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Worked with subframe selector last night and this morning. Vrry easy to work with and quickly identify outliers in my data. Definitely what I was looking for. Blink was utilized to screen for clouds and other issues prior to utilizing subframe. Thanks again everyone for their input. |
4.29
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I follow up any imaging session with a quick review in Blink. First reason is really very subjective. I just like to see what was captured and look at the images first before I start relying on algorithms that give me quality parameters. Second reason is to toss out the obvious errors like mentioned above (trees, clouds, etc). And third reason is that it gives a nice quick Timelapse of what happened throughout the night. Did the dithering work ok, is there any sign of excessive field rotation due to poor PA, etc. The weighting process in WBPP has become very advanced, so if the dataset looks good, I usually go straight into WBPP. If data is collected over many different nights and/or data may look more variable, I would first do a SubFrameSelector run and eliminate eccentricity >5.5/6 and # stars well below the average. |
7.61
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When possible, I image all night, so 2-3 hours at a time unattended between alarms, and the most critical role Blink plays is for when the target has moved off center due to a long enough interruption in guiding (passing clouds) which, if there’s also been a meridian flip, I may not notice the next time I check on things. Anyhow, once guiding has resumed, the subs may look great to subframe selector, but including them in the integration will result ina lot more cropping than I want…. I need to bite the bullet and switch to NINA advanced sequencing with the re-center after drift function, but in this hobby, once hardware, firmware, and software are all working, connecting, and stable, I get very paranoid about changing anything…….. Cheers, Scott |
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While I've only been using PI for over a year-- I usually just use Blink for: a) making sure that overall my frames were 'ok', to remove slurred images b) eliminating any images where it's obvious there were clouds passing thru (I don't worry about satellites) c) that there are no blank frames near the end of the session from nearby buildings I use Subframe Selector to sort out the best frames before I go to WBPP. I use FWHM, Eccentricity, Stars (and sometimes Median) to delete frames that are over 2 sigmas away from the average values in each case. Hope this is helpful. |
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Richard Milford: Absolutely helpful. This was the new workflow for my latest image and felt it really got rid of data that would damper the final image. I focused on FWHM and eccentricity. I honestly don't really understand median too well but if I saw an outlier on the curve I removed it. |
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| Cool....median is basically a measure of light pollution. Initially the values are high at the beginning of a session then they fall has the night progresses and then they rise again towards daybreak. Typically, after I use the first 3 (ie. FWHM, Ecc, and Stars) when I use median the marginal ones are already marked due to the collinearities so I won't use median at all. |
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| @Richard Milford ok cool, I understand now. I was noticing the curve was U or V shaped and this makes total sense. Thank you |
8.59
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I would say, do some personal experimentation. Stack everything, blink and discard only the few worst offenders and stack again, blink and discard a more significant number of offenders and stack again. Compare the results. This is the only true way to know if your procedures are improving results, worsening results, or having no effect. I use blink fairly religiously in my process. However, I look for a multitude of factors, and will often run it with and without the automatic stretch, to determine which subs to discard. More important than background sky levels is the quality of the details...stars, their size, shape...framing (sometimes something happens and framing ends up just wrong), etc. If I see star trailing, or a major frame shift, those are guaranteed discards. When it comes to background sky...its rare that I'll discard one just because its brighter. More often, if I discard a sub due to background sky, its because of extinction issues due to passing clouds. If a sub is lacking detail (or even stars) in a non-trivial portion of the frame due to a cloud), I'll usually discard. It may not matter a lot, but it can matter some, and if there are a number of frames like that it can mess with your details. Simple strait up background sky brightness differences....those would have to be SIGNIFICANT to warrant a discard. I've done a fair amount of testing with and without moonlight in my subs. I've stacked frames that had an additional 200e- signal JUST from a bright full supermoon with normal subs from a new moon night, and in the end I really didn't notice the difference. In the end, if you really want to know what your processing tactics are doing? Test! Test, and figure it out. It can take a little time, but in the end once you know, you KNOW, and from then on you can tune your process accordingly. |
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1000x thanks for your experienced input Jon. Testing takes ALOT of time on my i3 laptop! I'll go off and study some patience now  |
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1000x thanks for your experienced input Jon. Testing takes ALOT of time on my i3 laptop! I'll go off and study some patience now Upload the frames somewhere... I just upgraded my computer and its blazing fast now. I could probably make pretty short work of a few integrations. |
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Jon Rista:1000x thanks for your experienced input Jon. Testing takes ALOT of time on my i3 laptop! I'll go off and study some patience now Wow, that is a kind offer Jon! The next integration run I do with varying sky brightness I will do exactly that and get back to you... I would love to hear your input! |
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| While I don't use the script to process my images, subframe selection is a great tool for identifying anomalies within your data. When running Image Calibration be sure to include pedestals. Cheers |
