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brianb

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Everything posted by brianb

  1. Rubbish. Everyone should know that the world is square.
  2. Did you try asking them round ... if they see how much of an issue their lighting is, they might do something about it without being nagged.
  3. Wow! Superb details especially on Plato's floor. Must be getting close to the resolution limit even with 14" ...
  4. Your dad is obviously sensitive to grass pollen but not tree pollen - which is the issue at this time of year. I've been sneezing for the last month, these last few days have been horrid. Grass pollen doesn't affect me anything like as much.
  5. 2011 Apr 22, 1001 UT. FLT 110 @ f/21, Solarscope SF-100 Ha filter set, DMK21
  6. Thanks guys! AR 11195 looks active today (22nd), could be a major flare at any time ... watch it if you can!
  7. Poor conditions with high cloud & haze ... but the new active area appearing at the east limb is interesting, with flarelike activity and huge filaments to north & south. 2011 Apr 20, 1539 UT. William Optics FLT 110, 2x Powermate, Solarscope SF-100 Ha filter set, Imaging Source DMK41 camera - 80% resize.
  8. Ah, the horrors of summer temperatures ... it's much more comfortable when it's cold enough to freeze the bugs into immobility.
  9. Dangerous ... if you mount is very accurately aligned you should be able to acquire the planets without going to the sun first, then with a slitted observatory you can have the tube in the shade & be safe down to a couple of degrees from the Sun! There's good reason to have the tube shaded anyway - solar heat does no favours to the seeing quality, especially with dark painted uninsulated tubes; and a partially shaded objective will likely have different focuses for the "warm" & "cool" parts. Do not scan for the planets unless you're sure the sun can't get to the objective.
  10. Very nice, the Petavius in particular.
  11. Terrific images there ... probably the best Vallis Alpes I've seen with only 10" ... really excellent, you should be very proud of these!
  12. And without a reflective film on the primary ... making it equivalent to having a huge solar wedge mounted in front of the objective. A conventional reflecting catadioptric scope (with reflective coatings i.e. usable for night time observation) of any aperture is not safe for use with a solar wedge or using the projection method. The heat sink on my Lunt solar wedge gets only slightly warm when used with my 110 mm refractor, I don't know the maximum safe aperture but I'd suspect somewhere around 12". Since few amateurs have access to refractors of that sort of size, I rest my case.
  13. No - the full solar power arrives at the front side of the CaK diagonal and you will fry the secondary mirror for sure. The Baader CaK filter has too wide a bandwidth to be useful, the view it gives is essentially the same as white light. I take it you're aware that most people see very little in CaK, which is very close to being ultraviolet. I see nothing at all ... until I hang a camera on the scope instead of an eyepiece. Lunt sell a 60mm scope with a CaK diagonal ready fitted ... this works; the diagonal can be replaced with a normal star diagonal for "night" observations.
  14. Definitely NOT SAFE there is a good chance of cracking the secondary or melting glue used to attach it. Same applies to projection. The ONLY SAFE way of viewing or imaging the Sun with anything other than a refractor is to use an objective end solar filter made from Baader solar film (or one of the alternatives which are much harder to obtain). These really are very safe PROVIDING they're attached firmly to the objective end of the scope and are always checked for tears, splits and holes before use. A solar wedge is marginally (but not hugely) better than solar film if you're using a refractor. As always, long focus 'fracs work better than short focus ones, unless the short focus one is of expensive triplet apochromatic construction. These days I tend to use a solar wedge except when the observing in public, when I use a solar film filter so that it's OBVIOUS that I'm using special equipment. Projection is less good (though unconditionally safe for your eyes) and there is a serious risk of meting the cementing in modern eyepieces even when a small refractor is used.
  15. The act of observation does not have to be conscious - anything sufficient to collapse the waveform will do.
  16. Linear aperture is linked to sensor size by the angle of view of the lens. The processing can make it appear that way, but the apparent "lower" noise is accompanied by much less detail in the image. You can't have low noise and high resolution without capturing more photons ... the tiny pixel sensors of the small super high density sensors used in compacts is a big downer for image quality.
  17. The Coronado PST CaK is no longer available AFAIK - you might be able to pick one up second hand, though. The Lunt CaK diagonals work well - if you have a decent refractor up to 4" / 100mm aperture and with a 2" focuser.
  18. Yes, faculae. And, on very rare occasions, flares may be bright enough to be visible in white light, one was observed as far back as 1859.I think this image is pretty representative of what can be seen by eye with a solar film filter on a 4" scope at around x100 in good conditions. 2011 Mar 26, 1055 UT. Faculae visible as networks of lighter areas around the active areas near the limb.
  19. Very good programme ... Easy - rickety ladder up to the roof, the inspector won't go up there so you can do what the heck you like
  20. "No contest" - the big barlow is disappointing at its price level, the Powermate would still be good value with the price tag doubled.
  21. Super detail in the NTZ ... just one interesting observation, the rings seem to encroach on the disk where they pass behind at the top right - this must be an artifact of some sort! I know what you mean about variable seeing; but 8 sec of "good" is more than I ever seem to get!
  22. Compacts have tiny sensors which means low sensitivity / high noise. Don't be fooled by the figures ... compare an ISO 400 image made with a compact (horribly noisy) with an ISO 1600 image made with a DSLR (can be fairly smooth). And 6 MP is plenty unless you want to print bigger than A4; in fact 1 MP is more than enough for images to post here. DSLRs also have interchangeable lenses and a decent optical viewfinder. Very useful not having to work afocally for astro work. Build quality is usually better, even for the cheap models at the bottom end of the market. Really there's no competition - DSLR wins by a huge margin. If you're short of money get a second hand one, or a new one of an obsolete model, these often turn out pretty cheap.
  23. The Sun is getting pretty active these days. Three major areas of activity in the northern hemisphere, the group just to the east of the meridian (AR 11190) looks quite "flary" in my Ha closeup. 2011 Apr 12, 1447 UT. Solarscope 60, 2.5x Powermate, DMK21 Interesting activity on the NE limb where a new AR is rotating into view. The bright projection was actually brighter than the disc in Ha! 2011 Apr 12, 1449 UT. Solarscope 60, 2.5x Powermate, DMK21 There is an interesting "detached" prominence on the SSW limb ... 2011 Apr 12, 1454 UT. Solarscope 60, 2.5x Powermate, DMK21 ... and a huge, complex and beautiful one on the NW limb, which shower clouds prevented me from doing full justice to. 2011 Apr 12, 1458 UT. Solarscope 60, 2.5x Powermate, DMK21 I did not get a chance to make observations in white light or closeups in CaK but I did get whole disk images in CaK and Ha. 1415 UT. Coronado PST CaK, prime focus, DMK41 1421 UT. SOlarscope 60, 0.5x focal reducer, DMK41
  24. Very nice! Unfiltered? Did you try a deep red filter?
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