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Jim-a

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Everything posted by Jim-a

  1. Another nice session last night. On BigMakStutov's recommendation I hunted down the blinking planetary. It took a while of scanning the sky roughly around where the telrad pointed me with a 25mm before I noticed something that was not quite star-like. Upping it to 9mm and there it was... blinking. Looking at the star next to it the nebula 'halo' would pop into view, then as I looked directly at it it would quickly fade (although not completely - I could still see the shape of it, but very much dimmer than looking directly). Really good demonstration of how effective averted vision is. Quickly took in the globs M56 & M71, then I tried for the Veil - but no luck - don't know if I need a much wider field of view, or if the LP where I am is reducing the contrast too much - I'm assuming I was pointing in the right place as there's a vary obvious star that should be slap bang in the middle of it. After failing on the veil I then had success with M33 in triangulum. Last time I was out I tried to find it, but wasn't able to. This time I persevered and eventually saw a very feint smudge moving as I wobbled the scope around. Couldn't really see any structure and if what I found was M33 then I can see why I missed it the last time around. Guessing I really need to put the scope in the car and head out to somewhere darker soon. Next up was M74, but didn't manage to find it - and by that time Jupiter was distracting me by shining out over next doors roof, so I finished up with a bit of planet gazing before packing up.
  2. Thanks Moonshane - The thread on your platform build has been a real help in getting my head around the options. Hopefully I can pick your brain at some point if need be! The jig method for making the VNS segments was lifted from this French site (diagrams helpful though) and this guy who's set-up puts my lashed together sanding jig to shame.
  3. I thought I'd start this thread to document the equatorial platform I've started building. Hopefully it will help anyone thinking about building one in the future - I'll try and note down any "wish I hadn't done that" moments / mistakes / successes etc as I go along. Feel free to chip in comments / questions or whatever. After a lot of reading around I decided to build a platform with a vertical north sector and a circular southern sector. I seriously thought about going with a single south bearing, but I think that would have meant the platform would stick out from under the scope and I wasn't so keen on that. I also decided I wouldn't try to replace the azimuth part of the existing base with the top of the platform I'm making - I'm just going to put the whole scope on the platform - I reckon that will give me a bit of wiggle room, and will mean that the measurements don't need to be as precise. I'm planning to drive it with a bearing on the north sector directly attached via gears to a motor. Other than that I've decided not to think too much about the drive until the main wooden bits are all constructed. I played around with a lot of the spreadsheets out there (the yahoo eqplatform group is a good source) - but found that nothing really beat getting a big bit of paper out and drawing it out myself. One of the key measurements you need is the centre of gravity of your scope setup - theres a really good explanation of how to do that here http://www.equatorial-platforms-uk.co.uk/home/cofg-or-centre-of-mass-calc . I was really surprised that the c.o.g. for my lightbridge was only 37cm - but the base is pretty hefty. The first thing I did was to cut a custom 'set square' type thing out of MDF with my 51.5 degree latitude - really glad I did, lots of the angles you end up cutting can be checked against it. My various bits of paper and scribbled maths cam out with a south segment radius of 12cm - so I glued a couple of bits of 12mm exterior ply together and cut a rough version with a jigsaw then finished it off with a disk sander attachment I cut supports for the segment using the set-square and screwed them on (eventually I will glue and screw everything solidly, but for now I'm just using a few screws so that everything can be undone and re-done when I get things wrong) With the south segment attached to the top board of the platform I attached two pieces of glued together ply which will become the north segments. I'll cut the board to shape later - but for now I'm leaving it as is so that I still have a chance to move things around if need be To shape the north segments I made a jig to rotate the platform around its axis - again the set-square came in handy for making sure the angle was right. In the picture you can see a piece of wood attached to the south segment with a hinge. With a second piece of wood and hinge connected to the other end of the platform I screwed it to the shed door making sure that it was properly vertical To get a rough idea of the outline of the segments I used a piece of wood clamped to a workbench at the correct angle, with a hole drilled through it to take a pen. Then by rotating the platform and jig about the door frame I could trace a line where the cut would eventually be. After unscrewing the segments, cutting them roughly with a jigsaw and screwing them on again I set up the drill with the sanding disk at the right angle for finishing the segments. Lots of spare bits of wood and all the clamps I could lay my hands on seemed to do the trick. Then it was a case of rotating the jig against the sander. It took quite a long time to take off all the excess wood - but the finish looks really smooth. Thats as far as I got this weekend. Any questions / comments / thoughts / tips / advice - all gratefully receieved.
