Min score value in DSS

[leemanley]

Morning all, I've got 4 and a half hours of widefield Cygnus subs that I'm playing about with, while I've been getting things sorted in DSS I have noticed the 'check above a threshold' tab, so quick question, what is the lowest score that you would recommend to use ?

Thanks, Lee

 

[Steve Ward]

Personally I would inspect each sub up close , reject any with obviously dodgy star shapes or trailing , and then just set DSS to stack 100% of the subs that you feed it ... 

[Knight of Clear Skies]

Good question. I get widely fluctuating scores from night to night, possibly depending on the target, sky brightness, temperature, seeing and how good my focus is. I tend to drop any subs with a significantly lower score than the others rather than at a set value, but I'm not sure if that's the best approach.

[wxsatuser]

From the DSS FAQ

What is the score, and what is its meaning?
The score is a measure of the picture quality.
To put it simply, the higher the score, the more round and not too big stars were found.

[lensman57]

Morning all, I've got 4 and a half hours of widefield Cygnus subs that I'm playing about with, while I've been getting things sorted in DSS I have noticed the 'check above a threshold' tab, so quick question, what is the lowest score that you would recommend to use ?

Thanks, Lee

Hi Lee,

This is only useful if you  have a huge number of subs, then you can pick out the highest scores and use them to stack. If you are talking about a dozen or so subs then it is easier to just sort them visually . From night to night or even hour to hour on the same night the seeing and at times the guiding changes so does the FWHM, the S/N ratio and so on so don't  get too hung up on this.

Regards,

A.G

[leemanley]

Thanks WX and AG, I'm looking at stacking around 140 x 2.30 min subs, I took these seperately last week over a few sssions and I can clearly tell the difference in the seeing as one sessions scores were considerably lower than previous outings, I'll play with 'checking above a threshold' and using the whole lot to see if it makes any drastic changes. 
Thanks Lee

[lensman57]

Thanks WX and AG, I'm looking at stacking around 140 x 2.30 min subs, I took these seperately last week over a few sssions and I can clearly tell the difference in the seeing as one sessions scores were considerably lower than previous outings, I'll play with 'checking above a threshold' and using the whole lot to see if it makes any drastic changes. 

Thanks Lee

Hi Lee,

I normally go fovery long sub length now so I ened up with between 10~15 subs at  best and I usually donget the chance to return to the target again but I have learnt now that sometimes less is more , if the sub S/N is too far away from teh mean I chuck it out as it degrades the stack, with a large number of the subs like your's I'd appilly set the threshold slider to 60% after having thrown the rubbish out.

A.G

[PorkyB]

I usually stack all subs that have a score at least half as good as the best one.  Sometimes that is all of my subs, sometimes just a small proportion.  You can sort the list by score, so it's easy to see the point where the quality drops off.