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Showing content with the highest reputation on 21/06/12 in all areas

  1. 2 points
    I have been waiting for a clear night to test my New Astrotrac on the Milky Way. I am please to say that I was not disappointed considering I live in the Bright City, it handled 5 minute subs easily. This is 20 at 5 minutes, Canon 450D DSLR 18mm lens
  2. 2 points
    ...you can say Uranus without laughing :-p It seems I can't have a conversation with anyone in the office about viewing Uranus later in the year without them rolling over in fits of laughter. maybe I had better concentrate on Neptune ;-)
  3. 2 points
    I am loving this area of the sky so much! Went out again as it was nice and clear but this time swapped the 200p over for my Evostar ED80 with the focal reducer. My goal was to capture the Lagoon and Trifid together. Would you believe it I left my Bahtinov mask at home aggh .. so instead I used a twig in the shape of a Y to get focus and it actually worked Really pleased with this one and it completes my set of images for this section of the sky, just about. Got a few clusters I want to capture but here are all my shots from this region along with my wide-field shot from last night. Wide-field shot of Trifid and Lagoon taken with Evostar ED80 and focal reducer last night with no diffraction spikes for those that like round stars Single shot of the Trifid with 200p Single shot of Lagoon with 200p I am now officially in love with Sagittarius and all the wonders that can be found there its just an amazingly rich part of the southern sky and well worth travelling out in the car to get images from.
  4. 2 points
    Couldn't resist taking a couple of shots of my rose clad obsy in the bright sunlight this afternoon with my pic of Dumbbell from Monday - next two days overcast and rain forecast
  5. 2 points
    I read the weather report on Sunday afternoon that said my local weather would be cloudy Monday morning, mostly cloudy in the afternoon and changing to MOSTLY CLEAR from 10pm onwards, so I was giddy all day at work as I noticed the clouds getting fewer and fewer each time I went out for a cigarette break. I watched the footie then a bit later I popped to the back door for a cig, it was starting to very slightly darken outside, I couldn’t see any stars, but I couldn’t see any clouds either! I was getting really excited by this point. I could see some wispy clouds in the area, but nothing major. After finishing my cigarette I stood at the back door just looking up at the sky, waiting, and hoping the clouds would stay away, then I caught a glimpse of something. A star! It was dim but it was there. Being new to this I got my phone out and fired up SkEye to see which star it was I was seeing; it must have been a bright one. Sure enough, it was, it was in fact Vega I was staring at. I ran in and got my bins out and pointed up towards Vega and noticed a few more faint stars around it; they were now popping up everywhere, dim but there; not so much with the naked eye but my bins didn’t have a problem assuring me there were there and not a trick of the light. I then proceeded to spend a good half hour just stood there scanning the sky with the bins firmly part of my eyes. A few clouds interrupted play every now and then, but nothing major; I was having a great time just scanning! I was so engrossed that actually took me a while to remember Saturn was in my area (I checked the night before on SkEye!). So I fired up SkEye again and searched for Saturn, sure enough it was there on the screen, just up and to my right. I point the phone in that direction and get a circle right where a very bright “star” was. That must be Saturn! Stars are now encompassing the whole sky so I decide it’s time to get the big guns out and finally have my scope outside! I race inside and eagerly grab the base of my 200p, banging it on seemingly every protruding surface on the way out, and place in dead in the middle of the patio with a clear view of Saturn. I race back in to get the OTA, being more careful not to bang this, and carefully assemble it outside and put my stock 25mm EP in. Ready! I point the scope in the general direction of the brightest star I could see, Vega, and look through the finderscope and see nothing but blurs. Oops, I forgot I’d not aligned or focussed the finder! Luckily that was a painless enough process, I pointed it at Vega and got it in focus and dead in the middle of crosshairs then looked in the scope EP and wow, not bad, just off to the left and a little high. A few twiddles of the finder’s screws and bang, Vega dead in the middle of both. All well and good, but I wanted to look at Saturn! Considering this was my first ever view through a telescope, I actually didn’t take much notice of my view of Vega; only one thing was on my mind at this point. I rotated the scope to the right and pointed it at Saturn and looked view the finderscope. I small nudge left and bang, in the middle. I was very excited, and actually physically shaking at this point. I slowly move to the EP and look in…I see a very bright dot, much like Vega really. Must be out of focus. I twiddle the focusser, nope now blurry. I make it sharp again; still just a bright dot. I could clearly see Saturn, but it was just a bright dot. Ah it must be the EP, I’ve only got my 25mm in, I need my 10mm in to see the rings! I swap them over and eagerly look in. I was disappointed. Still just a (now bigger) bright dot. I’d seen images all over the internet from people claiming the images were from a 200p, you could see Saturn, the rings and even the Cassini gap! Maybe my scope wasn’t as good as I thought. Fair to say my enthusiasm was dwindled by now. I got SkEye back up and had a look around for something to catch my eye; since Saturn was a disappointment I needed a fix again. I wave the phone in the air and notice Saturn on the phone screen was a bit right and down than it was before. But my scope is pointing at Saturn, my scope is not pointing where my phone is… I see too dim starts where my phone says Saturn is, one above the other. Nah, Saturn isn’t dim. My phones wrong. What the hell, I’ve got nothing to lose. I point the scope at the new, dim “Saturn” and nonchalantly gaze in to the EP, I’d already seen stars, wasn’t that bothered. BANG! I felt a shudder; my jaw dropped. Bang in the middle of my EP was a beautiful, big, round, orange dot, with a ring round it. I did a double take. Nope, still there. I’m quite embarrassed to say actually got quite emotional at that point, and had tears in my eyes. This was the best thing I’d ever seen; it was truly breathtaking. Saturn. SATURN. I’m looking at Saturn! Live! For real! I literally spent the rest of the night just lovely staring at it, just drooling and still getting Goosebumps (even now, writing this). It turns out the first “Saturn” I’d see was just a bright star, the name Spica springs to mind, but I might be wrong. Eventually it went too low and a house got in the way, so I reluctantly packed up and went to bed (1am by this point!) I really can’t wait to see it again (and possibly some other sights, I got a bit side tracked last night lol) Russ