  4. Seems I wasnt imagining the blue then Stu - I havent seen the blinking planetary yet - so will put it on the list. I started the platform this weekend - I've been taking pictures and I'll start documenting the build in the DIY section of the forum - no idea how long it will take... probably depends on how many problems I hit on the way.
  5. Bit of a whoops last night - and a lesson learned. The screws holding the hinge section at the top of the chair split the wood and I went sailing backwards - luckily I landed OK, fell away from the scope and its not like anyone was there to see!! But it does serve me right for bragging that I hadn't fallen off it yet in my original post!! I guess that top hinge part of the chair must take be under quite a bit of force as you move around on the chair - so one for todays to-do list is to replace the top block (that the hinge was screwed into) with something more substantial using a harder wood and beefier, longer screws
  6. Had a really enjoyable night out last night. I tried to avoid my usual favourites (although I did sit and stare at andromeda for a good 15 minutes) and find some new things.... M15 in Pegasus - nice Globular cluster, resolving granularity and stars pretty much to the center. M38 in Auriga - was just clearing the roofs of the houses, but a got a nice view of this open cluster. M33 in Triangulum - completely alluded me - had a good old scan around but no luck - and eventually gave up and moved on. The Blue Snowball - was a nice and round little ball with slightly fuzzy edges. I thought I could detect a bit of a blue-ish tinge to it, but not sure whether that was just my brain telling me its blue because thats in the name, or whether I actually saw it. M76 - The litte dumbell - was faint at first, but with a good long stare and a spot of averted vision I could see an almost rectangular shape. Then to round things off Jupiter had popped out over the neighbours roof. I'd been looking forward to this... I've only seen Jupiter in a 4" reflector before and last night was the first time I got to look at it in the 12" Lightbridge. Even though the seeing wasn't great and it was low in the sky over the rooftops it was stunning. I could clearly see the main banding and with 20 mins of looking start making out some subtle variations in colours across the planet. It seemed best last night using a 12mm eyepiece (so 125x mag) - though I'm looking forward to completing my equatorial platform build as I find the constant dob-nudge pretty distracting. All in all a good night out (with the exception of a slight chair problem which I'll mention in the DIY forum). Really looking forward to Jupiter getting higher in the sky earlier as the months go on and was pleased to bag some new DSO's.
  7. richard - I got it from Scopes & skies - I spoke to them on the phone and they said it looked like other ones they had (although I still cant see that it could be right - it works ok - but would be so much better if the whole of the target was illuminated through the hole) - they said they would get AE to drop me a mail - I never heard from them.
  8. I'm thinking about building an Equatorial Platform for my 12" Lightbridge. So far I have decided to go for a Vertical North Segment design. Whilst its going to mean a more difficult surface to shape, I'm guessing that the benefits of being able to mount the north rollers horizontally will make it worth it. I've got some initial questions that hopefully someone can point me in the right direction on... 1. One thing I can't work out from reading the various posts on here and the ones on the yahoo eqplatform group is where the baseline of the cone should intersect the south segment... I've drawn what I think is probably right here (greatly exaggerating the width of the segments)... .. but would be massively grateful if anyone who has built one can confirm that I'm right.. or put me straight. 2. From a quick search it seems that there are about a billion different types of bearings available... has anyone got any recommendations? 3. Does anyone know where the Centre of Gravity of a 12" Lightbridge is - I'm assuming its an inch or two below the center of the elevation pivot - but I don't know how critical it is to get it spot on. 4. I'm planning on using a slow rev motor (possibly geared down) with a PWM speed controller - and directly driving the north segment with it (as opposed to a threaded rod type drive, which seems a bit fiddly to me) - does anyone have any tips there? Sorry... thats a lot of questions I know - any help gratefully received.
