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About jambouk

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    Red Dwarf

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  1. Thanks. What would be the minimum angular diameter a micrometer on a massive scope with excellent seeing could realistically measure then? I've converted your millionth of a degree into 3.6 milliarcseconds which is pretty amazing!
  2. I've been reading that lunar occultations of planets and other moons in our solar system was used in the 1960s and 1970s to measure the angular diameter of the moons of Saturn and Jupiter. But I wonder why not just use a micrometer?? Presumabely atmospheric seeing would impact on both methods equally, but using a micrometer would not require a lunar occultation event to be occuring. Grateful for any thoughts. James
  3. 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
  4. 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...
  5. Modifications needed, but it works REALLY well! Thank you all. James IMG_1529.MOV
  6. 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
  7. 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
  8. 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...
  9. 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...
  10. 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
  11. 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.
  12. 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
  13. 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
  14. Looks really lovely. Do you have any metrics on how the mods have altered performance? Backlash, periodic error etc? James
  15. 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.
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