Ngc 6397

[codemonkey (Lee)]

I don't usually shoot globs, but I have a new camera and clear skies and a choice between using a flattener, or guiding. Curvature without the flattener is about 44%, which is nasty, so I decided shoot some 5s unguided subs.

Only about 30mins of data, though I was imaging for 2.5hrs on this -- partly because the huge amount of overhead with short subs, partly because I discarded a fair amount.

This is uncalibrated -- no darks, flats or bias.

Larger version is available on astrobin.

[strongmanmike (Michael)]

Lovely result Lee but by the look of it...I think you mean NGC 6397 (Ara)..? Reminds us that bare bones quick imaging can still produce a very satisfying result

lets hope with advances in imaging technology over the next decade we get to a point where 30min+ exposures for 40hrs have become just a crazy habit of the distant past that we chuckle about....like E.E Barnards 12hr marathon hand guided emulsion plate efforts of over 100 years ago

Mike

[codemonkey (Lee)]

Absolutely right, Mike, I did mean 6397. Don't know where I got 6370 from. Thanks for the correction.

It will be very interesting to see where the future takes us. There's already a few using big, fast scopes and very short sub lengths, but I don't find it practical just yet.

I for one look forward to getting back to my normal sub lengths (and non-glob targets hah).

[Atmos (Colin)]

For 5s subs it's turned out quite well, didn't think you'd have thrown away data with only 5s subs though.

[codemonkey (Lee)]

Originally Posted by Atmos

For 5s subs it's turned out quite well, didn't think you'd have thrown away data with only 5s subs though.

Cheers Colin. FWHM ranged from 1.7 to 6. I ditched anything 3+. Last I was guiding I was having some 4-6" spikes in RA, so if one of those occurred within a 5s sub, it'll be ruined.

[RickS (Rick)]

A good result, Lee.

[gregbradley]

Nice image Lee. Looks like you are getting a handle on this new ASI1600 camera.

What gain did you use here?

Greg.

[atalas]

Lee quite a beautiful shot!I've always enjoyed globs,visual or imaged

I think the contrast looks very good,well resolved,the little thing I would be concerned about would be the pink stars.

[Placidus (Mike and Trish)]

A nice rendition, Lee.

Shows how for a really intensely bright object (moon, bright open or globular cluster), very short subs work just fine.

[codemonkey (Lee)]

Originally Posted by RickS

A good result, Lee.

Thanks Rick :-)

Originally Posted by gregbradley

Nice image Lee. Looks like you are getting a handle on this new ASI1600 camera.

What gain did you use here?

Greg.

Thanks Greg! I used unity gain here. At this point I'm thinking to mostly shoot using unity and relatively short (but not this short!) subs to reduce read noise and quantisation issues. I'll experiment a bit once I can start guiding again to find a decent sub length.

Originally Posted by atalas

Lee quite a beautiful shot!I've always enjoyed globs,visual or imaged

I think the contrast looks very good,well resolved,the little thing I would be concerned about would be the pink stars.

Thanks mate :-) The stars do look a little pink, you're right. Appreciate the feedback.

Originally Posted by Placidus

A nice rendition, Lee.

Shows how for a really intensely bright object (moon, bright open or globular cluster), very short subs work just fine.

Cheers Mike. While the short subs can produce ok results on bright targets, they really are a PITA to process. Not something I plan to keep doing.