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JamesF last won the day on April 18

JamesF had the most liked content!

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About JamesF

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    Wiveliscombe-ish, Somerset
  1. https://www.bbc.co.uk/news/science-environment-54721921 Nice work on the Slovenian church. Seeing buildings lit up at night like beacons for no real benefit is one of the things that does wind me up. James
  2. I'm not far from Cardiff as the meteor falls and I have to agree the weather has been pretty appalling over the last few months. There have been clear nights, but often after wet days when the seeing becomes quite mushy thanks to all the moisture in the air. Getting on with other things is my usual way of coping, though options are a bit thinner on the ground now the clocks have gone back. As long as I'm actually being productive somehow I can handle the barren spells. Tonight I wouldn't have been able to go out anyhow as I have to work, but given a free afternoon I spent it with my daughter, reorganising the polytunnel so we can fit more plants in next year, which means I still feel as though I've achieved something of value to me today. James
  3. So you can talk out of a place the sun don't shine? James
  4. I don't appear to have any contact details for Tom I'm afraid. The only thing I can think of is to try to contact him directly through the website. I suspect however that it will go to the same place as the signup requests. James
  5. Personally I'd prefer to avoid using wifi for transferring large files around, including downloaded frames from modern astronomy cameras. I'd always use a wired connection if I could. In my observatory the piers are sufficiently close to the warm room that I can run HDMI and USB cables to a KVM switch from the small form-factor PCs on the piers so I can run everything that way. If I'd not been able to do that I'd have used the wired ethernet connections to control the pier computers from a Kstars front-end running in the warm room. James
  6. Insulated clothing already?! I'm still wearing shorts and t-shirts most of the day (I have preferred something longer to keep my knees warm in the evening for the last couple of weeks, I admit). And no, I am not a postie :D James
  7. I never realised there was so much going on there. Nice one :) James
  8. Thanks. There's still something here that isn't clear to me yet though, and I'm not sure what it is. I may just be being dense, over-complicating things or modelling the entire thing in my head in the wrong way. If I think about a molecule of water at, say, "average" sea level in the middle of the sea with the Moon directly above it, so it's actually sitting on a line drawn between the centre of the Moon and the centre of the Earth, there's a force on the molecule towards the centre of the Earth due to the Earth's gravity. There's also a much, much smaller force on the molecule towards the Moon due to the Moon's gravity. The net force is therefore always towards the Earth. So how can that molecule of water move towards the Moon? It's also just occurred to me to wonder if there are "atmospheric tides" as well as sea tides James
  9. That looks very close. Mine didn't ever fail in that way so I'm afraid I can't offer any help at this stage. James
  10. My understanding is that some jobs work well on a GPU whilst others don't, depending on the nature of the code. I suspect most raw colour to RGB conversions can be done with a kernel for combining pixels, so I think that might work well. It's a bit of a moot question at the moment however, as I don't currently have a suitable GPU to work with. James
  11. That will keep me quite for a while Thank you, Andrew. James
  12. Each frame from the 462MC as it comes off the camera is going to be just over 2MB I think. If it's converted to RGB rather than stored as raw colour then that will triple, so 67 frames would be over 400MB plus the overheads of the file format (probably not much for 67 frames). So you're probably in the right ballpark there. Reducing the frame size or not converting the frame to RGB would probably improve performance, and you'd not need to save so much data. I have been wondering if the demosaic process might be something suitable for pushing off onto a GPU. Definitely something to look at for the future. James
  13. So you'd say that only gravity is required to explain the effect, in which case given my stationary Earth and Moon example presumably we'd get similar tidal bulges, at least for a while? James
  14. Double stars are a favourite, I believe. Perhaps specific types of star too, such as carbon stars. James
  15. I feel the need to return to this because my brain just wouldn't let it go and I spent part of another night lying in bed trying to properly understand what's going on. (I hope I'm not the only person who does this sort of thing. Not that there's much I can do about it if I am.) First I tried to decide, if the Moon and Earth were stationary relative to each other, would there be a tidal bulge and if so, how would its height compare with the tides we have in the "real world"? I couldn't make up my mind about that as presumably they'd just crash into each other after a while. Ignoring the effect of the Moon for a moment, I came to believe that there may be no force on the water causing it to move away from the planet. It's just attempting to continue in a straight line at a constant speed given the inertia it has gained from the Earth's rotation (though I'm not certain about this for liquids, and perhaps particularly for polar liquids). So presumably the height of a body of water is given by some sort of equilibrium being reached between the water continuing to move in a straight line and the force on it due to the Earth's gravity? If that is the case then presumably the effect of the Moon is to allow that equilibrium point to move away from the surface of the Earth because it reduces the total force on the water in the direction of the centre of the planet? It also occurred to me to wonder: do the seas and oceans "slosh towards" the land on their western edges as the Earth rotates to the east? For example given two land masses of equal height above the centre of the Earth with a large body of water between them, would the water level be higher when measured against the land to the west than the east? James
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