Why does the GPS model need the time zone other than to display local time? I
would think the calculations would be based on UT and position, both
available
from the GPS data.


Hi:

No, apparently not. If your time zone is incorrect, your initial alignment
stars as well as the Moon and planets will be "off".

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
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