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westmarch

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Everything posted by westmarch

  1. Hi there, welcome to the forum. John
  2. Contact your local authority and ask for a shield to be put on the street lamp. If necessary, tell them it is intruding into a bedroom. I had one fitted within the week. Alternatively, make a local shield - a tarp nailed between two wooden uprights - you put it up when you are observing. Finally, get a long hood to wear - a bit like this. John
  3. Hi Michael, I suspect you and Peter are correct, you will have to correct the height of the south bearing. If the platform is level, and you wish to correct for a more Northerly latitude, you will need to depress the southern bearing height. If you start by incrementally raising the northern bearings with plywood packers, you will get an idea of the amount of South bearing shimming needed. Alternatively, you can just incorporate the Northern bearing packers into your set up. Just remember your design is optimised for a different latitude, it will always be somewhat of a comprise and the bigger the difference in latitude, the bigger the compromise John
  4. Superb session last night - cloudless, slight wind to keep off the dew and moonless - a perfect galaxy session. Went up to the N York Moors at Sutton Bank and set up the 10” dob by 9pm. When star hopping, I tend to use a 40mm plossl as a seeker and found that a 15mm Explore Scientific EP consistently gave me the best resolution and contrast in this Bortle 4 sky. There were a few DSOs I specifically wanted to do having missed out on previous sessions. Antennae Galaxies NGC 4038 and 4039 - by the time I had set up these were frustratingly just edging down into the tree line. M61 - struggled with this but it was entering the Vale of York light pollution arc. Picked out in averted vision. NGC 4526 - lovely oval galaxy nicely framed in a crux of surrounding stars. M85 - Nice elliptical galaxy, easily found with the bonus of adjacent NGC 4394 popping into view in averted vision. M64 - oval galaxy with dark irregular patches - intriguing. I spent a fair bit of time trying to tease out detail. M49 - brightly nucleated oval galaxy. NGC 4565 - classic edge on, needle profile with central bulge and long extended arms. I tried and failed on the Whale Galaxy NGC 4631 - this was towards the end of the session and was almost vertically above in a relatively star free zone. Dobs are not the easiest to manoeuvre in this position and I sometimes felt that I was in a lovers embrace with the OTA as I moved from RACI to EP. As I was packing up, I had a chat with a chap who had been taking light readings for the National Park. We both bemoaned the continued presence of a stud stable that had erected all-night floodlights, on gantries, immediately adjacent to the park to protect their racehorses from theft. Despite the Sutton Bank site having dark sky status, there is apparently nothing to prevent this! 🤬 That apart, a very enjoyable night. John
  5. I’ve had a 10” Dob for a number of years and it is very stable. It will sit on most surfaces and, as Michael says, the short studs under the base will sink into soft ground and add stabiity. I have put it on a tarp if the ground is muddy. John
  6. It’s been a while since I visited Reiner’s website - it is by far the best resource on the web for self builders. John
  7. Hi there, your plans for the 12” Dob base sound right to me but my advice to Frank stands: this set of instructions works for up to 10” Dobs, beyond that you need to be careful that your centre of gravity, on full tilt, doesn’t end up outside the base. If it does, you may have to move the tilt limiting bolts inward on the arcs - reducing the travel. For setting circles, the RA is fine but declination is dependent on your telescope base being level. That means you have to put the platform in the mid. position and you half the possible travel when you switch on the motor. I have setting circles on mine but find them a bit of a faff and rarely use them; relying on Sky Safari and star hopping instead. Good luck with the build. John
  8. Someone tell me, what’s IPA, presumably not India Pale Ale. 🤔 John
  9. It is so easy to do in the dark! Pointing the south pole of the platform north is another one I have done - that’s a real hassle to correct! 🙄 John
  10. What with global warming, is it not ironic that we have created our own twilight? John
  11. Hi there and welcome to the site, dew is a perennial problem in our green and pleasant land. Some nights are especially prone to it and the forecast on Clear Outside is a good guide to it. You can find this in the resources menu at the top of the website. You want to cool your scope to reduce heat currents within the scope but when the scope becomes colder than the moisture laden air, dew starts to condense on the scope. In Newtonian scopes, the primary mirror is usually protected by the column of air trapped within the tube it is often the exposed secondary mirror which gets colder first and mists up. The finder scope is also relatively exposed and will cool quickly. There are a few things you can do: 1. When you leave your scope to cool, point it horizontally. Pointing the mirrors at the deep cold of space is the quickest way to radiate off heat from the mirrors. 2. Fit a dew shield. This can be as simple as a foam camping mat around the end of the scope. If you do a search on dew shields you will see some examples. This extends the column of stable air beyond the secondary mirror and slows heat loss. 3. You can fit dew heaters - these are electrical heaters which maintain the temperature of the scope a few degrees above dew point but don’t generate distorting heat currents. These can also be fitted to finder scopes. 4. Keep eyepieces in your pocket when not in use. Since these are some of the most exposed pieces of your optical train, this will keep them warm and help prevent misting. 5. Use a portable hair dryer on cool setting. This can evaporate dew but its effect is relatively short lived. Hope the above helps and don’t become discouraged. Not all nights are dew magnets. John
