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About GreatAttractor

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  1. GreatAttractor

    Rechargeable Battery Recommendations

    Second that. I use a CSB EVX 40 Ah AGM battery, enough for an at least 8-hour session with HEQ5 tracking and lunar/solar/planetary recording (though I don't have dew heaters). HEQ5 is hooked directly to 12 V DC, for the laptop I have a cheap 150 W DC-AC converter.
  2. GreatAttractor

    Solar animation (a first)

    GONG is also useful. It can show a time lapse of the past few hours' activity, so you'll know if something new is happening and it's time to move the scope.
  3. GreatAttractor

    Solar animation (a first)

    Very good result. What telescope did you use?
  4. I've played with raytracing (i.e. geometrical/ray optics only) a bit, indeed it's straightforward. Building a full-fledged optics simulation tool with nice 3D GUI would take a lot of time, though. Still, a simple command-line prog accepting a textual description of optics is enough for some simple experiments (e.g. define point light sources spaced on a grid, “image” them through an overly short-f.r. Cassegrain and make a time lapse out of it around the focal plane, illustrating the distortion and field curvature). Ping me if you decide to go down this route and have trouble with deriving formulas for reflection off paraboloid or hyperboloid...
  5. GreatAttractor

    Solar Imaging Showcase 2017

    Everything shot with 90 mm refractor + Lunt 50 etalon. Smoky prominences (~1 h total): M5.3-class flare on 4/02 (0:46 h total): AR 2661 on fast-forward (5 hours with 5-minute intervals), with a minor C2.1-class flare. Solar rotation clearly visible: 7-pane mosaic:
  6. GreatAttractor

    Lots of minor activity in AR 2661 (animations)

    It's a “mod” which increases the aperture (and resolution) at the cost of reduced sweet-spot size (i.e. whole disk cannot be viewed in Hα). Details: https://solarchatforum.com/viewtopic.php?f=9&t=19238
  7. I believe this only applies to an x86 guest on an x86 host. But virtualizing the Pi is an ARM guest on an x86 host.
  8. GreatAttractor

    First prominence image on relatively new gear

    Good result, Dave. Autostakkert! will handle a drifting image without problems. Regarding the glare - keep a towel (e.g.) on hand and just put it over your head and the box for focusing/etalon tuning. And make sure your next laptop has a matte screen
  9. GreatAttractor

    Chameleon First Light

    Good to know. I'm considering moving up from my Chameleon3 ICX445 to one of those fast CMOS sensors. Keep us posted!
  10. GreatAttractor

    Chameleon First Light

    The first Chameleon was a USB 2.0 ICX445 camera, but these days there is a whole series of "Chameleon3" cameras: https://eu.ptgrey.com/chameleon3-usb3-vision-cameras from 1.3 to 5.0 MPix (that's why I state my sensor when listing the HW used in capture).
  11. GreatAttractor

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

    Great images, and the animation is a killer!
  12. GreatAttractor

    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.
  13. GreatAttractor

    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.
  14. GreatAttractor

    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!
  15. GreatAttractor

    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.

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