  9. got the chance to try it out last night - makes a massive difference... before, using the crouch-at-the-eyepiece technique, I'd find that I had to keep shifting position to stay comfortable (and would often accidentally look at a neighbours light or something as i moved away from the eyepiece and ruin my dark adaptation). Last night I was able to spend a lot longer looking continuously at each object - being able to get the height of the seat just right for the angle of scope makes it pretty simple to get a comfortable position. The only slight downside is that the wide front 'foot' tends to nudge right up against the base of the dob when the seat is at the eyepiece position - if the foot was at the back this would solve that problem, but I suspect that it would make the balance much more unstable (and increase the falling-off likelihood), so for now I'll live with it.
  10. Thanks guys... here's an Inside-of-the-seat pic for Barry... .. hope that helps
  11. Today, with a bit of time on my hands, I knocked up this adjustable observing chair. A couple of cut-up old recycled boards that I discovered in the loft make up most of it, with other odds and ends of scrap wood and a couple of old hinges that were in the shed - total cost £0.00. The design is based on some of the chairs I've seen on here (thanks for the inspiration everyone) and the top height is just right for getting the kids eyes at vertical-dob-eyepiece-level. Seems fairly sturdy so far... well I haven't managed to fall off yet!!
  12. This zoomable map is helpful for finding dark sites http://www.avex-asso.org/dossiers/pl/uk/index.html
  13. Theres a park very near my house that hosts outdoor film screenings. Last night as I was out in the back garden looking at M13 the wind must have changed direction slightly and I could hear the soundtrack to 2001 A Space Odyssey - crystal clear. Intently staring into the eyepiece at a spectacular globular cluster while thinking about the theme of the film whose music and dialogue I could clearly hear wafting over from the park made for a pretty good combination ! Hadn't really thought before how sound can enhance what is basically a visual hobby - anyone else listen to music or other things while observing?
  14. not sure what the out-of-the-box, non-bobs-knobs are like as these had been fitted by the previous owner - perhaps someone else can comment?
  15. I've read lots of posts on here outlining various modifications people have made to their dobsonians. I recently bought a second hand 12" Lightbridge - and its only taken just over a week before the mod-bug bit. When moving the lightbridge about, the only thing to rest the bottom part of the OTA on when taking it off its base are the collimation knobs. Even though it doesn't sit on these for very long (just the time it takes to lift the OTA off, move the base, then put the OTA back) it didn't seem very sensible to rest the whole weight of the mirror and tube on the knobs (even if they are Bob's ! ). A visit to my local hardware shop and £6 later I had 3 rubber door stops and an assortment of washers, nuts and bolts. Disassembling the scope was pretty straightforward, then it was just a case of drilling three holes, bolting in the new feet and putting it all back together again. The lower OTA now sits happily on its new feet, with a centimetre or so's clearance between the ground and the collimation knobs. Now thinking about the next mod - probably something to help balance for different eyepieces etc. Any other suggestions?
  16. I've just started using a telrad and so far its been a good experience (even under moderately LP suburban skies). If you are going to star hop with a finder scope then try printing maps out from Stellarium. There are various setting you can tweak which, with a bit of experimentation, should get you a picture which matches what you can see in your finder.
