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About acey

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    Deep-sky observer
  • Birthday 10/12/61

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  1. Possible if you really had a clear horizon but in this case it looks like the setting sun may have been seen through distant trees in which case the "flash" could have been a final glimmer of light through foliage. If it was a green flash it would have looked distinctly green - that's how you'd know.
  2. Why not just use one of those things you see in pound shops for mounting a smartphone on a car windscreen? Or even better, just get used to using the finder - far simpler, not affected by magnetic fields, and won't spoil your dark adaptation
  3. Have you ever wondered what astronomers did before electric lights were invented? A candle or lantern could hamper dark adaptation as much as an LED. William Herschel got round it by dictating observations to his sister who sat inside a lit hut. A later astronomer (whose name escapes me) used the smouldering end of a cigar as his red light.
  4. The Viking spacecraft landed on Mars in 1976 and sampled the atmosphere there. A few years later the same proportions of gasses - a "signature" of Martian origin - was found trapped in microscopic bubbles in meteorite EETA 79001 from Antarctica. It was found there because rocks on top of ice fields are very conspicuous and can only have come from above. There are other ways of identifying Martian meteorites from their chemical composition, e.g. the proportions of different oxygen isotopes, and more than a hundred have been identified.
  5. It was his "last lecture" before MIT disowned him due to misconduct and removed his lectures from their site. They can still be found elsewhere online.
  6. Don't get the biggest (largest aperture) scope you can afford unless you're sure you want the weight and bulk that comes with it. You say you mainly want to look at planets, which you can do from a light-polluted site, in which case transportability might not be an issue. But you still need to get it into your garden (if you have one). An 8" dob is a very good all-rounder and very manageable: the Skywatcher 200mm dob is currently £285. The 10" is £429 and is considerably bigger and heavier, the 12" (Flextube) is £529. I have the 12" and use it for deep-sky viewing at my dark site, but it's not for the faint hearted (and not great on planets - my Orion 8" dob was better). If you aren't so interested in deep-sky and really want to concentrate on lunar/planetary you might want to consider a 4" refractor of superior quality: I'll let others recommend one in your budget. Similarly you might want goto, tracking or other frills, which I can't comment on. Edit: previous post crossed with mine and looks a good refractor suggestion.
  7. Ursa Major. Huge (third largest after Hydra and Virgo), visible every night of the year, and packed with DSOs. There are 510 NGC/IC objects in Ursa Major; the only constellations with more are Cetus, Coma Berenices, Leo and Virgo - of which I'd say only Cetus is arguably under-rated. The constellations with fewest NGC/IC objects are Musca (9), Corona Australis (8), Crux (8), Sagitta (8), Chamaeleon (7) and Circinus (5). Sagitta does contain a Messier object though (M71), and is the third smallest constellation (beaten only by Equuleus and Crux). Bootes, incidentally, has 493 NGC/ICs - so I disagree with the previous post!
  8. Names are useful as long as there's only one name per object and everyone agrees on the name. For example, does the "Pinwheel Galaxy" mean M101 (as it usually does now) or M33 (as it did previously) or M99 (which was the first to get the nickname)? Should we call the Owl Cluster the ET Cluster, or the Phi Cas Cluster - or should we call it NGC 457? That's why catalogue numbers were invented. There are so many things up there, it's impossible to remember the name of everything. But agreeing on names makes the task easier, and catalogue numbers (M, NGC etc) are the names with widest agreement. The internet has produced a deluge of new nicknames - making it all the more important to preserve Messier and NGC numbers, so that we all know what we're talking about. No need to remember everything - that's what notebooks are for.
  9. I've often seen aurorae from my dark site in Northumberland (latitude 55 degrees - just a little further north than the southernmost parts of Scotland). Spectacular ones are very rare - the further north you go, the more intense the auroral activity, and the better the chance of getting a really good show. But they never look like the photographs (aurorae are generally not much brighter than the Milky Way). And apart from latitude the crucial factor is the likelihood of a clear sky. Not many people plan a UK holiday on the basis of expecting sunshine (i.e. a clear daylight sky), and the same principle applies at night: if the weather is good you're lucky, but don't bank on it. Personally I wouldn't think of doing an "aurora trip" to Scotland, any more than I'd go there seeking a sun-tan. I speak as an ex-pat Scot who has been sunburned many times in the Auld Country - and has also seen many days or weeks of cloud and rain. The Northumberland climate is much the same - makes me feel perfectly at home... though the talk of Durness etc is filling me with nostalgia for baking-hot days during childhood camping holidays.
