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cloudsweeper last won the day on June 13 2018

cloudsweeper had the most liked content!

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About cloudsweeper

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    Brown Dwarf

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    Physics, maths, history (family, military, social), pre-modern architecture.
  • Location
    Merseyside, England
  1. cloudsweeper

    More Terminator Treats

    Stu - @Stu - I think I must have been looking further south where there was much detail on the terminator, and it was a very clear white oval/sausage - shape hanging in isolation in the blackness, quite lovely. Peter - @Peter Drew - the seeing wasn't bad (as far as I could tell, only going up to x120), but the transparency was bad yet again when I looked out later and could only make out the outline of Orion. Mustn't grumble though - I've had 23 sessions so far this year! Doug.
  2. cloudsweeper

    More Terminator Treats

    5.05 - 5.50pm, Sunday - Moon nearly full, lowish in east, between houses, so I grabbed the chance to view more treats on the terminator, using the ED80 Apo. (It's been all Moon lately, as it goes cloudy after dark.) Mags - x40, 80, 120. Craters west of Mare Humorum close to the terminator led to Byrgius with its floor in shadow and a notch out of its western rim, right on the terminator. Immediately north was a region of overlapping craters, resembling a foot (same size as Byrgius) with two big toes. East of that, a group of three tiny craterlets, then the little de Vico. Continuing NW, the larger Cruger, and further still, a feature of the Cordillera Mountains appearing as a near-complete white oval suspended in darkness. Very interesting and pleasing. I finished with a look at Gassendi, last viewed two days ago, and now very washed out, except for a bent line of six little white dots, presumably a combination of peaks and craterlets. Amazing how much there is to examine in just a small region of our beautiful Moon. And it's different every night! Doug.
  3. cloudsweeper

    Philolaus And Gassendi On Terminator Look Good Even Now

    Well, my last sentence was prophetic. Went out again after a meal to see a hazy Moon, no Orion's sword, and a bit later no Orion. Thank goodness for the Moon, but I would like to see something else as well! Glad you're getting some night action Peter. Round here, it's been lovely clear late afternoons only! Doug.
  4. Ever keen to get stared, I set up the ED80 Apo along with the 8SE on the Skytee, to see what was on show on the Moon. Surprisingly good, considering it's only 4.50pm. Philolaus (a continuation of the Archimedes - Plato line) looked good, sitting on the terminator surrounded by highland detail. Moving to the opposite end of the terminator, Gassendi was also clear - two of its central peaks could be easily made out, and the smaller crater abutting it to the north looked a bit like a cartoon ear. Worth taking a look even while it's still quite light. And you never know when it'll cloud over! Doug.
  5. I got one last year and am very pleased with it. The bearings keep the tube steady, collimation is easy, the focuser is smooth and steady. Being quite fast, sharpness falls off a bit away from centre field, but for visual that is not a problem. Other points: it is manageable, but I am glad I didn't go for anything larger. The finder is all but useless - I replaced it with a nice, light Rigel for finding targets, and a RACI for the wider view and for tracking. I use it on a small homemade platform to get the eyepiece at a comfortable height. It has aperture, magnification, pretty good field. Stars are sharp (maybe not as good as with a frac of course), and lunar detail is fabulous. I would recommend this telescope very highly. Doug.
  6. cloudsweeper

    Three Fine Craters

    Last sentence - same here! Anyway - I liked the ST120, but the new ED80 Apo has really got me into fracs, and now I fancy a Tak with larger aperture. Mrs Sweeper will not be impressed..... Doug.
  7. cloudsweeper

    Three Fine Craters

    Hello Steve - It normally goes cloudy by now, but tonight it hasn't, and I've had a little plonk, so shan't be out again. Typical. The seeing was fair - got to nearly x200. A couple of days ago, I got to over x400 with the Moon. Enjoy your session mate! Doug.
  8. cloudsweeper

