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andrew s

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About andrew s

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    Cheshire
  1. Clear Outside is predicting 5 clear nights in Castillejar and with little or no moon are we going to be treated to some images from the rig this week? Regards Andrew
  2. Can't you just use a sub frame during focusing? Pick a line and do a ROI round it. Regards Andrew
  3. Dec calibration between -20 to +20 means point your scope at a declination between those limits. It seems to me you need to study some basics. It is fine if your not interested but you would find things easier if you understood the basic concepts. Good luck. Regards Andrew
  4. Some filters have quite high light leakage out of band either in the IR or UV so stacking in that case may not be such a bad idea. If stacking I would go from narrowest to widest as the light goes target to camera to minimise reflections. Regards Andrew
  5. Third Flare at a higher cadence ~ 15s (11s exp) binned 3x3. I was beginning to wonder if changing the exp and binning had jinked me. This time it was QY Aur Regards Andrew
  6. The outer layers are very loosely held by the low surface gravity. The slightest push and pull can set it wobbling like a giant soap bubble in the wind. The internals have instabilities due to changing opacity with temperature and pressure leading to the multiple oscillations and periods seen. t's a very dynamic atmosphere. The core is not impacted much by all this which is why the latest changes probably don't have anything to do with it going SN any time soon. Regards Andrew
  7. Collimation is a complex process. What you need and how to do it depends on what stage you are at. The aim is to get all the components lined up on a common optical axis. This includes the focuser, secondary mirror and primary mirror. The secondary does not have a unique optic axis and nor will a focuser if the tools or eye pieces can be offset with a locking screw or band. Even a star test cannot tell if the secondary is aligned properly. The more you understand the process the better it gets. I used a sight tube to align the focuser and center the secondary under it. Then a Cheshire to align the primary followed by an auto collimator for fine tuning the secondary. Once collimated try it in different orientations to see if it stay collimated (the auto collimator is very sensitive). If it shifts too much find out what is moving and strengthen it. If all this is too much trouble the advice in the posts above is fine. Regards Andrew
  8. Beautiful image the HST will be missed the new scope will not have all the capability of the HST especially in the UV. Regards Andrew
  9. It's a right of passage for Newt owners none of this just point a shoot as with the Frac boys and girls. Unfortunately, it is the poor design of the mirror supports that allow collimation, plus poor focuses that mean you have to do it at all. I had a home made Newt with a steel box frame and I drilled 3/4" holes in it and it did not need readjusting. Regards Andrew
  10. Google is your friend. Regards Andrew
  11. No good reason at all. The outer layers of super giants are decoupled from the core by a thermal lag and largely do their own thing. Obviously as the net energy output from the core changes it has a major influence on the outer layers over time. However, once fusion in the core stops and it collapses it does so far too quickly for the outer layers to react until they are hit by the neutrino burst and shock waves. Regards Andrew
  12. I think different things are being confused here. Putting it in simple terms. For the mount to balance the moments tending to turn it one way must balance those turning it the other way. The moment is the mass x distance of mass from the fulcrum. So twice the weight half the distance for the same moment. Static force on the mount is proportional to the total mass twice the mass twice the force. Dynamic load depends on the moment of inertia which is the mass x distance^2 so as in the second paragraph in the quote the load on the motors accelerating the mount are reduced by increasing the mass of the counterweights. Regards Andrew
  13. If you Google rotation of betelgeuse you will get lost of links to explain it's rotation. Its normally measured via spectroscopy but betelguse is so large it can be imaged via interferometry. Regards Andrew
  14. Only intended as a little fun for a Friday afternoon! Regards Andrew
  15. Not really you can coat almost any glass without its type have any effect. Regards Andrew
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