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    SGL 2017 SP


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About GreatAttractor

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  1. AR12674 in H-alpha and white light (great seeing)

    Great images, and the animation is a killer!
  2. August 21, 2017: First eclipse results

    Great shots! I was wondering what I'd try to image during a total eclipse, and after seeing this and other images I know now it would be a HDR corona. Do you have enough data to attempt a corona time-lapse? Perhaps some movement close to the disc would be visible over these few minutes.
  3. Sun HA 15.8.17 (+ Frankenscope Test!)

    Yes, a very good demonstration there. It's definitely possible, however, the usable field of view will be smaller than with f/7. The linear size of sweet-spot stays the same (so it covers the same portion of your camera's sensor), but (due to the longer f.l.) the image now has larger scale (i.e. less arc sec/pixel); if at f/7 a solar feature encompassed n pixels, now it's 10/7·n = 1.42·n pix. Aperture stays the same, so the level of details visible is the same (they're just bigger). In effect, it's best to stay as close to f/7 as possible. On the other hand, using a smaller F-number would clip the incoming light cone and reduce the effective aperture.
  4. AR12670 in h-alpha (mosaic and 10 min timelapse)

    Excellent details in the animation, including penumbral waves. Let's hope for some spectacular activity next time!
  5. Thinking about a Frankenscope...

    F/7 is recommended. If you couple it with an objective with larger F-number, the linear size of sweet-spot will be smaller (and if you use a Barlow to stretch it to cover your camera's FOV, you'll be likely oversampling). If you use an objective with smaller F-number, the incoming light cone will be clipped (and with it the effective aperture). I use a 90/660 (so f/7.33) achromat in my mod. It is absolutely worthwhile, just keep in mind the trade-offs. Unlike a Lunt 80 etc., a Lunt 50 with larger objective will have a limited sweet-spot; you won't be able to view/image the whole disk at once. For small FOV high-resolution imaging (say, a 1/3" sensor) it's fine.
  6. How can I reduce glare from my monitor when solar imaging?

    Yep, you'll need a head cloth to get rid of reflections. BTW, to me the introduction of glossy screens always looked like a fad ("improved clarity and vibrance" and all that). Fortunately, laptop vendors still have matte-screen models and that's always my key requirement when buying a new one.
  7. Oh, come on, most of us here have :> There's plenty on Astrobin (see e.g. http://www.astrobin.com/users/GreatAttractor/collections/131/) and elsewhere. It's just that once you transition to Hα, it's hard to go back. As for your overexposure issues, it could be due to the ND filter being too bright; at the same time, an f/6 refractor gives a very bright image at prime focus. Possible solutions: - use the Baader ND5 film over the objective lens instead of the wedge (very cheap, practically the same image quality) - add a Barlow - add another 1,25" ND filter (like 25% or even darker; they're cheap too) - add a green filter ("visual" or the Baader Solar Continuum); not only reduces brightness, but improves granulation contrast Combinations of the above will also work. Not recommended, as image resolution is proportional to aperture. The only reason for using a mask would be bad seeing (too bad for full 123 mm), and for white light I'd suggest keeping it at at least 80 mm.
  8. 74 frame animation of new AR 15th June

    Milky haze or not, that's some beautiful activity there!
  9. Kernel 4.10.5 boot problem with Radeon R7 370

    That's right, Mesa.
  10. Lunar sunrise time-lapse

    Thanks, guys. Ultimately, I'd love to be able to do this with my 300 mm Newt, but I guess it'll have to wait until autumn.
  11. Lunar sunrise time-lapse

    Last Friday I finally got around to doing a Moon time-lapse. I wasn't sure what good the small Mak would be, but changes are indeed visible: SW Mak 127, PGR Chameleon 3 mono (ICX445) with Barlow in the nosepiece (~1.6x), Baader red 610 nm filter, around 2-minute intervals, ~4 h total from 7:15 PM local time. The sky was of course quite bright in the beginning, so frames' brightness has been normalized in ImPPG. Too bad the seeing was steadily deteriorating.
  12. Stackistry version 0.3.0

    It's only for solar/lunar/planetary videos, not deep sky as DSS.
  13. Lots of minor activity in AR 2661 (animations)

    Thanks, everyone.
  14. Stackistry version 0.3.0

    New version 0.3.0 can be downloaded from https://github.com/GreatAttractor/stackistry/releases New features: Better AVI support via libav Bug fixes: Fixed crashes during triangulation
  15. I've had a fruitful weekend: good seeing (for 90 mm aperture, that is), crystal clear skies on Friday, and equally good seeing on Saturday with 1/3 cloud cover miraculously sweeping sideways from my location since morning to 4 pm. Too bad I caught only one stronger C-class flare in AR 2661 in all those hours. Everything captured with a 90 mm refractor with Lunt 50 etalon, PGR Chameleon 3 mono (ICX445), processed with Stackistry and ImPPG, showing AR 2661. Overview shot of AR 2661 on Friday morning: Friday, 30-s intervals, 0:53 h and 1:06 h. Lots of small-scale activity, too bad it wasn't exactly on the limb as on Thursday; the spikes and surges would look even better (as in http://astrob.in/262196/B/): Saturday, 30-s intervals, 2:15 h total. A class C2.1 flare peaked at 9:57 UTC (preceded by a few smaller events around): The flare maximum: And the whole material from Saturday on fast forward (5-minute intervals, 4:45 h total), showing the changing aspect as the Sun rotates: