Azimuth - elevation input format:
Describe the horizon by entering lists of space-separated values corresponding to the
azimuth (0-360 degrees) and angular elevation (0-90 degrees) of points on the horizon. If
you have a full 2-pi field of view, i.e. no shielding, leave blank or enter zeros.
This procedure
means that in the field you should have approximated the horizon by a series of points with
straight lines between them. Note that this is not the same as approximating the horizon by
the average elevation angle in a series of equally spaced quadrants, octants, etc.: the latter procedure is
inappropriate because the relationship between rise angle and cosmic-ray shielding is
nonlinear, and it will underestimate the actual shielding in the case of large and variable horizon angles.
For example, if the horizon around you looked as follows:
You might approximate the horizon like this:
And enter the following series of points:
Azimuths:
0 55 115 235 310
Elevations:
3 0 5 0 0
This particular horizon has a shielding factor of 0.99995, that is, so small that we really didn't need to bother.
(Thanks to David Metsky at Dartmouth College for the 360-degree panorama of the view from
Mt. Avalon that we've borrowed here)
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