  6. 2 points
    The Baader CaK 1.25" is quite good although not quite as tight of passband as the PST CaK. It certainly gives you the CaK activity used with a 'normal' scope so inexpensive and worth it to see if you want to invest more. For example: http://www.flickr.com/photos/sherikarl/sets/72157630224160418/ The full disk was taken with the PST CaK and the portion of the disk was taken with the Baader CaK 1.25" filter and Baader ND 5.0 filter film on a 110mm refractor. Hopefully this illustrates a bit about the difference in detail resolution you can get. I've not had a chance to try the Lunt CaK diagonal although the images I've seen on SGL look very good. Cheers, Sheri
  7. 2 points
    Psst... Hebrew and Yiddish aren't the same thing Hebrew is the language of Israel and the Jewish religion. Yiddish is a type of German originating with the Ashkenazi Jewish population and is a fusion of some regional German dialects, Hebrew and Slavic and a wonderfully expressive language in it's own right. It's sometimes written using the Hebrew alphabet though A gezunt ahf dein kop
  8. 2 points
    Here's my intro. I am 38, live in Tiptree Heath with my Wife, no kids, just fish and Chickens. I have been into Astronomy for about 2 years and am now starting to delve into AP with my SW 250 PDS/NEQ6, ST80 guiding with QHY5v and imaging using a Canon 1100d. I am an active member of North Essex Astronomical Society who currently have a membership of 122! so there must be loads of astronomers in the whole of Essex. There's a few of us going to Kelling in Sept so perhaps we can look out for each other. I've never been to a star party, but it sounds like an idea to put a sign on your tent with your SGL name, so people know who you are? Andy
  9. 2 points
    No it isn't arabic, it is Hebrew!!(yiddish) shalom, Den.
  10. 2 points
    You could use it to listen to radio waves scattering of meteors entering the atmosphere. I see it does fm. Look online for a radio station to the east of you thats over the horizon, at least 50 miles away. tune you radio to that frequency but make sure you can't recieve any local stations on the same frequency. When meteors enter the atmosphere sometimes they scatter the far away station you can't normally pick up over the horizon and you can hear them or a whining sound. On my phone so difficult to go into detail at the moment but you could google ' fm meteor scatter'. Lots of stuff on the net about it.
  11. 1 point
    Every now and then, I see one mentioned in various posts and thought a thread might be a collection point for those new, as well as experienced observers to share their tips and tricks for visual observing only. To start the thread off: Averted Vision - Looking slightly to the side of a faint object to bring out more detail/brightness. Jiggling The Image - Helps bring a very faint object into view and increases some detail by tapping the OTA or slightly moving it. Floating By - Let the faint object float through the FOV. The slow movement makes your eye "re-capture" the object over and over, which helps bring out hidden details and helps detecting the faint object. Observe At The Zenith - Where haze and light pollution is less and faint objects can be detected easier. I could list many more but its time for your tips and tricks to add to the list. I'm sure, beginners especially, will not want to spend time reading (and learning) a tip that's several paragraphs long so hopefully yours will be short and to the point. Thanks in advance to all that contribute to this thread and I hope we all can benifit from these tips and tricks - whether we are beginners or experienced observers.
  12. 1 point
    Got Moonraker m8 air control radio scanner i shall use it to listen to them planes or anything else that mite fly past sometime got one these from maplins only 19.99p thought i'd get one listen to airband as lot planes fly past. http://www.maplin.co...and-radio-46459 what use could me mini scanner be used in astronomy ?
  13. 1 point
    Hello, my name is Phil. I'm 45 years old, and work in IT management for a large financial institution. I spent many years programming in various languages, including Java, C++, Ruby, Smalltalk etc. When I was about 25 (?) I bought a small Tal-1 reflector, as I'd been interested in astronomy as long as I remember. It cost well over £100, which 20 years ago was a not insignificant amount. I looked through the scope a handful of times, seeing the crescent of Venus, M42, Saturn (though could never make out the rings - I'd never heard of collimation, and the scope came with instructions n Russian!). After that, it had to be moved into the loft to make space over winter. After all, I wouldn't be outside using it in the freezing cold, when the nights in summer were nice and warm! So it moved to the loft, and it stayed there for about 20 years, untouched. In the meanwhile, I bought a few occasional copies of Astonomy Now or Sky and Telescope, and began to realise a few things. Firstly, of course, that Autumn and Winter were actually the best times for observing, and secondly that I wasn't really going to see a huge amount through my 4.5" scope beyond tiny planets and faint fuzzies. So I started to lust over the Meade and Celestron SCT's in the big adverts, but they were many thousands of pounds. I figured if I lived in Arizona, I'd be prepared to spend that amount. But not in Manchester. So I stuck with following stuff in AN and New Scientists now and then, resigned myself to not having a telescope, and the poor Tal languished in the loft. Then last year two things happened. First, I found SGL, and I realised that actually, a 4.5" Newt, whilst small, could actually be quite an exciting little instrument. And secondly, I noticed the Dobsonian aperture revolution that had occurred in the 20 years since I bought my scope. An 8" scope for well under £500??? A 10" for well under a grand!!! Inconceivable! Scopes that size cost half a years wages 20 years ago. Now they were costing less than a weeks wage!?!? Two things followed from this. I began a rebuild of my Tal, with the intention being to alter it to accept 1.25" eyepieces (I had lost the 0.96" eyepieces it came with), and I began to research the purchase of a bigger scope. The Tal rebuild came to a halt when my wife threw out the tube. Someone offered me a replacement, and I need to dig out that old post, because I'm realising now how generous that was. The scope research took a year. In this year I've spent a lot of te reading AN, SAN magazines, books, and probably best of all, SGL. So I know a little bit more now than I did a year a go, and WAY more than I did 20 years ago...but it's still 20 years since I last looked through a scope, and so I count myself as a complete beginner. In the year spent researching the scope options, I made a few decisions. The first was to avoid astrophotgraphy. Had this still involved hypered Velvia, then maybe I would have been interested, but the thought of coming home from 12 hours wrestling with computers, to then spend more time wrestling with computers, filled me with