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Everything posted by billyharris72

  1. No expert on platesolving but I know Astroart does it (used it occasionally and works okay). Astrotortilla looks like a good option and well worth considering. Billy.
  2. We would definitely notice, but the point is a fair one in the abstract. Gasses in space at very low pressures can be at over a million Kelvin, yet the space itself could be (hypothetically) interpreted by us as "cold" if there isn't enough of that gas. The Sun's Corona is an example of this. At about 1 million K it poses comparatively little threat to the Parker Solar probe, which will be travelling through it. What that is "worried" about is the 5800K photosphere - less hot but an awful lot more of it. But for us - I have not actually thought it through in any detail, but I'd imag
  3. Agree with the above. I used to have both - of the two, the Newt was miles better on planets. The short focal length should not be a problem, since 5 inch f5 mirrors seem to be of invariably high quality. It should just be a matter of getting a suitable eyepiece (something about 4-5mm) or using a Barlow to get the required magnification. Don't be tempted to push too high - remember that, given typical seeing conditions (down to about 1 arc second), the human eye can resolve all accessible detail at somewhere between x60 and x120. The other things to check are collimation and expectations.
  4. I'm with Craig. I'd sell it. A 10 inch Dob is quite a big beast if you're living in a city and want to travel to a darker site, and you seem to be happy with the ED72. Sure, a time may come in future when a larger scope makes sense, but that's not now. You might in future consider something like the Heritage Dobs (great scopes - ironically given the advice I'm giving I regret selling mine) on a simple alt az mount (portable, usable from a balcony, but decent light grasp) but for now I'd just stick with the frac. The best scope is the one you use. Billy.
  5. I'd tend to agree with Ricochet. Personally, if your budget is under, say, £40, I'd recommend Plossls as by far the best option. While the field isn't wider than the stock eyepieces, optically they are pretty good. That includes the Skywatcher ones, which are pretty cheap. The only thing I'd add is that a 4mm Plossl is not a particularly comfortable eyepiece to use - eye relief is pretty tight even without glasses. I have one (a Celestron Omni) and quite like it, but it takes getting used to. With that in mind, something like a 32mm, a 9mm and a decent Barlow lens (the Celestron Omn
  6. From the BBC website (science pages): "Skywatchers have been treated to the first full moon of 2020 - known as a "wolf moon" - at the same time as a lunar eclipse."
  7. Good choice. My final setup for grab and go with that scope (which I still regret selling) was the OTA on an AZ4. Portable and absolutely rock solid. Another option is buy a cheap second hand set of tripod legs from somewhere like AstroBoot and just bolt a sheet of plywood on top to make a collapsible plinth for the Dob base. Works well and should only set you back about 30 quid.
  8. The heritage is actually easier to transport - it can be carried in one hand, but you're right about wanting something to put it on. Something like a 3 legged stool would do the job okay though and would not be too much more to carry.
  9. I'd agree with banjaxed. While I don't think equatorial mounts are all that hard to get your head around, the lighter models are often not great. The EQ2 may not be all that stable. I also think the EQ scope you're looking at may have a spherical mirror - not the end of the world, but not as good optically as the Heritage, which is a great scope. What is it about your site that makes you think it may not be suitable?
  10. Have you considered making your own dew heater? I have major issues with dew on the secondary, but loop of resistors drawing around 2 watts, wrapped in shrink tube and attached to the back of the mirror with electrical tape, solved the problem. Going the DIY route also let me use finer wire, so there is no real impact on the image. I imagine something similar could work for the primary? Billy.
  11. Hmmmm, point taken - that's nice! Makes me wonder if I've got something else wrong with my setup. I seem to be able to go both sides of focus, so it's not that, but have bloated stars in luminance and in blue. We're talking really bad here, like a blue fuzzy ring around each star. Removing it in processing leaves the stars looking almost white. I fitted an additional Astromimic UV/IR cut filter, a bit more aggressive than the stock filters. That cleans it up quite a bit - but now I seem to have the focus issue you mention. Only way to get focus is to put the flattener way too close to the
  12. With an unmodded Nikon DSLR you should be fine with the 72ED, and it'd be a good match for the mount in terms of size. It struggles badly with RGB filters on a mono camera (below about 420nm it just doesn't focus), but the DSLR will not suffer excessive chromatic aberration. On the other question, it depends what lenses you have. With an 0.85 focal reducer/flattener you will get 357mm at about f4.9. Having used and compared a budget (c. £80) Sigma 70-300mm zoom at f5.6, my money would be on the Sigma. Yes, the zoom bit and the less than friendly manual focusser are a pain, but optically i
  13. Interesting, and makes sense. I've tended to the exact opposite (pointing up) but down does seem much more stable thinking about it. That might even work with the guidescope setup, as it would be opposite to the guide. I'm really tempted by an OAG though. Do you use one with that DSLR? If so it should cover my chip no problem. Billy.
