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About Ruud

  • Rank
    Free-Floating Planet

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  • Gender
  • Interests
    Thank you for visiting my profile. Besides astronomy, I take an interest in photography, skepticism, science, maths, podcasts, radio and cycling. I teach mathematics.
  • Location
    the Netherlands
  1. Centaurus A Galaxy

    It's an amazing result. Detail and colours are wonderful!
  2. The Sun's orbit is determined by the total mass inside its orbit. How much off that mass is concentrated in Sagittarius A* is not relevant to the Sun's orbit. It's the amount of mass inside an orbit that matters, not how concentrated it is toward the centre. Only if the total mass inside the Sun's (or any other stars') orbit increases will the gravity on the Sun increase (or on that other star).
  3. How deep the eye lens lies depends on on the eye cup used (none, normal down, normal up, winged) and whether you use the extension ring or not. It varies from approximately 1 mm to 14 mm. The images here show the normal eye cup folded down: https://www.baader-planetarium.com/en/accessories/optical-accessories/eyepieces/morpheus/175-mm-morpheus-76°-widefield-eyepiece.html This is what's in the box since Jan 2018.
  4. The eyepiece seems perfect in my f/5. I've tried it for a few now weeks and haven't found a flaw. The eye cup problem has been solved. The rubber bit no longer comes off like with the previous batch of Morphs and the included extension ring is ideal. Eye placement is easy and comfortable. For anyone who wonders about coma: the eyepiece is completely coma free. And if your telescope has coma, the eyepiece will faithfully show it in all its glory. Like it shows everything else. Crisp, bright, contrasty and faithful to the edge of the field.
  5. O, I thought a good 200 mm aperture might show an elongated Airy disk for 88Tau. Anyway, I put the finder charts in my e-reader and I'm at least going to try for the visual double tonight. We are near the end of season for the Hyades region, so now is a good time to give it some extra attention. I hope to discover the small open cluster NGC 1662 (blue) and to come to a decision on which of the two neighbours (green) of 88Tau (red) is its double partner. My guess is the nearby mag 6 star, but the title might also go the ± mag 7.5 neighbour.
  6. Thanks, Neptune, for your report. I made two finder maps because I want to find 88Tau myself. Data according to Cartes du Ciel are: Double star -- Component 1 magnitude: 4.44 -- Component 2 magnitude: 6.61 -- Separation: 0.2 (!) -- Position angle: 133. One of the maps has Flamsteed numbers, the other magnitudes. 88Tau is at the centre-bottom of each map and has magnitude 4.25. 88Tau-Flamsteed.pdf 88Tau-Mag4.25.pdf I won't be planning a path myself. There are just too many stars here...
  7. Jupiter, march 08-2018 the best!

    Top class images, Avani. (I actually spotted them on ALPO Japan between the other super Jupiter images there. Your fame spans the world!)
  8. Cleaning a 6" RC primary

    It's a boring little bottle and way overpriced. Ethanol 25% and propanol 35%. About €100 per liter.
  9. Found the ones I remember Steve writing about. They're the LightQuest line. Probably also United Optics. Here are the reviews: http://binocularsky.com/binoc_reviews.php (the four on top)
  10. Oberwerk 15x70 are BA8. They're good, but so heavy! 2.5 kg if I'm right. There's a new line out that @BinocularSkywrote about. Maybe you can find it on his website.
  11. Cleaning a 6" RC primary

    Ha! My bottle is much bigger! It's good to have, but be careful. It dissolves plastics. Only use it as a last resort.
  12. BA8 is a model specifications from manufacturer Kunming united optics. The prisms are BAK4 Characteristics of BA8 are oversized prisms, flat field, good edge performance, high transmission coatings, shockproof, waterproof. They are sold under many brand names. My BA8 7x50s are identical to Fujinon's, but cost half the price. I think Fujinon was not happy at all that everybody could find their identical twins. I suppose William Optics wasn't happy either (not only their BA8 model, but also the UWAN eyepieces are Kunming UO), and quite a few other brands must have been unhappy as well. The Kunming site used to list all their binoculars, eyepieces and telescopes, but now it only shows a tiny subset. BUT On the Wayback Machine you can find older incarnations of Kunming United Optics website: https://web.archive.org/web/20120515000000*/www.united-optics.com On the 2012 Kunming UO website, for instance, you can still see the BA8 line: https://web.archive.org/web/20120414004210/http://www.united-optics.com:80/Products/Binoculars/Giant_Binoculars/BA8_Series/BA8_Series.html (EDIT - I repaired the second link. Hope it works now)
  13. Cleaning a 6" RC primary

    Definitely better. Much better. Maybe, one day, you'll get it as clean as it once was. Meanwhile I hope the mirror performs to satisfaction!
  14. Cleaning a 6" RC primary

    Maybe this helps, someone removes an RC primary mirror, but you have a different brand and size telescope, so this can only serve as an idea of what you may expect:
  15. Cleaning a 6" RC primary

    Sorry about what happened! I can't see any other way of cleaning this mirror without taking it out. The surface of the mirror is probably very sensitive to scratching and dulling. A safe way of cleaning Newtonian mirrors is by soaking them in a soapy solution, placing them under a running tap, more of the same if needed and finally rinsing with distilled water. Then you let the water run off the mirror. There are youtube videos showing this. Best is not to touch the mirror at all. If you can't get this goo off by soaking and rinsing alone, consider gently stroking it while submerged in its soapy bath with cotton, applying zero pressure. The mirror is enhanced coated aluminium. I've wet cleaned an enhanced coated diagonal at least a half dozen times without any trace of deterioration, but that was very easy to remove and put back. Unfortunately you don't have that luxury. If you see no way of getting the mirror off the baffle, there is a far less preferred way of cleaning it with some very soft material moistened with a solvent. If you do that just once you may not notice any damage it causes. You will cause micro scratches though. Personally, I would send the telescope back for a professional cleaning.