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jambouk

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  1. jambouk
    Someone asked me why glass was used to make telescope mirrors, especially massive telescopes. “It would be much lighter if they could just put a reflective aluminium layer on a lighter material!” “So why not make massive mirrors out of carbon fibre, shaped and buffed to a high degree and then coat that with a reflective surface? Or other materials?” The only thing I can think about is the smoothness of the grind, and the thermal stability of a massive chunk of glass, but these may well not be the reasons. Thanks for any help. James
  2. jambouk
    It is a bit noisy... but was running at 12V when only meant to run at 4.5V; need to find a suitable power source before something burns out...
  3. jambouk
    Modifications needed, but it works REALLY well! Thank you all. James IMG_1529.MOV
  4. jambouk
    Thanks both. The LightGrapher thing is good; it just took time to work out how to get it to run on my laptop, I can only get it to run with FireFox for the moment and only with the inbuilt camera on the laptop, not another one via USB, but will try again tomorrow. The limb darkening thing is interesting and I'd not thought about it before, though actually I think I recall someone talking about this at a meeting when exoplanet detection was all the rage. For the simple model I need, I don't think it is necessary to factor this in, but maybe worth mentioning for the more advanced members of the audience. I also recall from a meeting where an academic was showing transit traces, that the dips in light intensity during a transit were not symmetrical; the onset of the dip had a different morphology to the offset of it. I went up and asked him afterwards and he explained why, but I've totally forgotten what he said...! James
  5. jambouk
    My DIY mate thinks this will all be much easier with an Arduino or Pi. He sent me this link and he is going to make the detection and display parts of the kit: https://www.instructables.com/id/Plotting-real-time-data-from-Arduino-using-Python-/ Thanks for the comments. James
  6. jambouk
    We are going to try a light dependent resister in a cardboard tube and point it towards the star, and send the feed to the oscilloscope...
  7. jambouk
    Thanks. I was thinking of using a telephoto lens anyway, 70-300. The other option I thought was to just run canon utilities on the laptop with live view, and then make a suction cup to stick onto the screen with a light dependant resister inside and attach that with some simple circuitary with the help of a friend, to a small oscilloscope...
  8. jambouk
    We are running a session at my local society on transits and occultations. One station will focus on exoplanet transits, and we'd like to build a very simple model to demonstrate this. We have a star (light source) and an orbiting "planet" but I need to work out how to detect the changes in light intensity and display this on a laptop, like a classical transit photometry trace below (taken from https://heasarc.gsfc.nasa.gov/docs/tess/primary-science.html). Is there a way to take a feed from a DSLR through the USB output to do this, else I could get an adapter for my ZWO and put an EOS lens on the front of that. I really do want a light intensity vs time trace in real time on the laptop. This model will be run in a darkened room. Thanks for any comments. James
  9. jambouk
    Nice. Is upgrading the power socket on the future list of jobs? Something with a screw-type connection, like the one on the newer Skywatcher mounts - nothing worse than a power disconnection midway through a session.
  10. jambouk
    A very good day at the FAS Convention at the Institute of Astronomy yesterday, some great talks. My favourite was by Richard Ghail on "New insights from our closest Earth-sized exoplant: Venus." Fascinating content and excellent delivery. I'm not on the FAS committee, but they are hunting for a paper copy of the FAS Newsletter #114 (2018) to send to the British Library. If anyone has an original printed copy and happy to give it up, please contact FAS. James
  11. jambouk
    Intermittent issue seems odd. Make sure it is all dry inside. Can you borrow a handset from someone else and try that and their cable, that will help narrow it down. James
  12. jambouk
    Looks really lovely. Do you have any metrics on how the mods have altered performance? Backlash, periodic error etc? James
  13. jambouk
    With such short exposures, it is easy to take plenty with different settings and see what works best. shutter speed: 5 to 30 seconds and see what works iso: 1600 or so f/: stopped down two stops from maximum focus: use live view and zoom in to get something bright as small as possible.
  14. jambouk
    Defo go through the instruction manual page by page, it’s very good and it covers everything you’ll need to know.
  15. jambouk
    If the scope and all accessories are very light, then I’ve not bothered with a counter weight which seems fine for visual work.
  16. jambouk
    1. It sounds like the polar scope LED is too bright; on the handset go to utilities and polar scope LED or whatever it is called and make it less bright. 2. It sounds like you need to focus the polar scope. Rotate the bit you look through and you’ll see the focus changes. It will fall out if you unscrew it too much but that isn’t a problem, just don’t let it drop and smash it. The actual bit of glass with the circle engraved/printed on it is slightly further up the tube, so even if the eye piece bit falls out, you won’t have to realign the reticle.
  17. jambouk
    I did experiments with lay and long some years ago to prove they are in essence unimportant:
  18. jambouk
    I don’t think a handset firmware update will help - but maybe worth a try. I suspect you can’t do a motor controller update if it can’t communicate with the motors. Do you have access to local astronomers in a club to call on help for? James
  19. jambouk
    At the end of the three star alignment, does it say alignment successful or alignment failed? Inputting incorrect lat and long won’t cause this problem. James
  20. jambouk
    The common causes of this error message are: Leads put in wrong place by user. Poor connection with communication leads. Lead failure. Mount board fried. Incomplete firmware update of motor controllers.
  21. jambouk
    Sitting down and spending several hours reading through the manual is well worth the time. Also plug the handset in to the mount and sit down next to it (in doors in the day time in the warm) and just play about with it, you'll learn so much that way.
  22. jambouk
    Yes it is a tedious job. Nicely avoided this time, we’ll done!
  23. jambouk
    I transport my mount head in a small suitcase on wheels I got from the charity shop and pad it out with an old duvet cover - doesn’t look that impressive inside but it does the job. You could get foam and fill a larger suitcase on wheels and cut out the alt-az configuration yourself from foam, or just make a nest for it out of old duvet covers... if you want to transport it further than just in the car, you’d better get a more protective and robust setup; I suspect this will be £100-200... https://www.shop4cases.co.uk/product_list.asp?CatID=187
  24. jambouk
    Thanks both. We are going to do another evening on internet resources, so will save those for another day. The TA is a good idea and worth a mention. Thanks.
  25. jambouk
    I'm giving a talk to my local society on the various astronomy clubs and societies in the local area, and at the national level. What other national groups I have missed out: Society for Popular Astronomy Society for the History of Astronomy British Interplanetary Society Federation of Astronomical Societies Royal Astronomical Society Webb Deep-Sky Society William Herschel Society British Astronomical Association Thanks for any other suggestions. James
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