dread. As much as I'd love to give it a go in ideal world (and if I win the lottery, I'll have an AP rig to shame a few minor UN states), in reality, I just can't face it. So that meant I could really benefit from the Dob revolution. Second was goto. I know this stirs conflicting opinions on an almost religious scale. However, the reality again is that if I spend 12 hours in the office, 2 hours driving, 6 hours sleeping, an hour eating and saying hello to missus, and 2 hours 45 minutes watching the rain, I want to spend the remaining 15 minutes seeing things, not looking for them (figures given are averaged). Your view may vary. The third decision was budget. Having a fairly decent job, and a very understanding wife (who is looking forwards to the new scope as much as me), means this is much less of an issue than I had feared. This means I was able to consider some largish scopes, and some decent eyepieces and accessories. After looking around, I eventually started to settle on a flextube, in the 10-14" range. One of these would fit in our car (when there is just the two of us - i.e. 90%+ of the time), give good views, and leave budget for other stuff. A visit to Opticstar in Sale to view a 12" Auto finally convinced me this was big enough, and the 14" probably a step too far. So, I took the missus down for her to see the scope, and whilst she was fairly surprised at the size, her first reaction was to start planning storage and transportation logistics! Result! Her second reaction was to say "So are you going to order it now, whilst we are here?"! Stunning result! Now, I knew Opticstar didn't have any in stock, and that neither did OVL. But I did know that at least a couple of others did have what I wanted ready to despatch (this was around the middle of May). However, on my two visits to Opticstar, the staff had been so helpful, enthusiastic, patient and generally brilliant, that I decided I'd rather buy from them, as my local (ish) physical shop. This seemed oth more fair, and in the long run better for me in supporting a local shop, than take their advice for free, but then take my money and go elsewhere. I knew it would mean waiting, and Sathya did say to me several times before I placed the order that it would be some weeks - middle of June earliest. Having him deliberately give me the opportunity to shop elsewhere, after all the help they had given, just made me more determined to order from them. So, there's the situation. I've ordered a Skywatcher Skyliner 300p Flextube SynScan GoTo Dobsonian, and I'm awaiting delivery. Latest estimate is that the shipment makes landfall in the UK on 20th June. We all know from FLO's wonderful transparency that it can take some time after landfall before the shipment makes it to OVL, so I'm not yet holding my breath. In the meanwhile, I bought a Cheshire, and I've read just about every guide to collimation I can find online (including the one by SGL's very own AstroBaby, of course!). The purpose of this blog will be to document, as it describes itself, the fumbling steps of a beginner. Perhaps some of the information I post, and descriptions of the mistakes I make, may help other beginners. Maybe it will give more experienced people a chuckle. I'll be every pleased if I achieve either of these things!
  14. 1 point
    Before anyone reads this, I suppose it's just a few observations of my journey in imaging thus far, nothing more, nothing less. If you don't want to get bored and would rather watch paint dry, then please do - Watching paint dry may be more useful to you I have discovered in 18 months that there are a number of things in imaging that I have severely under estimated. I say severely as I have ignored things at my peril thinking that it 'would do' or 'couldn't affect an image that much'. I wish that I'd paid more attention to these things and not dismissed them as non issues. Perhaps someone will read this and think about what their problems may be and perhaps they have been as guilty as me! 1) Polar Alignment - I have read people ask if polar alignment is THAT important, and I have to say that it is probably the single biggest thing that has blighted my imaging. I used various methods to check PA and thought it was OK - Until I finally got a grip of it and realised how far out it was and how it absolutely stopped me getting round stars. I can not emphasise enough how important this has been in getting round stars and non trailing images. 'That will do' in reality probably won't. 2) Good optics - Recently having got a scope with what is considered to have good optics, and already having a scope that had, I thought, good optics - They are like chalk and cheese. Boy what a difference that made. 3) Getting exposures in hours - I have been so guilty in under estimating how much exposure time you really need. For me now, a couple of hours just won't cut it. I will gladly run into 15 hours plus. It makes a massive difference. I have been as guilty as anyone else of getting 30 mins and thinking that's it - But really push for more and more, it makes a world of difference. 4) Good focuser - Having been 'blessed' with a standard Skywatcher focuser, changing it for a Moonlite and then getting a scope with a decent R&P focuser, I want all scopes to have a decent R&P focuser. They are a joy to use (far more so than the Moonlite even) and really can not be beaten, for accuracy as well as load bearing. I think I've turned into a Crayford disliker, even the premium ones. 5) Guiding and high cloud - You know when we image from night to night and there is NO difference at all in our setup's but on that second night we cannot get a good guiding graph and it's all over the place. I would never have believed what high wispy and almost imperceptible cloud can do. In fact until last week I still didn't believe it, but my proof was there. Guiding goes well on clear nights. 6) Processing skills - Ahh, still learning that one!! I think that when we start out we all under estimate the amunt of time as well as the amount of knowledge required of various processing packages to start getting a half decent result. You captured 10 hours worth of data - Add another 10 hours to that in processing. I'd love to see people putting a processing time by their drop dead gorgeous images, I think we'd all be shocked. 7) Effect on bank balance - How on earth did I get THAT bit so wrong? I started out with £2k for an imaging setup (minus camera) - Woops, I think now I'm slightly over budget!! This hobby is devastating on the pennies. 8) Importance of focusing - I never really got that this can make or break an image. I thought a quick focus would do it, but no. I found that to get good focus I can spend literally 5-10 minutes on it. Never under estimate the difference between alright focus and nailed focus. There's a few more, but I'll not go on. I hope that I don't sound like a complete know-it-all as I'm really not and not half as much of a twit as I probably sound! It's just that these few things have had such a profound effect on my imaging that I thought by writing them down they may strike a chord with someone else. Happy imaging!!!
