Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

AndyWB

Members
  • Content Count

    1,273
  • Joined

  • Last visited

Posts posted by AndyWB


  1. I suppose NOSS Satellites are amongst the oddest that many people see and cannot fathom.

    They certainly were for me, and have come up on here a few times.

    When I first saw them I'd have described them as a UFO, but a quick question on here turned them confidently into an IFO, which is much less exciting.

    But if aliens ever visit, I would like to welcome our new overlords...


  2. So I was out tonight in West Berks, and at 1821 I happened to be looking west with my Mk I eyeballs when something flared. For a moment it became brighter than, well, anything star-like I've seen - brighter than Venus or Jupiter - before dimming just as quickly, though I could see a little spot of light that looked like a satellite drifting off. It was near Pi Herculis, just above the keystone.

    "Ooo" I thought, "I might just have seen my first Iridium flare".

    Heavens-Above does not show any Iridium flares at that time. None of the brighter satellites on it are in the right place at around that time either - and they didn't really feel bright enough.

    Are there other things up there that flare that brightly? I mean, it pretty much seared itself into my retina…  and I'm really curious as to what it was! 


  3. Approaching 2 years at this game, and I've 107 Messiers. I'm missing M83, M68, and M104 (which is an odd one to have missed). I seem to go ages, and then bag a load in a 'big night out'.

    I have been fairly assiduous about tracking them down, and 'seen' might overstate it. 'Found a faintly fuzzy patch in AV that turned out to be in the right place' might be more accurate. 


  4. The Primary mirror is the EASY big. I find getting the secondary right is the hard part.

    The 6 screws should be 3 for adjusting it, and 3 as locking screws to hold the mirror in place once adjusted. I think. I'm not sure which is which, though.

    The screw in the middle of the second picture is the one that hold the secondary mirror on. Think of it as a stalk, with the other 3 pushing the back of the secondary mirror mount to change it's tilt. This image should give you an idea of the overall structure, though on yours the head of the allen screw in the middle would be on the left - it's the philips one in the picture above - and that way round makes more sense to me...

    secondayholderdraw.jpg

    But you get the idea about how it adjusts tilt. You can adjust the middle screw too, if you need to move the secondary towards or away from the primary mirror (to center it under the focusser) - but I'd loosen the other screws first, and make sure the scope is pointed down so that if you accidentally unscrew the secondary mount entirely it won't drop onto the primary mirror.

    Good choice on the Cheshire over the laser.


  5. ... Thread after thread , post after post about the issue, but coma is an inherent aberration with a fast dob, mine shows it.

    Yeah, well I still wonder about that. I mean, mine shows a touch at the edges, but not so much that it bothers me (or even really notice), and only with certain eyepieces (I.e. the 28mm MaxVision. Lovely eyepiece, but my scope makes demands on it). I do wonder about if he got a duff mirror or something.

    ... Eyepieces like the Hyperions will tend to show distortion on stars towards the edge of the view in "fast" scopes. e.g. F5 or lower. This bothers some people more than others, it didn't actually used to bother me that much as I tended to focus in the centre of the view at the time, so the distortion/blur was in my peripheral vision anyway...

    On that note, I did recently get a chance to try each of the Hyperion 5, 10, 17 and 24 mm eyepieces in my f4.7 Skyliner 250px. Now THAT was coma. They were dreadful. All of them, and the 17mm was curiously worse. However, stick them in my f12 or so hydrogen-alpha scope - lovely views.

    So no, I'm not in a rush to use Hyperions at that speed. 

    ... 

    But the way I read the couple of magazine articles I seen it was merely saying if you are viewing in a light pollution area constant then the visual difference between the two would be far less than under good seeing conditions skies.

    My experience with my 5" and 10" dobs is that the 10" still has much better resolution (for splitting doubles), but for DSOs there's a lot less in it, at home under LP. Somewhere dark, though, and the 10" is much better. I think Umadog's reasoning is on the money with this one. 

    My scope grumbles but still gives more than OK views with £50 BST's, it perks up a lot when presented with the £100 SLV's, positively purrs with the £80-£110 MV's and I'm not going to tell you what it does when the £250 Deloses come out to play.

    I've not tried the Delo's but this matches my experience pretty well. And I know they're narrow, but I do like my SLV a lot.

    • Like 1

  6. I compared a 10" SCT with my 10". There wasn't anything in it, really, at the same magnification.

    I suspect that the author meant it was unsuitable because he doesn't like nudging - which is fair enough. Planetary is high power, so more nudging. Doesn't bother me, it might've bothered him. But you can get tracking/GOTO dobs, so you don't have to nudge - though that defeats part of the point of a dob in my mind - or you could put it on an Equatorial Platform, in which case it will happily track for an hour or so. (They ain't cheap, though).


  7. I went after 6 Trianguli the other night, and got distracted by Struve 239, which was just visible as a double at lot power. It had a cute orange colour to me.

    And yes, I did get Gamma Arietis too - it had a weirdly green looking primary to me! (I'm starting to doubt my colour perception!)


