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'A detailed description of this technique  (called Slope Fitting) can be
found at the StarPath site'

It certainly can. Its wonderful, the way this group generates so much
information.

The advantage of the method I use (see earlier message 'good data from
bad') is that it uses printed forms, one to calculate the 'change of
altitude' slope, the other is for plotting, with the divisions for time
and altitude marked, and spaces for noting the relevant data.

One of the biggest practical problems I come across when investigating
new navigational techniques is finding a methodical routine to note down
the workings. Otherwise I can't make sense of my own workings when later
on I need to follow the process again. Finding this 'change of altitude'
technique was one kind of Eureka! moment. Others, less dramatic but so
valuable, have come when I find a form to follow that allows me to
simplify and codify some process, that turns an interesting theory into
a practical routine to be followed. Another advantage is that it
simplifies checking the work for errors. Another is that you learn to
instantly identify the different printed forms, instead of pondering a
page covered in hieroglyphics and wondering just what that was all
about.

That book ('The Complete On-Board Celestial Navigator') has another form
for sight reductions: its the one I use because its clear and simple to
follow, even when the data comes from somewhere else; for example the
Silicon Sea series.

Peter Fogg

   

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