Determine latitude and longitude from the Sun

 From Vaughen:

Latitude= 90 - e + d

e: elevation of the Sun at noon

d: declination of sun on that day

Gnome exercise from Tam edu

RA and DEC of the Sun from HKO

Or using this approximation:

d = 23.45 * sin[(360/365)*(284+n)]degrees

n = number of days counted from January 1