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661-pete

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About 661-pete

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    Sub Dwarf

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    Male
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    West Sussex and trips to France
  1. Certainly go - and I hope the awful British weather smiles on you just this once! Does it have to be a one-off? Can you not get to a reasonably dark location within a reasonable distance of your back yard (I presume you have means of transporting your Dob around). Check out some local rural sites. Get advice from others who live in your area.
  2. I think we've got a bit distracted from the serious side of the OP by all this 'dark side'/'far side' mixup - which is simply that, a minor semantic slip. I may have been one of the 'poopoo'ers of the earlier thread, if so, I hope it wasn't taken personally! Just that I think it's now become easier, logistically speaking, to put a big optical telescope out into space, where it doesn't need a drive and doesn't suffer from gravitational flexing. But if we want a radio telescope set up in a 'quiet' area, shielded from Earthly broadcasts, then the far side sounds like a good bet. One problem would be, it wouldn't be able to transmit its data direct to us Earthlings: it'd need relay satellites. Servicing and repair of such an installation would be expensive! It costs a lot more to send astronauts to the Moon than just to put them in orbit.
  3. Very impressive. I take it the dark 'bands' are actually the shadow cast by the rings - something we don't see so prominently from Earth because we can't see Saturn at such an oblique angle relative to the Sun.
  4. True, but centring the secondary in the focuser is less critical than getting its tilt right.I meant collimate with the focuser pointing up, not the OTA itself! Unless you're very clumsy you're not likely to drop anything through the focuser tube onto the secondary! The question of focuser flex is certainly a good point, but difficult to allow and compensate for unless you always use the 'scope in the same orientation, with the same eyepiece. Probably best to collimate with the focuser unflexed. And the one thing that's really difficult (I've never tried, myself), is checking whether the focuser is square-on to the tube. I believe a Cheshire will show up that sort of error, but it's often difficult to correct - depends on the mounting of the focuser.
  5. To be honest, if you have not had practice with collimation, a laser collimator is easier to use than a cheshire - although not quite so accurate. Some may disagree, but I would certainly advise you to invest in one - they are not too expensive and you will find it useful to have alongside the cheshire. One snag is that the primary mirror has to be centre-spotted - or to be more accurate, it has to have a small paper ring (like those used for reinforcing pages in a ring binder) stuck to the exact centre. If your 'scope does not already have this, you will have to remove the mirror cell from the tube and do it yourself - it is not difficult but I can understand how some people may be nervous about this - I was! But you only have to do this once. Note that the ring won't affect your viewing in any way. The second snag is that the laser itself has to be collimated before you can use it. There are various guides as to how to do this. The point about using a laser is that you can 'see what you are doing' whilst making the adjustment - especially when collimating the secondary (which you should do before the primary). You can twiddle the screws and watch the spot moving about on the mirror as you adjust: this makes it very easy to home in on the centre. Then, when you go to adjust the primary, if you have twisted the laser so that the cutaway portion faces towards you, you can similarly 'watch what you are doing'. But if you are a perfectionist, your Cheshire is better for that final fine tuning. Do the collimation with the 'scope exactly horizontal and with the focusser pointing upwards. Then you eliminate errors due to the flexing of the focusser itself.
  6. I've had something similar - I won't name names. I ordered a crayford focusser and it didn't fit my OTA, I asked to return it and got the perfectly courteous reply "because there's no fault with the item, and because it's supplied to us by a third party, we can't take it back" etc. etc. I didn't know anything about DSR's and don't remember whether I was within the 7 day limit (probably not). To do them credit, the suppliers did try to help out, they made a sort of home-made adaptor and sent it FOC, but when I saw what they'd sent I decided not to use it. I let the matter drop and kept the focusser, unused: I still have it in its box, wondering what to do with it. Whatever advice I get on here I'm not going to take it up with the suppliers again! 'Sleeping dogs lie' and all that....
  7. That's a nice picture you've got there, very 'atmospheric' (if you don't mind the pun). Shows how, on this sort of photo, a little cloud and haze enhances the character of the image. I saw nothing. The Sun emerged from the clouds at just about 6:00am, ten minutes after it was all over.
  8. Well, if this isn't [exasperation]10, I don't know what is! Clouds parted exactly ten minutes after last contact !!! Got a lovely projection of a completely unencumbered Sun's disk. Ah well, saw the 2004 one in its entirety, so I can't really grumble.
  9. I think I've got an 'old friend' for each season. Orion, of course. Leo to herald the spring, then the Summer Triangle, then the Square of Pegasus and the line of Andromeda to round off the year. But there are others. Sagittarius always being a pain to pick out from British latitudes, I always look forward to it on a summer trip to France (going next week ), where the old 'teapot' stands bright and clear of the horizon. And if I'm there earlier in the year, the familiar quadrilateral of Corvus, for some reason, is something I welcome each time it returns. Why that not-very-striking constellation, I wonder? Possibly because it plays host to the Antennae, one of the most challenging DSO targets for me - and I've had two goes at it...
  10. We don't have to wait for M31, to find out about close encounters between the Sun and other stars. Many of you will have heard of Gliese 710 (if not Google it. Must admit, I had to google to recall the number ) Come 1.4 million years - a whole lot sooner than Andromeda - it's scheduled to pass just over 1 LY from us, shine at 1st Magnitude (currently its mag 9.7) and likely to disrupt the Oort cloud (if it's there) wholesale. Lots of fun 'n' games 'n' cometary impacts expected!
  11. No need for the time machine: courtesy of the HST, we can see beautiful galaxy-galaxy collisions happening right now:http://apod.nasa.gov/apod/ap080224.html Actually, not 'right now' of course, 300 million years ago really. Perhaps we are looking through a vast 'time machine' after all. But one-way only!
  12. If only I'd known. Wasted all that time setting up! How did they contrive it, I wonder? Aha! I think I have it! Evidently NASA set up a 1000 TW black laser (probably sited in Area 51), and allowed the beam to slowly sweep across the Sun. The black wavefront precisely interfered with the light wavefront coming from the Sun, causing a dark spot to appear to drift across the Sun's disk.And they're going to do the same next Wednesday. Have I got that right?
  13. Yes, I think NASA have done their 'hard sums' and come up with an actual time-scale for this event: that's what makes it news.
  14. It'd be great to own one of those - but I think I'd have to upgrade my car too:
  15. M32 and M110 will probably have been completely absorbed into M31 by the time this grand event happens. Some people think M33 is gravitationally bound to M31 - they are only 750K LY apart, much closer than M31 is to us. If so, perhaps it's not that far out to call M33 a 'companion' of M31. We might be looking at a 3-galaxy crash....
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