NO. 2 FORUM 277 Using the notation and sign convention adopted in The Nautical Almanac, the basic equations that have to be solved are: cos Z cos Alt = sin Dec cos Lat -cos Dec sin Lat cos (GHA + Long) sinZcosAlt= -cos Dec sin (GHA + Long) sin Alt = sin Dec sin Lat + cos Dec cos Lat cos (GH/1 + lon^) 4 Parker,