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    SGL 2017 SP

NickK

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About NickK

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    Near Guildford, UK
  1. I think I will have to do an update.. and recompile everything as I have a bleeding edge install (at the time) - full 64bit on the C2 ODroid ARM. Determined to make more of an effort to get some sky time this winter.
  2. I'm thinking .. imagine a Alt-Az mount with one or more scopes with cameras. On a 20 minute image, the sky will rotate and leave arcs on the camera. However if the image is de-rotated in software using a 100:1 sub grid - what problems could you get? The arcs would vary in size however given you know the time and the shift, it should be possible to revert the image by transform stacking. The only issue is over saturated stars arching and obliterating the signal over the entire arc - however if you've got to that point then there's a bigger issue of exposure control The reverse stacking could also be used to reduce noise further. The main issue I can see is that as the atmosphere wobbles the arc will change - a bit like the thickness of a pen changing and the hardness of the nib being pushed down. You could even take a sub shot between the long exposures although this would warm up the camera it would allow registration if the algorithm isn't very advanced.
  3. Not much progress since the last update the job has been OTT busy :/ I have just watched an interesting lecture on deep learning for image processing. The interesting bit is that the model they use for identification looks similar to what I'm doing here i.e. using convolution filters and then a 3D output of correlation for the neural net. The difference here is that I'm using FFT full image they're using linear sub-images that are down-sized. In essence they're doing a correlation and then working out if the pattern of correlations from multiple feature filters = man, dog or raspberry based on the net recognising the location and the object input patterns it's trained on. The job has a (legal) mandatory 2 week vacation so as part of that I get to tune out and one of those is to have a think about this in further detail.
  4. ... repeating myself.. new post Interesting - the main issue is that steppers make it very hard to measure the current without being inline at the rate required. So the limiting driver is a good solution. What options for step movement? Well typically the 10:1 requirement for accuracy means you're only attempting to get a smooth movement but it's still not smooth and may vary in smoothness over the rotation.
  5. One of the INDI stepper drivers use it.
  6. One issue we've had with green heavy duty bags over the mount is that magpies and jackdaws seem to peck holes in it. They also become brittle over time, we're on our second. I have an inner tubular garden bag that has wire hoops , a heavy duty bin bag that guarantees water proofing and then the garden back over the top.
  7. I found yet another negative aspect - which is any PSF noise, at stacking, becomes a valid signal. I have an idea to remove the noise from the PSF (as I do with the main image) which should improve things massively. Now I'm comfortable that the processes are good - after the noise I may look to start being a bit more rigorous and optimise (possibly GPU it).
  8. So... I've been playing more.. Centre is a 3D plot of the input area.. showing the input with stars - including a saturated star (large sloped star). The output looks like it loses detail.. but it's down to scale - so the right plot shows the rebuilt saturated stars and deconvolution, the right shows an autostretched lower clipped (you can see the base of the PSF as weird circle) - simply because the full scale plots of the saturated stars really dwarf the normal signal level! So the output needs double precision! I'm currently using TIFF but I think I may need to switch to FITS! So improvements.. there is still a little noise being added by the PSF still (the little peaks near the larger stars) which is next on the hit list!
  9. The fun is that everything is still moving and it's all about having a cone of error that you're reducing iteratively - curve fitting. You can plate solve multiple locations, the time to move, sample and then plat solve needs to be built into the calculation. The reason that people pick locations on the horizon and zenith is to give the largest movement - thus, in theory, the best accuracy.
  10. Well got a good hour of clear gaps - great for push-to or binos. Andromeda through the binos
  11. Bright patch.. almost sunny!... actually - SUN \
  12. Accuweather says 1% chance of rain.. it's raining. I'd prefer 99% chance and it being clear!
  13. Awesome episode!
  14. Minor boo boo on my part - put 1x hog roast, not 2x.. normally there's plenty left over so if I could pay for the additional ticket .. otherwise Sandrine gets the hog roast!
  15. looking at the weather we should see some wind move the cloud at 11pm onwards.. but gaps rather than clears skies... but lucksall has it's own microclimate.