  15. 1 point
    Currently I'm gathering data for an image of the Cederblad 214/NGC 7822. I only have two nights H-alpha now, but will record more of this in the coming time. This is a teaser of what I have now: Takahashi FSQ-106/SXV-H9/NEQ-6 10x1800s Ha (4,5nm)
  16. 1 point
    Hello every body, After long time with out astronomy imaging, I have shot this night because the sky were nice and the turbulence quite. So the first image has been done in Luminance around 08:12 pm UT during 1'35" and exposure time 15 f/s: Now, the LRGB version: Franck
  17. 1 point
    The RASC here in Canada put together a web page showing highlights of everyone's efforts - all across the country - to see the 2012 Transit of Venus. My own blog is included there (with the transit cake). http://rasc.ca/transit-2012-results It's the first event I can remember where it seems everyone was observing the same thing at the same time from coast to coast. I have to mention that it seems like the whole country got to see the transit except BC which is normally the shangrila of good weather! When does Mercury next transit?
  18. 1 point
    After weeks of waiting for the sky to clear, I managed to have a play with my xbox webcam and captured this.
  19. 1 point
    In this video, I thought it would be helpful to give beginners an overview of the summer constellations and brighter stars, starting with the rising Summer Triangle, and then moving towards the south, and finally towards overhead to identify many of the larger, dim constellations residing in that portion of the sky. Also covered is solar observing and astrophotography, given the significant daylight due to the solstice occurring this week.
  20. 1 point
    I am thinking of taking out a subscription to the sky at night magazine as I want to learn more about astronomy as I really love my telescope and thought it would give me something to read on the cloudy nights. Do you think it is very useful to a beginner as I don't want to receive a load of magazines full of things I won't understand as I'm very new to astronomy. What do you think?
  21. 1 point
    Hi everyone, a couple months back we were doing an experiment with microscopes in a science lesson and was told to record what we saw through the microscope. My teacher told us that we could try to use our phone cameras to try and get some pics. The outcome was successful. Anyway this gave me an idea to try this with a telescope and I was suprised with the quality and ease I could get pictures with this technique. This is my first attempt at astrophotography and I think it went very well. Here are some pictures I took: This is one of the first images I took of the moon. And then here is one of the best that I could take. The telescope I have and used for these images is a meade etx 80. Please let me know what you think, thanks!
  22. 1 point
    On the contrary I like to be 'out there' and under a full open sky. My obsy's only function is to speed up set up times. When the scope and cameras are doing their stuff I'll be stood inside (or maybe outside) gazing up or scanning with binoculars. Meteors, satelites, UFO's - you really could miss so much tucked up inside a dome!
  23. 1 point
    Hi Gina - I think we've been down this route before which I already answered - my DIY obsy homepage linked below explains. Contrary to your opinion domes are not difficult to build if kept lightweight - some confuse massive structures with strength but this nonsense and trap for the unwary . You do have a point about dome rotation and long exposure AP but that doesn't apply to me - I just give the dome a shove when aiming in a different part of the sky and keep my gross exposures typically less than 5min. My M57 below from Monday night in late twilight has had an extremely brief 20s exp but still shows the central two stars and hints at the faint field galaxy. OK I'm not a perfectionist [i don't need to be in my SN searches] but I'm mystified by the long exposures routinely used on the forum with seemingly little to show for it. This must be very frustrating for newcomers to AP learning their way.
  24. 1 point
    I have now spent quite a bit of time re-processing it, so this is the same image again re-processed with a bit of selective High pass filter. Much happier with this even though the extra stretching has revealed more of the noise. Carole
  25. 1 point
    well I have just given up with you Harry
  26. 1 point
    Hi Folks, Thanks for all the nice comments! I posted this in the beginner's forum rather than the photography forum for a very specific purpose. I often see new members here asking things like "How can I get started in astrophotography?" Typically they want to know what sort of scope, mount, camera combo to purchase to 'get into' astrophotography. My point is quite simple - use what you have to hand first! This wasn't a planned photo session, and we didn't do anything special to facilitate a good photo. Even so, this is one of the best single frame exposures of Saturn I've seen from a small (133 mm) aperture scope with a (decidedly!) amateur camera. Until web cams and digital stacking, few amateurs could get exposures this good with a single shot. The ubiquitous smart phone is something that I would suspect that many amateur astronomers have in pocket when they go observing - so why not give it a go? My (former) student, Michael Fish rather pioneered shooting astro photos with his android tablet when he was in my astronomy class. I'd had many students try photographing through the EP with cell phones in the past few years, but until recently the cameras on such devices were much too poor to acomplish much of anything. Michael's photos of the Moon taken with his 7-inch android tablet (sorry, I don't know what kind it is...) have been published and his work has gotten him a scholarship and he plans to continue his studies in furture at a larger university. Technology has taken another mighty leap forward friends! Get out there in the dark and give it a go! Dan
  27. 1 point
    Pack the scope away during high summer ? Not a chance, there is always something to see. It's a big sky and it's free. Just set yourself different targets.
  28. 1 point
    Finally got around to processing my 2x barlow series of the transit with the PST. I'm having a devil of a time getting the subs to line up. PS photomerge is being obstinant. I haven't had much luck with the weather for planetary, and I've only managed get one day for solar. Here are the results for both. I'd like to hear peoples suggestions for making photomerge work a bit more consistantly... what's the trick? More overlap? Comments and suggestions always welcome. Cheers Tim
  29. 1 point
    But its still nice just to touch and look at. and look through the eyepiece at the wallpaper which is so out of focus cause your 2 million miles too close LOL.
