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Pompey Monkey

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About Pompey Monkey

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    Sub Dwarf

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  • Interests
    Astronomy, cycling, science.
  • Location
    Hampshire, UK
  1. Yes you did I agree that subtracting the uncalibrated darks also removes the bias from the lights. I just prefer to remove the bias from all my files so I know that I have "a level playing field" from the start.
  2. Wow! that's a lot of explanation. Thanks. The way my, rather limited, interpretation is if you subtract the bias (and dark if necessary on long exposures), then: Flats (Vignetting/dust bunnies) are a multiplicative correction factor, Gradients are subtractive. Yes/no?
  3. They do indeed add a constant value to the image to avoid negative numbers. However, this is a constant and is called the pedestal. It is not the bias signal. The bias is electronic noise generated by the sensor and camera electronics as the image is read off the chip. Fortunately, this noise is fairly consistent for every image read and, by averaging many bias files, a model can be built ("master bias") that can be subtracted from every image to dramatically reduce the read noise from the camera/sensor. Bias should be subtracted from every image read from the camera i.e. lights, flats and darks. Except bias frames, of course
  4. The ftdi chipsets assign themselves a com number on first plugin. After that, it matters not which usb socket you connect to, it will retain the port number (unless you want to change it). The improved reliability over the prolific chips is like night and day!
  5. Ad-blocker is your friend Although I may have a go at making a Pi-hole soon: https://pi-hole.net/
  6. You could always lend it to another local astronomer who would benefit from it.
  7. Your scope is a reflector = no chromatic aberration (CA). The (cheap) barlow has at least one refracting lens = possibility of CA. 99.5% it's the barlow.
  8. East-West is almost Up-Down in you image. As the (very wiggly) star trails in your image are neither vertical or horizontal, I'd say it was a balance/weight/gear slipping/bearing issue. So it is not the RA tracking. The movement is largely in the East-West direction, so my guess is that the DEC axis was continually slipping in little increments, and then these movements were enough to also upset the RA tracking somewhat. This also fits in with the Pleiades tracking OK, as the more vertical the scope gets, the lower the turning moment it produces on the DEC axis. Balance again and make sure that the clutch is done up a wee bit tighter next time, and see what happens.
  9. Great idea, I will borrow it. Of course the total eclipses will take priority!
  10. I do believe that you have imaged the Solarians mass transit system! Seriously, that is absolutely brilliant!
  11. If it doesn't cost you anything/much to try - why not have a go? I think your limitation might be with your mount - what one is it? Also, I think that @Stub Mandrel has probably done what you are suggesting - and he will know everywhere it could go wrong!
  12. Super! What's all that black tape doing? I hope it's just a low voltage cable!!
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