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vlaiv last won the day on June 3

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About vlaiv

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  1. Why do you think that is? What about over sampled images do you find easier to process?
  2. Both, as they both have the same resolution (unless you drizzle for some strange reason) in both sampling rate and captured detail. Yes, that is correct formula and if I understand correctly - you were using camera with 3.72µm pixel size and 420mm of focal length, right? That gives sampling rate of 1.83"/px - that is correct. This, however, does not mean that you'll be properly sampling the image - or in another words, although on paper 1.83"/px sounds ok in principle - it is not always ok. In order to properly sample with 1.83"/px - stars in your image need to have FWHM of a
  3. When comparing large and small instrument - following applies: 1. if you set your target sampling rate - say 1.1"/px, then something like 5" refractor will be x4 as slow as 10" RC. Once resolution is set - aperture tells you how fast system is. More aperture - faster the system, simple as that (in fact speed increase is ratio of aperture surfaces - and even large CO in 10" reduces surface by very small amount). 2. In same seeing and with same mount performance - larger instrument will out resolve smaller one. Just by how much - depends on many factors (or rather relation of
  4. Actual resolution of the image will depend on seeing conditions combined with scope aperture and mount performance. This means that it will not be the same each night. In fact - it won't be the same between subs. Stacking averages sub to sub difference so you can look at final stack to estimate actual resolution of the image. Take average FWHM of stars in your image in arc seconds and divide that with 1.6 to get good sampling rate for such image. You can also see if image is oversampled if you just take a look at it at 100% zoom. Here is part of your image: Smallest stars
  5. I like the idea of pushing the data only to the point it will let you. As soon as you push it beyond that point - it will start to show. Noise issues will become apparent, and so will some artifacts in the image. Second image in my view is much better at this - it is not nearly pushed too far as first image. In fact it only shows traces of noise and that is because it is a bit over sampled. If it were binned to proper sampling rate and stretched like that - it would not show any noise (and in fact - it does not show it when viewed at say 25% zoom).
  6. I think it would do a good job as 4" all around visual instrument. Maybe not the best at high power / planetary, but otherwise better than your average 4" achromat. If you want very good high power views as well - there is version with FPL-53 glass, but it costs about 80% more. https://www.teleskop-express.de/shop/product_info.php/info/p9868_TS-Optics-Doublet-SD-Apo-102-mm-f-7---FPL53---Lanthan-Objective.html (again, availability is issue - all gear seems to be affected to some extent) In my view, even version with FPL-53 is not really suited for OSC. You can use it with spec
  7. It is probably same as this (and number of other scopes branded differently): https://www.teleskop-express.de/shop/product_info.php/info/p4964_TS-Optics-ED-102-mm-f-7-Refractor-Telescope-with-2-5--R-P-focuser.html It is FPL51 doublet, has some residual color (very small amount by all accounts) and is very good visual instrument. I know I would like one instead of regular 4" achromat - either short one at F/5 or long one at F/10 - it will give better image than both.
  8. It is reasonable to take color subs at bin x2 in comparison to luminance - maybe even x3. I'm not really sure it is reasonable to take images at 2.3µm pixel size though. Maybe with 60mm F/4 scope - but anything more than that and that pixel size in itself is not reasonable. This is because it gives too high sampling rate. With 60mm F/4 scope - it will give 2"/px and that is ok for such small scope - maybe even that is oversampling. Say you want to it with Esprit 100mm that is F/5.5 - That will already give you 0.87"/px and that is not achievable in regular seeing conditions with even
  9. I would recommend the following workflow to best match color / mono data from two different sources: 1. capture mono at resolution you want to work with (best to keep things above 1"/px if you can as there is not much point going higher res than that) 2. capture osc data at any resolution (again, use reducers or what not to get to reasonable sampling rate - but if you can't - you'll fix that later) 3. Stack mono data 4. Stack OSC data using super pixel mode or split debayer mode 5. Bin OSC data to first suitable resolution lower than mono data Say you captured mon
  10. You can do both. You can bin OSC sensor to produce mono data, and you can bin it in special way so that it is binned x2 and still produces color data. Both of these are "sub optimal" - or rather don't quite do as you would expect from software binning / SNR point of view. First - producing mono data. You can bin Bayer matrix data and you will get mono data - but it won't be the data as produced by mono sensor for couple of reasons. - bayer filters loose a bit of QE (like any filter does - even in part where they pass light). Compare mono vs osc QE for same sensor:
  11. I'd say that is an understatement https://en.wikipedia.org/wiki/Cosmological_constant_problem
  12. Yes, at those distances, but not under the apple tree
  13. Anything we conclude is only a possibility not a fact. You could say that things falling in gravity is a fact, but I'll tell you that that has been our experience so far - but we can't really state that as a fact - as it can change at any moment. Only thing that you can say is that: Within your experience it has been so. Was it so 10000 years ago? We can easily say that it is very very very likely that it was so - but we don't know that for a fact. This should not bother you though as any scientific theory can fall at any moment - and when it does, we will work to create better one -
  14. That really depends on curvature of universe. If curvature is zero or negative - we have infinite universe. If curvature is positive we can have closed universe with finite spatial extent. In some special cases, zero curvature can also mean closed universe - but that requires non isotropic universe and cosmological principle states that universe is both isotropic and homogeneous on large scales. Currently measured value of curvature is very close to 0. It is actually 0 with some margin of error (0.1% or so) - so we can't really tell if it's zero or just very small within measure
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