  17. I've just bought a Cheshire collimator and think that either I've got a dud - or if its not a dud then theres a bit of a design flaw in it - or if its not a design flaw, its a flaw in my understanding (quite possible) of how the thing works. The position of the window in relation to the diagonal 'target' is such that the diagonal is not fully illuminated by light coming into the window - the result is that you get a non-circular target to work with - probably not explained very well but I've attached a couple of pics to show what I mean. Be grateful if someone who knows more than me could let me know if the problem is me, the design, or the manufacture. Ta v. much
  18. My first time for M31 last night as well. Got it in bins first & then through the scope. Couldn't see it with naked eye though - but am assuming that the fact it was only just clearing a neighbours roof, and they had some lights on which were in my field of view with the naked eye, but not with the bins or scope was making it more difficult.
  19. I tend to use meteoblue and 7timer as have already been posted, but then nothing beats http://www.sat24.com/en/gb for looking at which way the gaps in the clouds are travelling on the day.
  20. Theres lots you should see in your scope - although at the moment with the lighter evenings its not the best time to look for DSO's. To give you an idea, things I've seen so far in a 4" include... M13 - globular cluster in Hercules M81/82 - Bodes galaxies M57 - the ring nebula in Lyra M51 - the whirlpool (although that was under pretty dark skies - not my Reading back garden) Each of these benefits from letting your eyesight fully adapt to the dark - and also using averted vision (for example under my LP skies, with my scope, you can see the ring structure of M57 if you dont look directly at it - otherwise its just a faint fuzzy blob). Hope that helps
  21. Thanks v. much for the help guys. Its now a choice between the Helios Fieldmasters (based on tetenterre's excellent site) and the Olympus DPS1's. Do I stick with the original £50 budget and go for the Fieldmasters...? or go to £60 for the Olympus ...? but then why not £70....? or £80 ... or £100 ? - arrrggghhhh - I'm beginning to realise that in this astro game there is always a slightly better option at a slightly higher price... got to draw the line somewhere
  22. click on your name in top right hand corner of screen - select 'My Settings' - then on the left hand side of the page you'll see "Signature' in the list - click on that and you are there
  23. Hi I want to get some bins for taking on holiday this summer (if you can call it that) and for general observing / keep-in-the-car-just-in-case. Preferably sub £50 (as I'm also planning on buying a dob before it starts getting darker and don't want to break the bank) Would be massively grateful for any opinions / experiences - good/bad with any of the following shortlist. Helios Fieldmaster - 10x50 - £48 ... http://www.harrisontelescopes.co.uk/acatalog/Helios_Fieldmaster_10x50_Binocular.html Strathspey - 10x50 - £45 (by the time you add p&p + vat) ... http://www.strathspey.co.uk/shop/full.php?q=1118253053 Praktica - 8x56 - £45 ... http://www.amazon.co.uk/Praktica-B00354-Diana-8x56-Binoculars/dp/B0015U58QA ...or is it worth pushing the budget another £10 for... Olympus DPS1 10x50 - £58 ... http://www.amazon.co.uk/dp/B0000AKGX3/ref=asc_df_B0000AKGX38346598?smid=A3IGCAX4OXJ32U&tag=pr-syn91-21&linkCode=asn&creative=22218&creativeASIN=B0000AKGX3&ascsubtag=a1400617925eba4c6270e2ce14e6c4fc Thanks everyone in advance Jim
  24. its awesome (in the proper meaning of the word) when you start looking up isn't it - I still cant believe I let myself get to the age of 41 before I saw Saturn with my own eyes. Other objects that I've found to be good 'newbie targets' are... Albireo - a lovely blue/red double star - below vega/lyra, M13 in hercules - which was my first (and to date only) globular cluster, the ring nebula - and bodes galaxies... they are all (just about) visible in my little 4" reflector - and even though the the views are faint - the fact that those photons have travelled un-imaginable distances before they hit my retina just adds to the wonder. Enjoy exploring!!
  25. fantastic detailed image - you can almost see the guys waving out of the cupola window
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