Re: Question about stopwatches

From: Mike Waterman (
Date: Wed Jun 14 2000 - 09:16:34 PDT

  • Next message: Judy May: "Telescope for observing satellites"

    Jonathan Wojack (June 5th) asked:
    > How do you people time flashes of satellites seen in binoculars?  You
    > have a stopwatch in one hand, binoculars in the other hand.....? 
    One aid to observing is to have binoculars on a tripod. Large
    binoculars are difficult to hold steady for long, and benefit most
    from a tripod. My 11*80 normally stay on their tripod, my 7*50 are
    normally hand-held.
    My tripod has a (normally) vertical tube with clamps
    at "C" on the diagram so that the binoculars can be raised or lowered.
    Some binoculars have a threaded hole so that they can be easily attached
    to a standard photographers tripod. Mine did not, so I made a wooden cradle,
    onto which the binoculars are normally bolted.
    Elevation is lightly clamped, just enough so the binoculars do not tilt
    when not held. There is no azimuth clamp. 
    The tripod can be used as normal with 3 legs on the ground up to
    elevation about 40 degrees. I am usually sitting, but sometimes
    standing. This needs no hands to hold the binoculars.
    eye <) =====
           / | \
          /  |  \
        /    |    \
       /           \
    For higher elevations I tilt the tripod so that the furthest leg leaves
    the ground. leaning back in the chair.
     \ ||
       || \
       \/   \__________
            |\   /
            | \ /
            |  \
            | / \
    Another feature of a tripod is that you can take your eyes away from
    the binoculars, and the binoculars stay pointing in the same direction.
    This is useful if you use faint reference stars which are not easy to
    identify, so you need to make notes, perhaps a diagram of the field of 
    Another aid is to have a simple push-button instead of a stopwatch. I use
    a pushbutton mounted on a small plastic tube. It is easier to hold than
    a stopwatch [or you could use a foot-operated button]. A pushbutton could
    feed into a normal (electronic) stopwatch, but in my case goes directly
    to a computer. This avoids errors in writing down times. Also, since the
    computer's clock stays on UT you dont have to bother about summer/winter
    If there is a train of many satellites in a short time (such as the Mir
    fragments in 1996) then I can use my left hand to press the button and 
    steady the binoculars, and the right hand to note the position of each bit
    and its magnitude; without taking my eyes off the sky.
    Mike Waterman
    Site Yateley = COSPAR 2115 =  51.3286N  0.7950W  75m.
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