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John

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Everything posted by John

  1. I guess the scientists are right now trying to figure out what might have caused such a disturbance.
  2. Some amazing images being returned from the OSIRIS-REX mission to visit tiny asteroid Bennu - including a really surprising particle ejection event: https://www.asteroidmission.org/galleries/spacecraft-imagery/ I'd kind of forgotten about this mission until I came across these latest images. Everything we explore in space seems to provide surprises, puzzles and the unexpected
  3. I do have some Huygens eyepieces somewhere but I'm going to let sleeping dogs lie with those
  4. The funny thing is ...... when I spend an evening observing with my low cost eyepieces, I do sometimes wonder why I have a couple of cases full of rather expensive ones
  5. Nor is the 18 inch NGT newtonian ! To keep the thread on topic (sort of), here is the eyepiece that they use in the scope with a pic of the scope below that. The eyepiece is on topic, the scope certainly is not !
  6. I agree with this. I could see Saturns rings quite clearly when I used to use a 60mm refractor which was about as powerful as your 76mm newtonian. Saturn will look small in the eyepiece but you should be able to see it's rings unmistakably. It should look a bit like this:
  7. My society has an 18 inch F/4.5 newtonian at the observatory. One of the JMI made NGT 18's. I was giving it a clean a few months back (it gets a bit cobwebby) and I noticed that the eyepiece stuck in the focuser was a simple 25mm kellner - basically the same eyepiece that you get supplied with scopes. And thats the only eyepiece they use with the scope as far as I know. Seems a bit of a waste to me but it's not my scope. I might sneak my 21mm Ethos up there and give that 18 inch mirror a chance to shine a bit.
  8. This pair did not cost that much (around £80 I think) but cover from 21.5mm to 3.2mm. I usually take a 30mm SWA (Aero ED) along as well for low / wide observing.
  9. The "stack" gets quite tall when you Powermate a longer FL eyepiece This can have it's uses though
  10. Last night and tonight I've also enjoyed observing the major domes Mons Gruithuisen (Gamma and Delta) and surrounding area. Stu's image shows them very well:
  11. Getting some glimpses between clouds now. The Schroters Valley and environs are really brightly illuminated as you say. Very interesting area
  12. One of my favourites as well Stu but the cloud is not playing ball here. Got the little scope ready to go in case of any gaps though.
  13. Nice report - thanks for posting it The Moon was lovely last night. I was just using my little 70mm TV Ranger but even with that the detail was almost overwhelming with ridges, wrinkles pits and mounds all along the terminator.
  14. This one is F/6.5 but thats near enough !. I've had a good session with a 150mm F/5 newt on the AZ-4 as well but I think I'd go for the 100mm ED refractor for all round ability and portability.
  15. 76x and a 100 degree AFoV with my 12 inch dob. I can spend a long session galaxy spotting with just that one eyepiece
  16. Wow - a 5 year old thread ! I have the 3.5mm Pentax XW but I have not owned or used a Delos 3.5mm. All the reports I've read indicate that the two are likely to be very, very similar in performance so I guess the choice would be over the ergonomics (which are also similar) and the price - bought new the XW 3.5mm costs around £60 less than the Delos. I did compare my XW 3.5mm with an Ethos SX 3.7mm over a few months and concluded that, despite the massive field of view of the Ethos, the XW was a touch sharper so I eventually let the Ethos SX go to a new home. I have the XW's in 10, 7, and 5mm focal lengths so it makes sense to have the 3.5mm as well for high power observing. I have the Delos in 17.3 and 14mm focal lengths and like those a lot. The shorter focal length Delos's have a different focal point than the longer two which might be a little inconvenient if mixed with my XW's which reach focus close to where the 17.3 and 14mm Delos do.
  17. If a newtonian is to perform towards its full potential, I think it's worth checking and tuning the collimation each time you use the scope. It only takes a few seconds. For outreach it's not so critical because you are generally showing folks targets that are well within the scopes capability and they will, by and large accept, what they see through the eyepiece. When you are pushing the potential of the scope a little more and going for the more challenging targets, I feel that it's important to have the optics "on song" so a quick check and tweak is well worth building into the setup routine. Rather like a guitarist adjusting the tuning of his / her instrument before playing.
  18. John

    Carrot7b

    Absolute load of bunkum.
  19. I had a go with my 70mm Tele Vue Ranger this evening. The lowest magnification that I could (reliably) split Rigel tonight was around 40x. It was quite a steady night I think because with the same scope I managed to split Eta Orionis which has a separation of around 1.8 arc seconds. I needed to use 150x to achieve this. I didn't try but I feel that there would be no chance of me splitting Rigel with 10x50 binoculars based on this evenings observations.
  20. John

    Carrot7b

    I think you mean Corot-7b which is an exoplanet apparently orbiting the star Corot-7 ? This was discovered in 2009 using transit photometry, ie: detecting a small dip in the luminosity of the star when something passes in front of it. There are plenty of artists impressions and simulations of this system about but no direct images: Here is a NASA artist impression: https://exoplanets.nasa.gov/resources/305/artists-impression-of-corot-7b/
  21. Scope Skates ! - great idea Do you find that you get any vibrations using the scope on the decking by the way ?
  22. The best views I ever had of Saturn were when it was high in the sky (probably around the time that Stu is talking about). I was using an 8 inch Celestron SCT back then at 250x. The conditions were perfect (which happens just a few times per year here) and the scope in perfect collimation and properly cooled. The image of Saturn looked like the Voyager photos ! But even then I found 200x-300x gave the sharpest and most detailed views. Going over 300x did not add to the image - it was a bit fuzzier although larger but I prefer smaller but sharper.
  23. You should be able to see stars down to around magnitude 9 or 10 when they are close to the Moon, maybe even a little fainter. It's fun to watch a star suddenly disappear as the Moon passes in front of it. Galaxies and Nebulae get really washed out by the Moon though so it's not really much good looking for those when there is a bright Moon anywhere in the sky.
  24. Good advice on maximum useful power above. I rarely use 400x even with my 12 inch dobsonian and that has a top quality mirror from Orion Optics in it. For Jupiter I find 180x - 240x best and for Saturn 230x - 280x. Mars sometimes benefits from 300x but it's so tiny at the moment that even then it's a little pink spot ! The William Optics SPL 6mm is a good quality and comfortable eyepiece with a slightly wider field of view than the standrad plossls and orthos. That would give you a useful 200x with your 8 inch dobsonian.
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