It pays to use the right darks...NGC 6744

[kinetic (Steve)]

I did this set 2 nights ago while also getting RGB data on NGC5128.
That RGB set was 7.5 sec subs cooled to 10C (with 7.5sec darks)
This NGC 6744 set was only 5 sec subs at 10C.
I forgot to do the 5 sec darks for this set and processed this morning
oblivious to the fact that it needed 5 sec darks at 10C.

The first result is using the wrong darks (7.5s 10c darks on a 5sec 10c set)
The second result is with a set of 5sec darks at 10c from a 28th of March
session.

The second one has no trace of the gradients and herringbone noise and
survived a bit of sharpening.


Steve

[DavidU (Dave)]

Amazing difference. I wouldn't have thought the different subs made such a difference.

[kinetic (Steve)]

Neither did I Dave!!!
It has given me much to ponder....
If wrong darks made this much difference then maybe darks wrong by even
half a degree might affect the noise floor too.
My cooling cut in/out cycle has a delta of 2 degrees.
When I stack the darks I can see it fluctuate brighter and darker as it stacks
100s of dark subs.
This seems to even out though because the lights cycle by this 2 degree delta as well.
I'd be guessing that if I chose only the lights that were 10C (and not 11C) and calibrated using only 10C darks (instead of the 11c darks) the result
might be even more surprising.

Steve