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saac

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About saac

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  1. Not so sure about that, and certainly not the case for devices purchased on import from unregulated sources. Laser pointers sufficiently powerful to pop balloons or strike match heads are readily available on line. The lady in Clydebank was certainly not close to the device which left her permanently blind. I wont be using any laser pointer on any of my outreach events, they are simply not essential. Jim BBC News - Clydebank Woman Blinded By Laser Pointer
  2. Ok what about this line of thought , if the speed of light were infinite then what becomes of the value of the vacuum permeability (magnetic constant) and vacuum permittivity (electric constant). These are related to the speed of light - c =1/ (Eo Uo)^1/2, So do these constants become infinite to and what are the physical implications. Likewise what of the mass energy equivalence (E = mc^2), what would the physical implications be with respect to stellar nuclear processes. I think I read somewhere that if the fundamental constants like G or h etc were slightly different then our universe would not exist in the way it does now Jim
  3. Moral dilemma

    I think the test is to ask yourself is "have I added data or have I allowed data already present in the image to be better viewed above the noise". But I think it would be perfectly acceptable to apply different techniques to different areas of the image. I'm not a skilled imager though so others may have a different view. Jim
  4. I think I'm with Andrew on this one. In our everyday interaction the speed of light to all practical extent could be considered infinite. When I look at my wrist watch the light illuminating it travels the short distance to my eye instantly (as far as I am concerned), increasing its speed would make no discernible difference to my understanding of the image of the watch face it conveys. Ok our view of extremely distant (earliest) objects in the universe would be different, but that is it, they would just be different. More than happy to be wrong, now, later or before I posted this Jim
  5. Constant damp weather

    If you have water pooling on the concrete ground slab then deal with that first; you may find that standing water from the slab is evaporating into the space above. I'd find out why the water is pooling on the slab and deal with that first. Before installing a dehumidifier I would install a low level vent - effective ventilation requires both high and low level vents to ensure adequate air circulation. Your obsy sound very similar to mine in construction and as I said above I have no problems with dampness inside. Now this does not mean I don't get condensation/dew forming on the equipment (scope/mount) when the roof is off - nothing you can do to stop that really. However the amount of air circulating when my roof is closed and the obsy secure ensures that moisture gets carried away. Good luck with whatever you chose to do. Jim
  6. Constant damp weather

    Listen to what Astroboffin is saying here and you will save yourself a lot of time, effort and money. Ventilation to the point where you have free flowing air is key to a damp free environment. Heating and dehumidification are only required if you have constructed your observatory in such as way that you have eliminated completely or have restricted air flow. My observatory is single skin (cedar slats) no insulation or vapour barrier on the inside, with a 2 inch gap running the complete (circumference wall to roof). The base is a wooden sub-frame mounted on a concrete base which has a damp proof membrane. It was built around 4 years ago now and suffers from no internal dampness whatsoever despite being unheated and with only natural ventilation. I think quite often in our eagerness to "boiler plate" the construction of our observatories we actually build in condensation and dampens problems. Keep it simple keep air flowing. Jim
  7. Random Images

  8. They can be, but isn't that the nature of insurance, you need to ask that of somebody who has had their roof blown away by the wind. I bought mine two at a time over the space of 6 months. Jim
  9. felilimb these are excellent; thanks for sharing the references you used. I played around with the trial version of pixiinsight about a year ago for my first proper attempt at M31 then set it aside, but now I need to get around to purchasing the full version. I like the way your final image doesn't look overly processed. Jim
  10. Check these ones out, heavy duty and very much up for the job. I have them holding down my observatory roof for the past 4 years without incident. I think it was Gina that first posted details about them but highly recommended. Jim Blu-line trailer latches
  11. Today's APOD of the Bubble

    In the days to come Gorann it will be your photograph and it's selection for APOD you remember , nothing of your dull seminar will remain. Tell's us all something about what is important in life - do what you love and enjoy it. Well done, it really is a fantastic photograph and great use of the Liverpool Telescope, well done again. Jim
  12. Electrical supply to observatory

    Nothing wrong with it being a spur if done properly it can be entirely legal; that's how I have mine. As for voltage drop, do you have any indication at the obsy end to suspect you have anything wrong? Jim
  13. AP, a money pit?

    Spot on, it is a journey on which I'm constantly adjusting my expectations, goals and how much time/effort and expense I'm willing to invest. An that is all part of the enjoyment/attraction. I've certainly adjusted my thoughts on what I'm willing to spend mainly because of the limitations of our weather and what level of AP I'll achieve given the time I'm willing to invest. Jim
  14. facts

    I'm not one of them. ok I'll get my hat and coat
  15. I'd go with the first one - here you have control over what artificial lights may be in the field of view. In the second location your neighbour may decide to ruin your view by mounting a security light, if not now, perhaps sometime in the future. Good luck with your pier, it's well worth it. Jim
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