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    Re: Seeing Moon rising an setting ?
    From: Jeremy C
    Date: 2010 Feb 19, 12:32 EST
    Well moon rise is difficult to observe in general.  Often it is during the day which makes for difficult observations due to haze and relatively low contrast of the moon near the horizon.  At night is easier to see, but even looking for it, I often don't see the moon until it is a degree or more above the horizon, again depending on the actual atmospheric conditions.  The same holds true trying to observe a star or planet.  I was gunning for an amplitude of a planet and had a heck of a time as the body (even a very bright Venus) disappeared from view as it passed below a degree above the horizon. 
     
    For my amplitude observation this summer, I had pre-calculated both time and azimuth and had my Alidade set up.  Moonrise was about the time of nautical twilight so the haze of night had not yet set in, yet the sky was dark allowing for maximum contrast.  The air was also clear as I mentioned.  I was looking through the telescope the moment the upper limb broke the horizon (when the moon was on the celestial horizon).  I also made an observation when the center of the body was on the visible horizon which can also yield an amplitude.
     
    The previous time I was not looking for it, but the moon was just off the port bow and my lookout and I at first thought it was a ship's running light.  After it rose a bit more, I was more sure of what I was looking at, and wished that I had recognized it sooner to get an amplitude.  This was again a very clear night, but this time it was on the midnight watch, so about 1 AM.
     
    I can't say that I make a huge effort to observe the moon at rising, but I often try to watch it set while I'm on watch with little success.  I certainly would take this as hard and fast evidence as I have not tried to be scientific about it.
     
    Jeremy
     
    In a message dated 2/19/2010 4:30:21 A.M. Eastern Standard Time, marcel.e.tschudin@gmail.com writes:
    Thank you, Jeremy, for mentioning your experience. From what you say
    it seems indeed not to be possible to see the moon at the horizon
    under "normal" atmospheric conditions except under an exceptionally
    clear sky. You wrote "seeing the actual limb on the horizon at sea is
    quite a bit more rare than observing the sun rise or set" and "I have
    seen the moon rise twice in the last three years". In order to get a
    better feeling on how rare: Resulted the two observations just by
    "accidental" noticing that an amplitude observation would be possible
    or did you over the three years regularly look out whether it would be
    possible to take such an observation?

    Marcel



       
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