NGC6820/23 slow cooked*re-done with darks ect*

[MikeD]

I shot 5 x 30 min subs to add to the 10 x 10 Min's I already had.

Worth the extra effort to get the noise down, although I may just go for another 15 @ 10 Min's rather than 5 @ 30 Min's next time to keep the image tighter.

No darks or flats applied to the new image yet, as the darks are still being collected.

(10@10 mins+5@30mins )

(Previous image 10 @ 10 mins)

Mike

[Jamie]

The difference is very apparent mate..

Nice one...

[geppetto]

Yes, worth the etra subs 8)

[MikeD]

Thanks guys.

I have had a chance to redo the processing with Dark, flat and bias frames.

(click to enlarge)

[centroid]

When both of the first two images are 'pulled up'on screen, side-by-side, the reduction in 'noise' is very apparent. Nice work Mike.

BTW, what's causing the 'halo' around the larger stars?

Dave

[MikeD]

The thoughts on UKAI are that it could be reflection between the ha filter and the ccd coverslip.

I will be looking into it ASAP.

Mike.

[CELESCOPE]

nice one Mike .nailed it this time i reckon , and yes be nice to rid those halo,s but otherwise a great deep image

Rog

[centroid]

The thoughts on UKAI are that it could be reflection between the ha filter and the ccd coverslip.

I will be looking into it ASAP.

Mike.

Sounds logical Mike.

It will be interesting to hear what you find.

Dave

[MartinB]

That's exposure time for you! Nice work Mike. How are you combining the different length subs?

[MikeD]

Just as normal 15 frames stigma clip combined in maxim.

[MartinB]

Will this mean that the average pixel level corresponds roughly to a 15 min exposure and that potentially accurate pixel values are being lobbed because they are a long way from the mean? I've been wondering about the best way to combine subs of different lengths. I saw a thread on the newccdastro yahoo group in which Ron W suggested combining each of the 2 sets of subs in the usual way and then combining these 2 stacked images using a sum combine. I've never really had to try it but wonder whether it would make any difference.