I needed to know at what time the sun would be positioned due north, to enable me to validate some previous measurements.

I found the following US Navy website which has a universal calculator allowing you to find this data for your lat/long which can be extracted from your iphone or any GPS.

http://aa.usno.navy.mil/data/docs/mrst.php

For readers in the northern hemisphere, the calculator does allow for north and south latitudes, as well as west and east longitudes…