  12. Superb improvisation. I’ve got a lump hammer bolted to the end of my dob - whatever works! John
  13. Hi there, Is this not what you are after? https://uk.rs-online.com/web/p/power-cords/9135111?cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Cables_%26_Wires_Whoop-_-Power+Cords_Whoop-_-9135111&matchtype=&pla-347726324301&cq_src=google_ads&cq_cmp=9771206761&cq_term=&cq_plac=&cq_net=g&cq_plt=gp&gclid=CjwKCAiA2L-dBhACEiwAu8Q9YBHhOiYFGJD-XKcjKvMZRjr-XDnoMHGiFBM8HHVMgS1R6vMjAHFv8BoCY1IQAvD_BwE&gclsrc=aw.ds You can then terminate it with whatever plug your power tank socket requires. John
  14. You know the satisfaction (or in AP, perhaps the lack of frustration) you get when when every little electronic gizmo and software enhancement works the way it should? Finding your target by star hopping or teasing out the observational detail, during a moment of perfect seeing, is similar. It is like turning up an interesting object with a metal detector, or an angler getting a bite. Sometimes the journey is as interesting as the destination. John
  15. Hi, there is a thread (no pun intended) here on bolts and where to get them: hope that helps John
  16. Hi Peter, hadn’t thought of a filter but might try it when we get another clear night. If I’m honest, Mars wasn’t high enough really but the clouds were rolling in so I chanced my arm. I could certainly benefit from another pair of eyes! Probably too late now for Santa’s list. Have a good Xmas. 🎅 John
  17. Just Wow! That is one of the most elegantly designed and constructed rigs I have seen. Thanks so much for sharing. John
  18. Came across this compendium of stunning images on CNN for anyone who has missed it. https://edition.cnn.com/interactive/2022/12/world/best-space-photos-2022/ John
  19. The weather forecast showed a clear spell this evening between 17:00 and 18:30 and a chance to get in some planetary observation. My southern aspect sits directly under a streetlight, so normally I never take the dob out there. I read a thread recently where @vlaiv advocated avoiding dark adaptation with bright planets and using your more densely packed retinal cone receptors to get more detail and, perhaps, some colour vision. I think this and some other factors helped me got some of my most detailed views of Jupiter tonight. Using BST Starguider EPs, I found x180 was a bit mushy but at x140 maximised contrast: the GRS was clearly visible and I was able to distinguish S Polar Region, S and N Equatorial Belts as well as the N Temperate Belt. Mars was subtle, as always, but Syrtis Major Planum and Meridiani Planum were easily distinguishable but I could not pick out the Polar Ice Cap. Several other things helped, IMHO: 1. Good seeing and transparency. 2. Relatively high visual altitude 3. Wind of 10mph - normally this a problem but I think it served to disperse heat shimmer rising from rooftops under the field of view. Also, by causing an occasional tremor in the FOV, it improved perceptions of detail - a bit like the effect you get when you are struggling to perceive a DSO and the movement from a slight tap on the scope makes it pop into view. 4. A stable position of the target in the field of view. In this case, an equatorial platform but any equatorial mount drive allows you the time to exploit moments of good seeing and tease out detail without constantly having to reacquire the target. 5. Aperture - this seems to be controversial for planets but having looked through a number of refractors and SCTs, I am convinced that a large aperture scope enhances detail even in bright objects. All in all, a very satisfying opportunity snatched before the clouds rolled in. John
  20. You may find these links helpful. https://www.blackwaterskies.co.uk/2013/05/a-cheap-multi-channel-dew-heater-controller/ https://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater-bands/ John
  21. I love restoration projects. Best of Luck! John
  22. If you can get your Dob away from light pollution, it is the equivalent of having 2-4 inches extra aperture. If you have access to a dark sky area, a Dob that you can transport easily ticks all the boxes. For this, my advice would be something that you can comfortably lift and fit in your car. I find a 10 inch is the sweet spot and a truss dob just makes things easier. John
  23. Mods, this might get better advice if it was moved to AP section. John
  24. Terry, I think you have to temper your expectations. You are beyond the lower latitude that this design is optimised for but that does not mean it is not functional. 1. EQ Platforms are not going to give you EQ6 level tracking. 2. If you are looking at DSOs, you are never going to be using high mag so a bit of drift in a wide FOV is not a game changer. If this is not enough for you then try the following: 3. Shim the southern pivot. (a) Your bottom platform should be level. (b) Get a digital inclinometer/protactor. Only costs about $£10. Put it on the top platform and zero it. (c) Incline the southern end of your upper platform with wood packers until your inclinometer shows a 4 degree elevation. (d) Measure the distance between the upper surface of the bottom platform and the lower surface of the top platform. That is your target elevation for the southern pivot. (e) Get a longer bolt and put it through the southern pivot bolt hole. Now mark it at the measurement that you made in (d). Cut it and round off the end. (f) substitute it for your original bolt. If you started off with segments designed for the minimum latitude that Reiner Vogel specified (46 degrees), then your 4 degree shim will have converted it to a 42 degree platform. This, combined with Michael’s suggestion of trimming the speed, should give you a more stable target acquisition. I can’t however emphasise enough! Check that you are happy with the stability of this setup at full tilt before committing your precious Dob to it, unsupported. Good Luck! John
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