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Captain Magenta

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About Captain Magenta

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    Star Forming

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    Middlesex & SW Ireland
  1. I have both editions, and as far as I can tell so far they are extremely similar. I can let you have my 1st edition for £20 all in, pretty much exactly what I paid? The 2nd edition was a bit more and took longer to get hold of, I got it from 365Astronomy in the end after a few months wait until he restocked ... a quick look seems to indicate he still has some at £35 ish but do check. PM me if interested in mine. Cheers, Magnus
  2. When I bought my 300p 2nd hand the finderscope had a simple elastic band in place of the o-ring. It worked fine.
  3. My shaky understanding is this: it’s the maximum amount of deviation-from-perfect-spherical of the light waves after bouncing off the mirror towards focus, measured as a fraction of the wavelength of the light (not sure exactly which colour of light though). 1/10 is very good, ¼ is less good, and what people tend to start to call “diffraction limited”. I'm sure @vlaiv or @andrew s can explain much better... Cheers, Magnus
  4. I think they're available in the "Hen's Teeth" section, or alternatively Hell is getting quite a lot colder these days ... M
  5. Back at you on that - I'm going to use exactly your list for First Light on my new 2nd-hand 200p, once I've re-built it - it's currently completely dis-assembled into almost all its component parts. Enjoyed your report, Cheers, Magnus
  6. The combination of cats and large cardboard boxes is a match made in heaven hell heaven hell heaven!
  7. Arrived yesterday, courtesy of @bendiddley, my new (for me) 8" reflector. Needless to say, I was incapable of unpacking it all on my own, so I got lots of help, as you can see...
  8. ... now been offered one and completed, thanks all. M
  9. Actually an old blue would be ideal. I have a 300p based in dark SW Ireland which I only get to use when I'm there for one of my 3-per-year fortnight visits. To minimise the time spent collimating and setting that one up, and to maximise the time I can spend using it in tip-top condition, I want a scaled-down version in London to practise on and to experiment with generally. I have been offered a 150p but I already have a 6" Mak here so 8" is where I want this one to fit in. Do you find yourself driving within reach of start of M3 ever? Crewe seems quite far away... Thanks, Magnus
  10. ... looking for an 8” SW Newt ... Cheers, Magnus
  11. I have one of these. Superb piece of equipment IMO. Magnus
  12. the error circle was a bit noisy, so I imagine my 24 arcseconds also included the mounting instability error of my cobbled-together set-up Even 24 arcsecs though only represents 0.3-0.4mm of error over 2x focal length of a 1500mm reflector...
  13. They've done just this for the James Webb I believe: a reflective aluminium gold layer on Beryllium...
  14. I recenty acquired, courtesy of a fellow forumite, a Howie Glatter laser collimator, the combination 2"/1.25" 625nm one. It's a real lump. Having read that one needs to be very sure that any such collimator needs to be itself well-collimated, I decided to test mine out over the weekend. I set up my SkyTee2 mount with one of the ADM saddles at a slightly tilted-over angle to form a reasonably solid "V" for the collimator barrel to rest in. I then set up a target A4 piece of paper taped to a wheelie bin around 25-30 metres away up the garden. I rotated the collimator around and made a series of marks where mid-beam struck the paper. I ended up walking up and down the garden a good few times! The result: a non-collimation radius of around 3mm at, say, 26 metres distance, giving a self-collimation error of around 24 arcseconds. I reckon that should be good enough for scope collimation? Has anyone done anything similar for any other brands? Cheers, Magnus
  15. I think the chart is off by a few years; the book was published in 1869, and besides I think at midnight on 15 Dec that year the Moon was bright and up. Not that it makes any difference to the stars’ placement, they’re in basically the same place every year at a given date and time. The actual time looks reasonable to me though when I look it up, of course whatever projection Stellarium is using and whatever implied projection was used to draw the chart will have a major bearing (pun intended) on the relative angles etc of the asterisms. Magnus
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