  14. Hi all: I've struggled a bit with getting a guidescope to work well with my 130 PDS/ HEQ5 setup. I've used three arrangements (all with a 120m as the guide camera). 1) QHY 30mm f4 guidescope, mounted in the finder shoe. Works well, but is a little short so pixel scale / performance could be better. Probably the best setup so far. 2) Skywatcher 50mm ED in the findershoe. Impossible to balance the scope in DEC with this setup - massively front heavy. I suppose I could put a counterweight of some sort at the back. 3) Skywatcher dovetail bar on top of the tube rings with an ADM
  15. My 2p worth - I'd probably go for the 102. As you've said, it's a very compact instrument, light and portable, and still quite capable. More aperture is always good, but it is at the cost of bulk (not that the 127 is exactly huge, but the planned mount is lightweight). On quality, from experience with the 102 and the 150 Maks, Skywatcher can say what they like but mechanically and optically these two scopes are really very similar. There is not some kind of quantum leap in quality once you go above 102mm, just more light grasp (and the ability to use a 2 inch diagonal on the larger models
  16. I think this sounds like a great setup - probably the most common "beginner" astrophotography setup there is these days, and for good reason. The other option (maybe a little more demanding, but with more light grasp, tighter stars and actually less expensive) is the 130 P-DS. To be honest, there's not much in it, and the 80mm ED is by all accounts a keeper. It involves a lot less fiddling around in the dark than a Newt. On the 72ED, I have one and have to say I'm retiring it as an imaging scope. The thing can't focus blue light. It's fine with an unmodded DSLR but on a mono rig the level
  17. Hi Paul. I have the 300mm version of this (bought secondhand from Mr niall) and have been very pleased with it. I'd answer your questions as follows (as always, YMMV). Setup time for me is about 5 mins. I take the scope out in two pieces, put the tube on the mount and that's it. It can be taken out in one, but its heavy and better as a 2 person lift. You'd want to allow another 5-10 minutes for collimation, but do this after cool down. Cooling time will depend on what you want to observe. For planetary or double stars (you have a 120ED, so the use cases where the Newt would give any
  18. Hi all. I'm trying to get my head around this, in the context of stellar physics, and how stars emit both thermal and line radiation. Most of the books I've read seem to cover electron energy level transitions and then talk about thermal energy and black body radiation as if there is no issue to explain as to how one turns into the other. I get the idea of electron energy level transitions, and (to some extent) of collisional line broadening, but I'm struggling to get my head round how these quantum energy state transitions relate to the translational (kinetic) energy necessary to ra
  19. I don't use automatic platesolving that often, but when I have I've used the built in functionality of AstroArt. Overall I've found that to work reasonably well, though Astrotortilla looks to be more powerful. You can also set up Astrometry.net to run locally, though I have not had any joy with that. Billy.
  20. Oh, that's not so good. Not having one of these scopes I don't know if it would reach focus, but it does sound like quite a bit of extra travel. I suppose the other option might be to move the mirror up the tube a little. Billy.
  21. If the sensor needs to be further out then it shouldn't be a huge problem - it's when it needs to go further in than the focusser allows that the problems start. If it won't reach focus a T2 extension tube should get you the extra distance you need. How big is the chip on that camera? Coma will be pretty significant at f4, but won't affect objects in the centre. Billy.
  22. It really depends what youre looking for and at what kind of level. For a gentle but broad and pretty comprehensive introduction to astronomy with minimal maths, Dinah Moche's Astronony: a self teaching guide is great. Ian Morison's Introduction to astronomy and cosmology goes a bit deeper and is another book I'd recommend highly. I've recently picked up a copy of Fundamental astronomy, edited by Karttunen at all. From an initial skim it looks fantastic, but doesn't hold back on the maths. Its not massively complex stuff, but you definitely need to be reasonably comfortable wit
  23. I bought a dedicated observatory tent, and have to say I was not impressed. It was okay once set up, but the construction was very flimsy. The design was really poor, putting way too much pressure on the fibreglass poles. It broke the second time I set it up and was swiftly moved to the bin. Not one of my better investments Personally, I'd stay clear of something marketed as an observatory tent unless I'd actually seen it with my own eyes. Billy.
  24. More confusing to me is Edgar Allan Poe. A man passionately interested in science (Eureka is all over the place but you can't deny his interest), arguably the inventor of science fiction (we'll leave Kepler's Somnium out for now), author of a prose poem in praise of Humboldt. And author of this (warning: what follows is not great). Sonnet - to Science Science! true daughter of Old Time thou art! Who alterest all things with thy peering eyes. Why preyest thou thus upon the poet’s heart, Vulture, whose wings are dull realities? How should he love thee? or how deem
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