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How much more Luminance


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I decided to try a difficult subject (perhaps too difficult), NGC6384 Barred Spiral in Ophiuchus.  Below is 80 min of Luminance using 10 minute subs with appropriate Flats, Darks, bias.  Processed in DSS and PI.  

Meade 12 inch ACF, LX850, Leupus 0.62 reducer, Trius SX-9, Lumicon deep sky light pollution filter, Astronomics Lum filter,   My site is urban, on the Bortle scale ~ 5-5.5.

Would another hour of luminance help to separate the galaxy from the background?

Would another light pollution filter such as the Astronomics CLS be a better choice (the lumicon is the only one I have at this point)

All suggestions appreciate

Mark

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That is not a huge dose of luminance. Using sigma reject there is a big advantage to going for around 12 subs or more. Since the subs are also quite short you'd continue to gain advantage until at least 25 subs.

I'd have a good look at focus, too. The stars look a little large to me. This might be a guiding issue though. Round stars don't prove the guiding is perfect. Random errors also give round stars.

Olly

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Thanks Olly,

I will collect a bunch more lum, before I bother with color

For focus I used a Bahtinov mask, it seemed perfectly centered,  I am not sure if this is the best way or if using FWHM is better?

I am still working on tracking, I use an LX850, did the pec training and guiding calibration, that has improved the visual assessment of tracking, still working on getting the RA and Dec histograms to work.

Makr

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  • 2 weeks later...

Unless your sky is pristine and truly dark there is no point of collecting Lum without the use of an LP filter. The amount of noise also indicates that the data is really short. Use an LP filter, increase the sub length to 900s and collect a minimum of 16~20 with dithering and use as Olly has suggested,  Sigma Clipping to get rid of a lot of the nasties.

A.G

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