    Three Fine Craters

    5.00pm Thurs.. More Moon action, following the pattern of clear late afternoons, then cloud later. (Waxing, past first quarter.) 8SE for a change, and using GoTo, again for a change. I had almost forgotten what a blessing the tracking feature is! I started at x56/1.28deg by targeting the Moon in the RDF. The detail and texture not far from the terminator were immediately evident. Copernicus - x102 - with clear stepped/terraced walls, and with just a little shadow to the east. Its central mountains were very clear. Below it, the overlapping pair of craterlets called Fauth resembled a little "8", largely in shadow. To the north, Mare Imbrium was beautiful, with many tiny craterlets sharp and clear. The biggest crater there, Archimedes, looked very like Plato at the northern edge, both having very smooth floors. Archimedes' shadow from the eastern wall was slightly thinner however, and detail of different levels of the wall were noticeable there. Similar detail was spotted in the SE of Plato's rim. All this was with mags between x185 and x145, depending on the stability, moment to moment. One hour, ten minutes of being immersed in the detail and variety of the lunar surface. Doug.
  9. 4.50pm Weds. - Bresser Dob - sky clearish, but with much thin cloud around. Moon just past first quarter. Plato, north of Mare Imbrium - x159 - jagged shadow cast onto Plato's floor by its eastern rim. Alpine Valley very clear further east. At x212, the view was less stable, so down to x190 and on to Clavius in the heavily cratered south. Very different to Plato, nestling amongst smooth seas. (I hoped to see some of the little pits in Plato's floor again, but light and stability weren't favourable.) The west side of Clavius was on the terminator, arcing through the darkness, and around that region were several small silvery peaks in the blackness looking like chains of stars - a lovely spectacle, and a most interesting region in these lighting conditions. The three biggest craters in Clavius's floor were easily seen, Rutherford (sometimes Rutherfurd) being the largest, with its central peak standing out as a bright spot. All three were like silver rings, with darkened, shadowy floors. I also spotted a fourth and smaller craterlet within Clavius, to the north east. (Three similar ones further west were lost in the shadows there.) One hour and 15 minutes of enjoyment then, with surprises and unusual effects from Luna as usual! Doug.
  10. cloudsweeper

    Most satisfying observations?

    The unexpected sightings: 1. I knew Saturn had rings, but never thought I'd see them. What a thrill that was, and it was in a cheapo 70/700 frac! 2. Jupiter's GRS. It took me 2.25 years to finally crack it. I was doubting it was even there! 3. Seeing the shadow of Mons Piton on the Moon and estimating it was over 34 miles long. Incredible! You really never know what delights await you when you venture behind the eyepiece! Doug.
  11. cloudsweeper

    A quick session with the 72ED

    Good report Rob. I'm looking forward to putting my new frac (Exp Sci ED80 Apo) through its paces too; so far it has mainly been used as a guidescope for the 8" SCT! (But the sharpness of the stars in it is very noticeable.) Doug.
  12. 4.30pm, 11th Feb - got the Dob out to view the Moon (approaching first quarter). Initially, I used x35 to x115 - detail was good, but (because of light) lacked "texture", especially away from the terminator. As on previous occasions recently, I focused on a region which stood out well - this time, the interesting pattern of craters of various sizes to the west of Mare Tranquillitatis. The sky was clear, and the view very stable, so on up to x212. Fine detail, very sharp, so I went on to my max, namely x423, and I was delighted to note the view was still sharp. Tracking was trickier though, and the 'scope was rather wobbly at that level. I dropped to to x317, then x245 - detail was fabulous, and some of that texture was evident, although it was still only 5.25 by then. Rima Ariadaeus was a well-defined "slash" or crack running between craterlets and leading to MT, and with shadow along its northern edge. Another rewarding, short session, characterised this time by very good stability as well as interesting and detailed views. Doug.
  13. cloudsweeper

    EP collection is complete... or is it?

    Some calculus, Louis, yes: M = fo/fe (subscripts) so dM/dfe = -fo x (1/fe^2) The minus indicates that as fe increases, M decreases. For a given 'scope, fo is of course constant, so -fo is constant, which leaves us with dM/dfe is proportional to 1/fe^2. Doug.
  14. cloudsweeper

    EP collection is complete... or is it?

    Me too - I have 8, 6.7, 6, 5, 4, and 3mm. The rate of change of mag with respect to EP focal length is inversely proportional to the square that FL (for a given 'scope), so a small change in FL at the high end gives very little change in mag, whereas the opposite is true with short FLs. So yes - you need fewer long FL EPs. Doug.
  15. 4.10pm (Sun.) - waxing crescent high in the sky, east of south. Sky light of course, and Luna playing hide and seek amongst clouds, but still an enjoyable sight in the Dob (for a change). Clearest detail - craters Theophilus, Cyrillus, and Catharina, to the west of M. Nectaris, and the Altai Scarp beyond them. x35/2.04deg. 4.40 - up to x127 - nice clear view of the craterlet Rosse in the floor of Nectaris, southern region. Crater Beaumont also clear, western edge, with what looks like a broad ridge leading to it. 5.00 - game over, rain started before I got the chance to enjoy Fracastorius when it got a bit darker. Never mind - had some pleasure nonetheless! Doug.

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