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neural

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About neural

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  1. Agreed - I was in Tenerife earlier this year and went one way with EJ, scope in hand luggage, all else in hold. The scope got inspected after going through the scanner but no questions asked (nor any amusing facial expressions or sotto voce comments, I'm sorry to say). I booked a Ryanair flight to Edinburgh at the last minute a few months ago and was told to put my hand luggage in the hold, so I had a cunning backup plan to take the scope out of the bag and dress it as a baby. Luckily it didn't come to that.
  2. Intuitively it does seem a bit low, but yes it is correct. Whether you can actually see it or not depends on local obstacles of course... diagram.pdf
  3. Good work Doug. Don't be too hard on yourself re 16 Cyg C, it's 12th magnitude which is pretty faint! I like this one for the very similar but fainter double right next to it (unrelated I assume) -- did you notice it? The 'blinking' effect that some planetary nebulae show is not that they flash on and off, but that with averted vision they look much brighter than with direct vision. A lot of them do this. Why it should be planetaries that do this in particular I don't know, perhaps it's because so much of their light is in very narrow bands of wavelength?
  4. Excellent, definitely one of the better attempts at giving you a direct feeling of the size of things.
  5. Good one Nick, dedicated as ever. I'm hoping to bag some of these from Tenerife in a couple of months... I really love those sketches. I cheekily compared them to Stellarium just now - I should have had more faith, they are very accurate!
  6. Cheers guys. I'm very pleased with the setup (though in fairness I haven't used it yet!!). Re balance: in the photos you'll notice that the scope's dovetail appears to be perched rather precariously hanging off the front edge of the mount. In actual fact the mount has a nifty sliding plate thing that allows this arrangement to be solid as a rock, and if you change to a much lighter eyepiece you can slide it back a bit and re-lock it in seconds to achieve that perfect balance. (The 22mm Nagler in the photo weighs nearly 700g.) Also - it passes the one-hand test, and even has a handle on top! Close inspection would reveal a slight discrepancy in the shades of red, although since I hope to be using the scope in the dark...
  7. So I took @parallaxerr's advice and went for an all-Manfrotto setup of an MVH502AH head and MT055CXPRO4 tripod legs (oh and a Baader adaptor). It all arrived in the last couple of days and I had a bit of a heart-in-mouth moment tonight as I set it all up - would it all fit together, and then would it be stable and balanced enough? The answer is yes - I am a happy astronomer tonight (despite the solid cloud cover). Thank you all for your advice!
  8. For me a 'normal good night' is mag 4.5, exceptionally approaching 4.8-4.9. No hint of Milky Way, though I did memorably catch a glimpse of C/2014 Q2 Lovejoy naked eye two winters ago, and binoculars in the Cygnus region when near zenith do give a hint of twinkly milkywayness. I consider myself lucky to be able to say I live in London and to have a sky no worse than this. Also south is my best direction (north is OK for doubles and PNe - NGC 6543 for example - but not much else). The club next door recently installed a second security light right next to the first one (of course that improves your security... right?) so I have to position myself carefully! New year's resolution is to get out more January's job was getting the kit together, and by the end of the week I should have mount and tripod for the new GT81 so no excuses!
  9. +1 for carbon stars. Normally when people say that a star is red or (especially) blue they're not using the words in the same way that they'd use them in describing a pillar box or the sky - but carbon stars are genuinely coloured in a 'good grief look at that it's actually red' way. Apart from W Ori that's already been mentioned, my observing diary includes the following, observable at this time of year, with my descriptions at the time: WZ Cas "deep rich orange-brown with flashes of red" BL Ori "a deep coppery-orange" and "the colour of desert sand" UU Aur "spectacular, splendid rich intense copper colour" U Hya "a beautiful warm fiery ember red-orange" VY UMa "red-orange" and "exactly the colour of Mars" There's also RV Mon, X Cnc and V Hya, among others. In addition to which, they're fascinating astrophysically and usually variable to boot!
  10. I'm selling my 100ED and EQ5 mount both now sold because I've moved on to other scopes and no longer use this one. Both bought new in November 2012, both performing nicely. The scope's optics are great, and it has the original dual-speed 2" Crayford focuser which is a joy to use - I've tightened it up slightly and it works beautifully. There are a few specks of dust on the objective which make no difference optically, a few tiny marks on the tube, and the usual scuff marks on the tube rings. The mount has a few cosmetic marks and the rubber covers for its feet have split. As well as the mount, I'm offering along with the scope: a WO 2-inch carbon-fibre dielectric diagonal (or, if you prefer, the SW 2-inch diagonal matched with scope - in mint condition) a straight-through 8x50 finder with crosshairs a x0.85 reducer/flattener for this scope (mint in box) the original hard case the stock eyepiece I'm looking for £550 for the lot, or make me an offer on parts of it. Buyer collects from SW17; cash on collection, bank transfer, or Paypal (buyer pays fees). Also advertised on ABS UK.
  11. Oh! Oh. Yes. Still no slow-motion controls, but that looks awesome. I will drop FLO an email (unless they spot this thread perhaps )
  12. Hi Chris, that arrangement looks great and the Tak is certainly bigger than my WO. On reflection though I think you're right that it would be a bit heavy for travelling. Parallaxerr: yes I saw your thread from July but thought it wouldn't be sturdy enough. But -- (1) the MVH502AH would be, at least on paper, (2) good point about not needing slo-mo controls if the panning is smooth enough, and (3) there is something I can only call sexy about a small frac mounted like a big lens without a camera: maximum simplicity. Any other thoughts welcome, I haven't made my mind up yet
  13. I've recently become the proud owner of a small bundle of stargazing happiness called a William Optics GT81 (thanks Steve!). This is a good thing, but I can't work out what mount and tripod to use with it - I've read and re-read the relevant SGL threads and I'm still in fits of agony. Help? I want it to be easy to take on a plane, so light and short, ideally rucksack but if the mount and tripod need to go in the hold that's fine. The GT81 plus diagonal plus eyepiece come to 4.5kg, and I want it to handle this easily. I only do visual, not AP. I would like slow-motion controls. Budget is 300-500 pounds. I'm looking at a Giro-WR mount and Velbon GEO E635D. But the Giro would need a 5kg counterweight I think, which would be a nuisance (perhaps not a deal-breaker). A Vixen Porta II appeals, but I think its minimum folded length would be 90cm which is inconvenient for a suitcase. Can you take the head off a Porta II and put it on the Velbon legs? And what about the Borg 3101 - can it handle 5kg? All thoughts gratefully received!
  14. tl;dr: Yes, it is just a simple multiplier. The way magnitude is defined, if one object is 100 times brighter than another, then its magnitude is 5 units 'lower' (e.g. mag 0 compared with mag 5). In other words, magnitude goes down 5 units when the log of brightness goes up by 2 units (10 to the power 2 = 100, so the base-10 log of 100 is 2), and so one unit of magnitude is equivalent to -2.5 units of log brightness. OK so far? Surface brightness is just brightness per unit area, let's call this B/A. So if magnitude = -2.5 x log brightness (m = -2.5 x log B ) then 'surface magnitude' = -2.5 x log (B/A). If you do the algebra this comes out as (-2.5 x log B ) + (2.5 x log A). Since -2.5 x log B is the original magnitude, this simplifies to S = m + (2.5 x log A). Hey presto. Mind you, this only really applies when an object has a uniform surface brightness, which is (to put it mildly) not normally the case. Otherwise it's just a sort of average surface brightness across the object, and I'm not sure how useful that would really be. hope that helps
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