  30. 1 point
  31. 1 point
    Nice scope Malc, congrats. Had a gander through one of these a while back. Very nice
  32. 1 point
    Here's my intro, Im Alan 56 I live on Shooters Hill in London with my wife Sue, I have 1 daughter and 2 granddaughters I,ve been into astrophotography now for about 18 months now I find I never tire from the subject whether Im on the forum or watching someone video tutorial it brings me great pleasure. I know that without the help from members of this forum I would not be in the position I am today with what I have achieved. Regards BigBlueOne.
  33. 1 point
    Hi, I have used my 9.25" SCT and Go-To CG5 mount for 6 years now and can vouch for it. The polar scope is not heavy and can be removed before attaching the OTA. I have managed to carry mine down from the bedroom to the yard (so far without incident!) making 4 trips (tripod and mount/counterweights/OTA and eyepiece collection, power supply etc). Cheaper than a gym workout too. Being retired means I can stretch out the trips to my own pace and have the tube nicely cooled for when it's needed. Hope you enjoy yours. Cheers, Steve
  34. 1 point
    Cool photo's Hereis a couple of mine taken with a HTC smart phone , hope they come thru . Theres some good photos taken with my camera phone . Brian.
  35. 1 point
    Decided to repro some images from Jan 14th using AS!2 as previously did a animation of Jupiter and moons which were stacked in Registax. This image was done using 1.5x drizzle and has produced some pleasing detail on Ganymede!
  36. 1 point
    Malc, don't worry about the polarscope weight, once you've aligned, it removes for use.
  37. 1 point
    Leaving aside colour, there are two kinds of light pollution: glare and skyglow. If you put one streetlight in a desert at night and stood next to it you'd be dazzled by glare and wouldn't see many stars. But if you put a screen between yourself and the single light that's bothering you (and if the air is clear) then you'll see a black starry sky. On the other hand, suppose you've got twenty thousand streetlights in a town a few miles away and you're in the countryside. Then the sky above the town will glow from the light of all those lamps being scattered off vapour in the air. Depending how many lamps there are and how far away you are, this glow could potentially cover much of your sky. If you're inside the town then it will cover all of the sky. In that case, shielding the single streetlight you happen to be next to will cut glare but will do nothing to reduce skyglow. Glare stops your eye adapting to darkness: when you step out of a bright house at night everything looks black because your eyes aren't adapted. If you've stepped into a garden lit by streetlighting, security lights etc then your eye will adapt to that level, which is still a lot brighter than a truly dark sky. Even if you can't see the light sources directly, the ambient light on the ground, buildings etc are a source of glare. Skyglow makes the sky brighter meaning that stars etc have less contrast against the sky. During daylight the sun creates a huge amount of skyglow which is why we don't see any stars. The moon has the same effect at night: a full moon washes out the sky when seen at a dark site. When you look through a telescope you see objects against a brightened sky, meaning that you see less. A good and simple way to estimate the extent of light pollution is to check your naked-eye limiting magnitude, i.e. find the faintest stars you can see with the naked eye, and check their magnitude using Stellarium or something similar. Ursa Minor is useful for this: if you can't see all the seven main stars then you have significant light pollution. If you can only see 3 then it's very severe (limiting magnitude 3 to 4), if you can see 4 stars then your magnitude limit is around 4.5, if it's 5 or 6 stars then your limit is between 4.5 and 5, and if you can see 7 then your limit is better than 5. With a limiting magnitude of about 5.5 you'll see 9 stars in Ursa Minor and the Milky Way should be faintly visible, with 6 the Milky Way is easily seen and the sky can be called truly dark. My back garden is 4.5 and nowadays I do all my observing at a dark site which is 6+, but when I started out I did all my viewing from the garden, without any kind of filter, and I still managed to see quite a lot. A light-pollution filter is meant to cut skyglow, so that when you look through a telescope you see things against a darker sky, which is meant to improve contrast. Of course, the filter also dims the object you're trying to see. So in order to work, the filter should really be cutting more light from the background than from the object: this is how a nebula filter works, or a neodymium one used when the skyglow consists of low-pressure sodium light. In the garden, try screening yourself from glare (a hood over your head should do it), and if you want to try a neodymium filter to deal with the skyglow then give it a go. It may improve contrast on DSOs, but if the skyglow has a lot of white in it (from high-pressure lighting in other parts of your town) then you may see no difference. For moon and planets, skyglow is not a problem, these objects are very bright and the only filter you may need is a neutral density moon filter so you don't get too dazzled (though don't worry, you can't do your eyesight any harm by looking at the moon through a telescope of any size). Skyglow will limit the faintest stars that can be seen, but many double stars and star clusters can be seen from a light polluted site without any kind of filter (e.g. the Hercules globular cluster or "ET" cluster NGC 457, and doubles such as Albireo, Mizar/Alcor or the "double double" in Lyra). For emission neulae a nebula filter such as Lumicon UHC is the best thing if the view needs enhancing, though again, planetary nebulae such as the Ring, Eskimo or Cat's Eye (and also the Orion Nebula) are bright and can be seen well even at light polluted sites without a filter. With galaxies, there are a handful that can be seen easily from a bright site (M31/32, M81/82) though in general, there's no substitute for a dark sky. Main thing to remember is the distinction between glare and skyglow: ideally you want to deal with both, not just one, but if you can only deal with one it should be glare. Attempting to deal with skyglow using a filter is hit and miss and it may be that the only real answer is to get to a dark site, and if that's not an option then too bad. In any case there's a lot that can be done from a light polluted back garden, just don't expect to be able to do everything.