  8. From what I've read, Flextubes are pretty good, but perhaps more prone to dewing (due to the open tube), and a heavier (!) than the solid tubes. Personally, I won't bother with GOTO, but I'm a bit of a luddite. A good map 'll see ya proud, lad.

    Setup is the best bit about dobs. The setup process is set down, take off endcap (important), and look. Seriously, so much easier than EQ aligning or configuring a GOTO system.

    They sit on the floor, but the really dinky ones (not an 8" or larger!) can go on a table or box. I prefer to sit next to mine - I use a drummers stool, 'cos it has an adjustable height and is portable.

    They can be big beasts. I have a solid-tube 10" dob and the tube takes up the entire of the back seat of my car with exactly 2cm to spare. I believe the 8" is the same length (and a more forgiving focal ratio, so less demanding on the optics of your eyepieces). They're also fairly heavy (mostly the wooden base) - I'm not small, but I do tend to move mine in two pieces if it's going more than a few feet. I was glad I went and had a look at one first.

    Yes, the dimension usually given is the aperture - so an 8" reflector is 200mm. Refractors of a given aperture are normally regarded as outperforming reflectors of the same aperture, but they cost a lot more, and you don't often see them bigger than about 6". Reflectors offer more bang per buck, but with compromises.

    I got my 10" for occasional "big nights out" and star parties - my 5" sees a lot more use, but for shorter stretches, and in town. It's worth thinking about where and how you plan to use it, and to see one in the flesh first, if you can.


  9. Dont get me wrong, I was planning on taking a couple of photos now and then, will this still be possible without the EQ? 

    Not very well, no. For long exposure photography, you'll want an EQ mount. The problem is something called field rotation: http://www.astronomyasylum.com/telescopemountstutorial.html 

    You might be able to get a few shots of the moon or planets with dob, but proper photography needs an EQ.

    It is possible to mount an 200p dob tube onto an EQ mount, but be aware, it's pretty darn big; it'll need a big, strong mount or any wind will turn it into a sail. Astrophotography is more about the mount than the scope, which is why smaller refractors on big, stable EQ mounts tend to be more popular.

    From reading around here, I've come to conclude that it'd be better to have separate visual and photographic setups...


  10. ... He was a super-enthusiastic character who was capable of thoughtful reflection and, when the circumstances required it, a solid, balanced delivery of factual science.

    ...

    So why is it that people here on SGL seem to rally round and support the format and presenters of a programme that airs once a month on BBC 4 in the early hours of the morning? This stuff should be back where it used to be, on BBC2 before a ten year old boy goes to bed.

    I don't know, they all seemed enthusiastic enough to me in the last episode! That was one of the things that came over in the show - you felt like everyone - project, presenters, press, hell, probably cameraman too - was really excited!

    I remember that the Sky at Night used to be on at REALLY awkward times on BBC2 - either really late at night, or on a morning at the weekend, when I'd occasionally catch it when at school/university, depending on the level of hangover (too little, and I'd be doing something already. Too much, and I'd still be in bed). I actually think it has a much better slot now, though with iPlayer, such things matter less.

    And the think I liked about it (through the fog of last night's beer) was the science. You'd get some funny looking guy (the weird looking ones were all guys) describing mindblowing stuff on the other side of the universe. I was fascinated by that long, long before I even thought about looking up through a scope. It didn't need Brian Cox in the Namibian desert - the wonder was in your head, from some plain studio somewhere. Incredible. 

    I'm just not motivated by much of the current research in Astronomy. It would be more interesting if it was all field based, digging into amateur astronomy. Like Pete Lawrence's contributions, even though it's stuff I already know. That's where my interest lies. The Night Sky!!

    I'm not sure how much field based amateur astronomy content there is. They did do an episode from Astrocamp in Wales, but it's kind of dark, and how much film do you want of other people looking at the sky? I mean, it definitely needs a bit - if only to send the message "You can see this stuff too" - but I think there already is (last episode being an exception).

    And I'm not sure I'd want it to become just a sky-guide. Although reasonably inexperienced, I can spot a certain amount of repetition in the sky-guides. The one approach to a guide like that which might work would be a short guide focussing on a single object - say, something from the Messier or Caldwell catalog - and tie a little in a little science. I heard Pete Lawrence at a star party talking about Epsilon Aurigae and it's oddly long dim cycles, and that was fascinating. I could see it, and he was talking about the science, putting it in context. And I suppose there's the thought that over time, the Beeb could build up a little library of videos on iPlayer about 'stuff in the night sky'. Just a thought.

    Anyway, I thought the coverage of Rosetta was brilliant. Fascinating, exciting, and immediate. Bravo! I must confess, I've watched it twice.

    It might not be perfect, but I'm glad that S@N isn't another 'Celebrity come dine with me dancing on ice in the jungle' show.

    • Like 2

  11. FWIW, there is an OU course about the constellation Orion coming up. I liked the Moons one, except for all the geology. I get why it's important, but there was a bit too much trying to identify unpronounceable minerals. I'm guessing the Orion one will lack that, and it's a fair bit shorter.


  12. I have a 130p and would happily recommend that over the Virtuoso. I just don't think you need tracking, and the 130p gathers quite a lot more light.

