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    Re: astrocompass still in use
    From: Robert Eno
    Date: 2002 Sep 26, 21:55 -0400

    Interesting application.
    How on earth did you manage to keep your astrocompass perfectly level whilst
    it was mounted on your boat?
    ----- Original Message -----
    Sent: Thursday, September 26, 2002 8:15 PM
    Subject: Re: astrocompass still in use
    > Quoting Paul Hirose :
    > > The astrocompass lives on. A major utility company in California
    > > allows engineers and architects to borrow one to evaluate solar access
    > > to a building site. Here is their online manual:
    > >
    > >
    > o_comp.shtml
    > >
    > I have an Astrocompass and I have fixed up a mounting on my boat for it. I
    > it about a year ago to check the Deviation of the boat's compass and a
    > interesting afternoons exercise it was too. I wonder if anyone else has
    found a
    > use for this old faithful.
    >     First the instrument was mounted and levelled. The Latitude was set on
    > micrometer scale and the Declination of the Sun set very roughly on the
    > sighting bar. The LHA of the Sun changes slowly so I wrote a simple
    program on
    > a Ti82 calculator to give the value to set on the LHA drum for every
    minute of
    > time and this was re-adjusted accordingly.
    >     Next the boat was carefully steered on 12 different COMPASS headings
    at 30
    > deg increments and the Astrocompass rotated to bring the Sun's shadow of
    > sighting bar onto the plastic graticule. At this point the TRUE direction
    > the boat was read of the base scale. Adding Variation to this data
    produces a
    > list values for plotting the Deviation correction graph.
    >     I have no idea of the origin of this instrument and I would like to
    hear if
    > anyone in the group does. I was taught how to use it in a Coastal Command
    > Lancaster many years ago and my instructor then had used one when flying
    > the Libyan dessert during the war. His magnetic compass had been destroyed
    > an enemy bullet.
    > I have an instruction book. If any one would like a copy my email is
    > jcs@cwcom.net.
    > Clive Sutherland.
    > Wantage, (where King Alfred burnt the cakes).
    > 51deg 38.2 min N    001deg 24.5min W

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