  38. 1 point
    You'd be amazed what you can get in a 10 " dob ota
  39. 1 point
    Hi Knobby, thanks for the welcome. Ok then, here goes with the 'standard letter' as suggested. Dear Sir/Madam, I am a member of (state organisation) and am concerned about the large number of floodlights that have been installed at the Wallasea Island Wild Coast Project. The Dengie Marshes are just across the River Crouch, and it is a favourite location for Essex astronomers. The much lower levels of light pollution are favourable for visual observing and imaging the night sky. It is very difficult to find such an area in Essex. Some Essex astronomers travel large distances to find other suitable sites, so the whole Dengie area is important to us. At night, light glow from bright lighting carries for a considerable distance. From the Dengie Marshes the glow from Southend, Burnham, Maldon and Clacton is readily apparent. The much closer lights at Wallasea are a great concern to Essex astronomers. Please be assured that I am in full support of the Wallasea project. It will be a valuable resource for protecting wildlife and be a great place to visit. I wish the project all success. I do understand the importance of providing a safe working environment for those working at Wallasea, especially at night. However, as mentioned, the large number of floodlights at Wallasea is a concern. So I am asking if the number of flloodlights could perhaps be reduced, or at least pointed downwards. The horizontal positioning of the lights means that they will be very apparent for many miles. If they could be angled downwards, that would help to lessen the light pollution. On the safety aspect, horizontally mounted floodlights are just as likely to cause an accident as to prevent one. A bright light shining in a persons face can make it difficult to see a hazard. If the the lights are aimed at the ground, then the area is illuminated, and workers less likely to be blinded by the flloodlight. Thank you for reading this. As already mentioned, I wish the Wallasea project all success. Very best regards (state individual or organisations name ) Please send to wallasea@rsbp.org.uk and feel free to alter as you think appropriate. I really do think that a polite and understanding approach to this issue is more likely to get a desired result however steamed up we may feel. To all those who can help sort this, thanks a bunch Ed.
  40. 1 point
    Here is a quick review on some Strathspey 20x90's to give you an idea of the views you will get. There is a Part 2 at about post 13. http://stargazerslou...t/#entry1191414 Personally I love binoculars for their apparent 3D, ease of use, no messing with eyepiece choice, relaxed viewing in a chair, better views under my heavily light polluted skies, easier to put away and call it a night when the clouds roll in, not a huge investment, great for daytime use, travel, holidays etc. I sold the Strathspeys because they had infuriating sloppyness in the eyepiece crossbar, requiring me to constantly re-focus. The views were great. Since then I have tried a 120 Evo , a C6-N, and a Skymax 102 Mak. I am going back to some large binoculars as soon as funds permit. They just seem to suit what I like to do and how I like to do it. Paul
  41. 1 point
    So do I! Seriously, SaT is a great mag for all levels. Just picked up the July issue and it looks good.
  42. 1 point
    Glyn, This is not a great deal in PI. Create a star mask, apply to linear image, go to a stretched mask script, set to 100 iterations, watch the whole football game; when it's over, PI will be ready with a lot of nebula and suppressed stars. You can also reduce them with Morphological transformation. May look like this in the end - http://astrobin.com/2546/
  43. 1 point
    Sharpcap is good for planetary images not DSO's. Backyard is designed for Canon DSLR's and controls the camera completely. It is easy to use and produces great results. Backyard saves images as RAW CR2 files which you then stack in Deep Sky Stacker then process in Photoshop or GIMP. Basically Sharpcap saves images as AVI files and is normally used with webcams not DSLR's. If you are going to be imaging DSO's then BYEOS is the way to go although there are similar products such as APT. If you are just doing planets, then you don't need the Canon! BYEOS is reviewed in Sky at Night mag this month. The best thing you can do though is to get a copy of "Making every photon count" which is available through FLO.
  44. 1 point
    Mirrors need a different technique than glass lenses. Have a search here on SGL or a google search. I've always liked this version....... http://www.astro-baby.com/TAL%20Telescope%20Rebuild/Telescope%20Mirror%20Cleaning.htm But I do it exactly as in this vid....... Be aware that the coatings Tal use are vey very tough, so the aluminium layer on the glass, under the coating, should last a very long time, as long as you look after it of course. Don't abuse the mirror by washing too often. A mirror that looks slightly dirty will work fine. Wait til it's bad or has resiny looking deposits on. For example some trees give off horrid sticky resinous stuff. Lime trees are awful for that. When you have the mirror out, put a centre spot or a ring in it's centre. Makes collimation so much easier. In the first link, there's a explanation of how to do this. More examples will be probably somewhere on the web. Cheers, Andy.
  45. 1 point
    Hello, here is the latest update. I'm happy with how the pier came out, it's really stable and I think the stairs mounted to the pier on the first floor gives it a little extra stability. Telescope is mounted and there is a picture of one of the wheels holding the dome in place. //Ola
  46. 1 point
    Here's the standard-sized drawtube alongside the TAL original. Doesn't help much, I know. I probably bought it 10-12 years ago - I suspect from BC&F. You might also try Optical Vision; I know they used to stock lots of TAL accessories.
  47. 1 point
    I've put some pics of eyepiece adapters(both the std Tal 2M version for a yr 2000 scope and a 3 piece set) on my flickr pages http://www.flickr.com/photos/8986911@N08/ (click on the pics to bring up a bigger pic & explanations) showing how an older Tal could be uprated or if the original adapter was lost. Thought I'd post a link rather than clog up this thread with pics. Andy.