    That said, it is not good for photography. As others have said, really, you need an Equatorial mount, rather than a Dobsonian. The only exception that I've had a little luck with is the Moon, just taking afocal shots through the eyepiece. Even that's fiddly, and would get old pretty quickly. E.g. - an iPhone shot of the Moon...

    post-28380-0-57596500-1410350607.jpg

    Edit: If I might recommend, start with visual only (which is much cheaper), and if you want to get into Astrophotography later, then save up and get a dedicated AP setup. They have quite different requirements anyway (Astrophotography is, I understand, more about the mount than anything else)


  13. I guess it depends on your budget, somewhat, and the type of boy your son is. 

    I started with the Heritage 130p mentioned above, and it is very good. However, like all telescopes with mirrors in them, it needs an occasional bit of care (something called "collimation" - essentially, aligning the mirrors). Also, for a reasonable view of planets like Saturn and Jupiter, he'd also want a higher power eyepiece that comes with the scope - something around 5mm focal length would be good. With that, mine shows things like Jupiter and the main bands in it's atmosphere, and the Great Red Spot when it's in the right place, Saturn and it's rings, and surface markings on Mars (though that's small, and it'll be another 2 years before he can see that again). The Moon looks great through it.

    In terms of deep space objects, 5" aperture is pretty reasonable - certainly, under a dark enough sky, it'll show most of the Messier catalog nicely. 

    However, another disadvantage with reflectors is that the image you see is upside down. That's not such a problem for looking at the Orion Nebula (there is no down in space), but it does make it pretty useless on safari. Also, pretty obviously, it doesn't look much like a telescope (hint - all the REALLY big scopes are roughly the same design though!)

    The Star Travel 102 also mentioned above is also a nice choice as it comes with an 'Erect Image Diagonal' - which simply means, the image it shows will be the correct way up, so you could use it for bird spotting, spying on the neighbours, etc.. It's a refractor telescope, so it uses lenses, and this does have some disadvantages - mainly, that they're more expensive to produce, so you get a smaller aperture scope for the same money (and in astronomy, aperture rules). It can also introduce some colour fringing around bright objects. One advantage of refractors is that the lenses are more rigidly held in place, and so they tend not to need aligned during the life of the scope.

    If it were me, I'd happily get the Heritage 130p to start with again - but then I'm not 9 years old.

    You might also want to consider some sort of guide book so he can find stuff. I'd have no problem recommending "Turn Left at Orion".

    Also, this thread might be worth a read: http://stargazerslounge.com/topic/196278-what-can-i-expect-to-see/ 


  14. Mine is f4 and the Paracorr is what makes stars look like stars instead of seagull droppings  :shocked:  :grin:

    Yeah, it's more just that there was a long conversation on here recently about whether 250px's need a coma corrector/paracorr, or if one is desirable, or if it doesn't make that big a difference. There seemed to be a wide range of opinion. In mine, I notice a few stars like seagulls, but they lurk around the edges.


  15. I have chosen to purchase the Skywatcher Skyliner 200P Dobsonian, can't wait!

    Now the question, what accessories should I buy? Including eyepieces, good star maps, filters etc.

    Good choice. 

    Accessories? Well, Ronin's point about eyepieces is good, but that doesn't need to be done all at once. I would suggest to start with:

    • A Cheshire collimator - you're going to want to check the collimation at some point, and this is the tool that can do all the job.
    • A really warm coat and hat - Seriously. Sitting still outside at night in winter = cold. Because you're fairly stationary, I reckon it's colder than Alpine mountaineering at night. There's been a bit of a conversation about the merits of down jackets on here recently. I rate mine as my most essential bit of kit - more so than the scope.
    • An ironing seat or drummers stool - Adjustable height seated observing! I know a lot of people seem to stand, but I'm a big fan of sitting if you can - it's more stable and relaxed (and less troubling to my injured knee).
    • A dim red torch - merely being red isn't enough, you want it to be dim, but bright enough that you can read. Red Nail polish can be a good way for reddening and dimming a torch.
    • A star guide - Something like the book 'Turn Left At Orion', which actually guides you a little more to what you want to see than a map.
    • A star chart - Having a proper map is a good adjunct to a guide book, for when you want to head 'off piste' or when the guide book isn't clear.
    • Then think about eyepieces - I'd suggest around 6mm for your 'highest' power. In my 10" (which I think is the same focal length, so the same magnification for the eyepiece) I find x200 pretty nearly my 'standard' planetary power. It is quite high though - the atmosphere isn't always that stable, so sometimes I'm forced to use less. The low power eyepiece that comes with the scope is probably okay at first, so I wouldn't worry about it too much to start with - though a 30mm eyepiece is probably my most used (for finding things, or looking at big stuff)

    Just my thoughts, pretty much in the order I'd go for them.

    Edit: Oh, and filters - wait a while on that one too. A good OIII filter would be nice on nebulae, but not essential to start. And for the moon, you only need one if the brightness bothers you, and my tip would be that higher magnification dims the image - so if the moon is too bright, try upping the power.

    • Like 2
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.