M101 - 1st LRGB attempt

[Kbramley]

My first real go at LRGB, had a nice clear night and 4 hours spare on Saturday. M101 was nice and high so decided to give it a go.

MN190 & 383L+

OAG and modded webcam

20x300s L

6x300s R

6x300s G

6x300s B

All bin 1x1, Flats,darks and bias applied and stacked in DSS

Had to throw away 8 subs due to satellites which was particularly annoying, seemed worst than normal, I'm guessing it's something to do with imaging directly above?

Processing was tricky and the image has an odd gradient at the bottom left and the star colours are wrong, some burnt out and the colour is a bit too purple I think on the galaxy buuuut but I'm pleased with this one for starters. Needs more RGB subs.

Thanks for looking

Keith

[red dwalf]

i like that, i`m fairly sure dss will get rid of the satellite trails, think sigma kappa clipping helps, shame to throw away subs,

doing M101 myself at the moment but only got 19 x 7 minutes lum subs, hardly stopped rain and being cloudy since

[Kbramley]

Cheers for the advice, I shall try out sigma kappa clipping and see how it goes, currently I have only used the average method for the lights. Most of the trails were very bright however, brighter than the core of the galaxy, also most passed through the galaxy itself . 

Keith

[michael.h.f.wilkinson]

Very nice image. I always love the galaxies scattered round M101, and you have captured quite a few

[Kbramley]

Yeah lots of little galaxies floating about, looking at the Hubble pics of this area its littered with them - oh for more aperture and no atmosphere

[GuillermoBarrancos]

Absolutely fantastic result!  The MN190 suddenly made an entry to my shortlist of possible Scopes.

[r3i]

Fine image, and I always like seeing all the little fuzzies around the main target.

Yes, sigma clipping should allow you to keep the subs with satellite trails.  I was imaging the nearby M63 a few days ago and had quite a few subs with trails and one of them went straight through the core, but the equivalent operation in Nebulosity took care of them.  I think I've only ever had to ditch one sub in the past which had a partcularly strong trail that ended up being visible in the final stack, though I think in that case I didn't have too many subs to begin with.

[Kbramley]

Thanks for the  comments. I have set DSS going on the Lum data with sigma clipping ( with 2 and 5 iterations selected - not sure what's best here),  I included all tracked images including a really bad one, will post up the result when I get chance to add the RGB data

keith

[FranckiM06]

Very nice your image with very good process

[Kbramley]

Wow that Kappa-Sigma clipping is a powerful tool, I threw all the bad tracked out subs in and not a peep on the final Luminance stack, i have shown one of the worse subs below and the resulting stack, and the final LRGB process, I'm a convert , thanks for the tip fellas.

Worst sat track in the subs

stack of 28 using Kappa-Sigma clipping (Kappa 2, Iterations 5), 8 of which contained sats

Final LRGB image, showing no sat tracks

Keith

[red dwalf]

Nice, glad it helped, shame to throw away subs.