday night. That is one of the hazards of unattended imaging.... things can go wrong all night and I don't know because I am sleeping!