  10. NGC404 is not a difficult object; the "ghost" nickname came about because the relative proximity to Mirach led to the galaxy being omitted from some of the star atlases used by amateurs in former decades - it was easy but unmarked. There are many targets made obscure by neighbouring stars. For a serious challenge there's the "Ghost of Zosma" (NGC 3588) - tricky in a 12-inch. But perhaps the ultimate challenge is the "Ghost of Alnilam" (NGC 1990) - which is non-existent, despite being in the second Herschel 400 list. A true ghost!
  11. Interesting, I recorded an unusually bright 20.9 at my Northumberland dark site last night (latitude 55 degrees), also with very good transparency and no cloud. Looks like there may have been auroral activity brightening the sky. Well done on your excellent session: I only did 2 hours and 8 galaxies before deciding I was too tired to continue, much as I hate packing up under a clear sky.
  12. Like the previous post, I use Polaris - cos it doesn't move. I collimate my 12" at the start of every session so need to align the finder too, which takes no time after a bit of practice. As long as an object on the finder crosshairs will be near the centre of field of a high power eyepiece, that's good enough for me. Chasing perfection is a waste of time (same goes for collimation).
  13. Just for info, I have the unlaminated field edition (white stars on black sheets, loose) and the spiral-bound desk edition. I've never used the latter, which has been on my shelf with other atlases for many years: it's just nice to have. I used the field edition with my 8" for a few years until I upgraded to Uranometria (and then Great Atlas Of The Sky which is what I currently use with my 12"). The thick sheets of the field edition are highly dew resistant and I never felt the need for laminated ones. Once or twice I'd have a sheet blow away across my observing field (fun trying to chase a black sheet of paper at night with a red head torch) so a few got mud-stained and battered but remained untorn and perfectly useable. What I'm saying is that the unlaminated field edition is tough. If you want something that'll stay looking pristine then get laminated, but if you just want something that works and lasts forever you could save some money. Best thing was the black backgrounds - none of my other atlases or charts have that feature, and I miss it. I think maybe what made me move on from Sky Atlas 2000 was its failure to plot some Herschel 400 objects, though I could be wrong. They're all plotted in the S&T Pocket Atlas, which I continue to use as my finder atlas, while Sky Atlas has been retired to a drawer (too big and muddy for the shelf). But I do pull it out sometimes for foreign holidays, when a couple of sheets of the area I'll be observing go easily in my luggage, weighing a lot less than a whole bound atlas.
  14. As you can see from the image, it's actually part of M33 - a bright HII region. Depending on the view it may appear as a completely detached object or as a bright outer part. It's not a particularly difficult object from a dark site but is easily overlooked because the rest of the galaxy steals most attention. There are many designated HII regions and clusters in M33 - tracking them down is a good way of studying the galaxy. I've seen the NGC ones with a 12".
  15. Open a burning oven, point an infrared thermometer at it from a distance, and you might get a reading of say 170 celsius. This is not the temperature of air around the thermometer, it's the "black body" temperature corresponding to the electromagnetic radiation that the thermometer is detecting. Take the device into the depths of interstellar space and you'd get a reading of a little under 3 kelvin (if it can read that low). This is not the temperature of space around the thermometer, it's the cosmic microwave background temperature, coming from the edge of the observable universe. The glowing gas of the Orion nebula (or any emission nebula) has a temperature of thousands of degrees. You would freeze in it. The sparks of a sparkler firework have a temperature of over a thousand celsius but you don't get burned (unless you touch the hot metal end). Temperature is average molecular kinetic energy, heat is total energy - they're different. A bath of water at 100 celsius has a lot more heat than a thimbleful at the same temperature. The temperature of space depends where you are, how many particles are moving through it, how heavy they are and how fast they're going. It can be anything from about zero to millions (gas near a black hole).