  48. 1 point
    Righto. That's good. Confirms with what Richard said about his. It'll probably be an M42x1(1 being the the pitch of the thread), which is the common Russian camera thread(but not so common for adapters available today. M42x0.75 or T2 is a much used thread). This means, in the future, if you wish to use other std 31.25mm eyepieces etc and have them fit securely, there is a way. Of course you can simply wrap a single layer of elec tape around their barrel and use the focuser as is, which will do the same job, just won't be as pretty. I have looked out a few adapters that would work and I'll take some pics. This is all optional of course and not strictly necessary. One thing I'd consider, is obtaining an 8mm eyepiece. That'll plug the magnification gap with your current ep's & barlow. It would give you 150x, which can sometimes be a more useful high mag power than the barlowed 25mm ep(192x), especially when the seeing is poor(ie: the air is very turbulent, causing high powers views to be washed out and mucky). Andy.
  49. 1 point
    Some of these were taken with a Skymax 150mm Mak. I sold it and have regretted it ever since.
  50. 1 point
    Choosing a CCD Camera Buying a CCD camera is not a particularly easy job. Several reasons exist for this. When browsing different manufacturers websites, a vast array of number and graphs can be thrown at you, which can be very confusing. Also, spending several thousand pounds, or the equivalent, is a task you don’t want to make a mistake on. In this we will go through some important factors to consider. The most important quantity is the Signal to Noise ratio, SNR or S/N. You want lots of Signal and low Noise. So we can break down our analysis in to two parts. What quantities maximise S and what minimise N. Signal Quantum Efficiency: Or QE for short. This number is the ratio of detected photons (light particles) to the total number. An ideal detector will detect all photons that hit it, and thus 1 (100%) is the ultimate limit. A high QE will help maximise S. However a high QE sensor can be expensive. Most amateur CCD’s are whats known as Frontside Illuminated. This is the standard technology, whereby light passes through silicon electrodes before interacting with the photosensitive region. The downside of this is a poor UV/Blue response (<400nm), however, most imaging is not conducted in this region, so a poor UV response is not a major deal. A typical front illumination CCD will have a peak QE of between 0.4-0.8 depending on the exact technology used to make the CCD. The range of response will be useful between 400nm-900nm typically. If one is imaging emission nebula, then a good QE (0.5 is a good guide) is important at the following wavelengths.....H_beta=486nm O[iII]=500.7nm Ha=656nm S[iI] 673nm. This range spans blue/green to deep red. If one is imaging galaxies or stars, then a wide range of response is also important A typical CCD will have a useful response between 400-900nm. There are two main types of CCD architecture employed today. Interline Transfer and Full Frame CCDs Interline transfer CCD’s have a vertical shift register between pixels, and this structure reduces the fill factor (the percentage area of the pixel useful for detecting photons). This reduces the QE, and the peak is around 0.5-0.6. The response at 656nm is around 30%. For this reason Interline Transfer CCD’s are cheaper, so are definitely worth considering. An example of a popular Interline CCD is the KAI 11002 or 4022 Full Frame CCD’s have a 100% fill factor, and offer the highest QE of any frontside device. The QE for the full frame KAF3200ME is 0.85. To summarise: A high QE will help maximise S. The range of which the CCD is responsive is a good thing for galaxies. A good QE at 656nm (Ha) is important. Interline CCD’s have a lower QE, and cost than a Full Frame sensor. Thats pretty much the only way to maximise S. Noise We want to keep the noise to a minimum. There is one noise source we cannot minimise through our choice of CCD or camera manufacturer.....source shot noise. This is a noise caused by the statistics of photon counting. However, the ideal noise performance of a CCD image, is shot noise limited. If your CCD gives you shot noise limited images thats a good thing. Read Noise This is the noise introduced when reading the CCD out. Camera manufacturers have some control over its value, by carefully optimising the CCD and readout electronics. Therefore, different manufacturers should be looked at when purchasing a CCD. Read noise is the lowest signal you can detect. In some sense, Read Noise is a good measure of low light performance. A value of 4 - 9e- is about typical. If you want to generate a good S/N with low signals, a low read noise is the way to do it. Summary: Low Read Noise is good Shot Noise and Fixed Pattern Noise shot noise from the source is unavoidable, but dark current is an avoidable form of shot noise. More later. Fixed pattern noise is not usually specified by manufacturers, and can be removed through the process of flat fielding. A value of around 0.5% is typical. Fixed pattern noise limits S/N, so it definitely needs removed. It is a problem encountered with high signal levels like planetary imaging or deep exposure of bright objects like M42 or M31. Dark Current. Even when in the dark, the silicon lattice will emit electrons randomly. This is called dark current. It is a quantity that is very temperature dependent. The colder a CCD operates the lower the dark current. Typically dark current (expressed usually in e-/pix/sec) halves for each 6C drop in temp. Most CCDs are offered with at least a ΔT of 30C...ie, a cooling of 30C from ambient. Several manufacturers offer cooling of ΔT=70C. This certainly inhibits the dark current. Dark current adds shot noise to an image, as well as dark fixed pattern noise. The more dark electrons are released during the exposure, the greater these quantities will be be. A value of <0.01e/pix/sec is a good number for imaging. 3e- of noise would be produced for a 15min exposure. An important feature also is set point cooling. This is the ability to operate the CCD at a fixed temperature irrespective of changing ambient temp. Dark subtraction using dark frames works best when the temp of the darks matches the temp of the lights. With set point, you can take darks during the day while at work etc, as long as the same temp can be reached as the night-time images. Summary: A good amount of cooling is advisable. Most CCD’s feature low dark currents when operated in the region of -30C Residual Bulk Image Some CCD types are prone to Residual Bulk Image, RBI. Red and Near IR photons interact near the substrate-epitaxial interface, where the generated electrons are prone to being trapped. These traps can become filled or partially filled during an exposure. Then when taking dark frames, these electrons become untrapped via their thermal energy, and may be collected by the pixels, and registered as additional, unwanted dark noise. These traps are also temperature sensitive, and so cooling the sensor will limit the amount that get released per exposure. The method used to control RBI is to flood the sensor with NIR