First M51

[R26 oldtimer]

I have been wetting my feet at this thing of the devil called A.P. I had a go at M51 during full moon, but before the terminator made its appearance from the horizon. Data was captured during two nights, so the FOV wasn't a  good match.

What puzzles me is stacking in DSS. I have tried with the default settings, custom rectangle, drizzle and no drizzle, superpixel. Stacked 95% of 175, 30s subs along with 30 darks.

DSS came up with several outcomes, drizzle seems pointless, and unless I apply the destroying "dust and scraches" filter on the background, the noise is very high.

So I would very much appreciate any advice on stacking settings, and also would like you to give your best shot at processing this data, as this will give me an idea of how far this can be pushed by more experienced AP'ers.

I've used a bresser 150/750 newt, AZEQ5, Canon 600d, stacked with dss (except for one with sequator), and PS for processing.

My results are here....

And the stacks from dss here....

SEQSTACK.tif

Autosave004.tif

Autosave003.tif

 

 

[happy-kat]

I'll have a play tomorrow I think. Was the ISO all the same and did you check the registration and select your best frame as the reference frame and get rid of any poor frames?

[R26 oldtimer]

Yes, ISO was set at 1600, and no I had no idea of reference frame. Also I didn't reject any subs as there weren't any extremely worst than the others such as long trailing or sat/plane passes. About 1/4 of them had the worst LP, should I had rejected them?

[happy-kat]

Look at the scores and star counts. If they are widely under the best I'd consider removing them. 

[R26 oldtimer]

The star count looked ok, it was about 90-110 at 7% threshold. Ill check the scores next time.

I should also mention that I used artificial flats during processing

[happy-kat]

It is a column visible on the list of frames in the file list. I've found to improve an image need to review the list after registering and before stacking.

[R26 oldtimer]

Taking your advice, I will try a new stack.

Before, I had 182 subs with:

score ranging from 190-740, FWHM from 3.58-5.00 and sky background from 1.86%-4.77.

Now I checked all subs with score above 450, leaving me with 145 subs with:

score ranging from 456-740, FWHM from 3.58-4.56 and sky background from 1.86%-4.69. Also checked as reference frame the one with the highest score.

I am currently stacking the best 95% of them with kappa-sigma 2/5, no background calibration, no RGB align.

I will post the outcome ASAP!

[happy-kat]

That's great. If your telescope is left focused as it was with camera attached the same way you could perhaps rattle off some calibration frames too.

[R26 oldtimer]

That would be nice, but I've left the newt at my summer house, so I don't have it with me. At least I managed those 30 dark subs!

[R26 oldtimer]

Here is the stacked image:

Autosave006.tif

[R26 oldtimer]

Hahaha, just tried to process the above stack and this stacking artifact appeared:

Is there any Scottish whiskey called galaxy? Might sell them the photo for advertisment!!

[R26 oldtimer]

Here is a better stack, sorry everyone!

Autosave007.tif

and here is how I've processed it, I'm sure you can do better than that.