light, flush the CCD before exposure, then take an image as normal. The NIR flood fills these traps, and stops them collecting signal electrons during the integration. With the sensor run cold, these electrons have a typical ‘trap lifetime’ of several hours (maybe more), so very few leak out during the acquisition of new light frames or dark frames. You know you have RBI if there is a pattern of signal in your darks that closely matches your light frames....eg, the moon can be seen in your darks! Some sensors exhibit RBI. These include the KAF full frame range, and those featuring LAB (lateral antiblooming).... for example the KAF3200, KAF 6303, KAF16803. Some manufacturers don’t currently support this flood flush integrate technique, so thats worth checking. Summary: If a sensor is liable to RBI, deep cooling and flood flush integrate techniques are very advantageous We have discussed aspects to maximise signal generation (QE) and minimise noise contributions (low Read noise, deep cooling, RBI management). A camera incorporating all these features will deliver a high S/N. However, there are other quantities specified that are important Other Factors Full well: The number of electrons a pixel can hold before blooming or non-linearity sets in is called Full Well Capacity. Full frame sensors, the KAF line from Kodak, feature higher full well than a similar sized pixel in an interline sensor KAI line. The size of a pixel primarily affects the full well capacity. Smaller pixels hold less. A 5μm pixel can hold around 25,000e- (KAF8300) whereas a 12μm hold around 110,000e- (KAF9000). When the sensor is limited only by shot noise, the signal to noise ratio, S/N is given by the square root of signal. So a higher full well camera is capable of deliver higher S/N. However, the typical astroimage of a deep sky object will not be anywhere near full well. A large full well would be important when imaging very bright objects, like the moon or planets, but is of limited use in deepsky imaging. What is very important however, is the dynamic range. Dynamic Range: This is the ratio of maximum resolvable signal to minimum resolvable signal. This is equal to Full Well/Read Noise. The dynamic range is the CCD’s ability to record both bright and faint signals. If two parts of an object have an intensity ratio of greater than the dynamic range, then the bright part will saturate the pixel before the faint area has been detected. Many objects exhibit a wide dynamic range, for example the core of the Andromeda galaxy is many times brighter than that of the outer spiral arms. Given a typical well depth of 40,000e- and a typical 8e- read noise, a value of 5000 levels is typical. CCD’s can be found with a DR of 2000-10,000 however. It is conventional to express the DR in decibel, dB, units. Use the formula DR(dB)= 20*log(FW/read noise) Summary: A wide dynamic range is advantageous for astroimaging, and it is probably more important than full well capacity. A good dynamic range can be achieved through a decent full well and lower read noise. A lower read noise also gives good low light performance. Antiblooming: When a CCD pixel collects more charge than it can hold, the electrons spill out and create a blooming spike, which can cover important parts off an object and don’t look particularly nice. CCD sensor manufacturers can incorporate structures to channel excess charge to ground, thus avoiding charge spill over. However the incorporation of these structures reduces QE, fill factor and full well capacity. However an antiblooming CCD can take very deep images without blooming, so this feature can be an advantage. The spikes can be repaired in photoshop, but the image under the spike is lost forever, and the repairing of spikes can take time. Using narrowband filters, star light is heavily attenuated, whilst signal from the nebula is not. Blooming is far less likely to occur and so a non-antiblooming camera may be superior for this application. However, blooming may still occur so individual preferences will be the overriding factor on choice. Colour vs Mono: CCD’s are inherently monochrome devices. They don’t record colour. To make a colour image with a mono camera requires filters to be placed in front of the sensor, and the image then assigned a particular colour in post processing. For a typical RGB image 3 exposures are required per colour image. This can be time consuming. So CCD sensor manufacturers can lay an array of RGB filters over the pixels themselves. In a grid of 4 pixels, the typical layout is RGGB. One pixel corresponds to one colour, so a colour array will 25% of the full resolution for B and R, and 50% resolution for G. A colour CCD will produce a colour picture on every exposure . However the colour CCD has a lower QE than its mono equivalent, and is not as versatile, in that for narrowband imaging, and general deepsky imaging, a mono CCD is a better choice. The choice is between having to take 3 sets of images to generate a colour image and QE loss with a colour CCD. Pixel Size: Pixel size affects the resolution of the image. At a given focal length, a smaller pixel with produce a higher resolution. The resolution in arcseconds per pixel is given by: resolution=206*(p(um))/(f(mm)) P is the pixel size in microns, and f is the focal length in mm. Small pixels, whilst delivering high resolution, will typically have a lower well depth, reducing dynamic range. They will also be more subject to atmospheric seeing. For most locations, a value of 1”/pix will be about the highest useable resolution. The focal length to provide this is f=206*p(um). If your imaging telescope has a higher focal length, you may want to consider a larger pixel. A large pixel, will have better dynamic range, and full well, but a reduced resolution. It could be the case that the image looks quite pixellated. A value of 1.5-2”/pix is quite good, and the best of both large and small pixels can be achieved. There is definitely a trade-off with regards to pixel size. Sensor Size: The size of the CCD only determines how much sky you image at one time. A large CCD might be required when working at very long focal lengths. A small CCD may be all thats required when imaging say with camera lens and small telescopes. The more area a CCD takes up on the Silicon wafer, the higher the cost. However, technology employed means that some small CCD’s are more expensive than large ones. An example would be the very sensitive KAF3200ME. It is much smaller than the KAI11002, yet the KAF3200 is considerably more expensive. Small isn’t always cheap! Conclusion There is always a trade off with picking a CCD for your needs. You need to figure out what you want. Some things may be important to you, others not so much. I would look at quantities like QE, read noise, level of cooling, RBI management, set point cooling, dynamic range. I advise you scout around the various camera manufacturers, look at the parameters, and see if any vary from manufacturer to manufacturer. Read noise and cooling typically vary a bit between manufacturers. Thanks for taking the time to read this. Paul Kent 24/10/09 Choosing a CCD Camera.pdf
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