Hello All ! I tried to calculate the sunrise time with the formula
cos(T)=-tan(lat)*tan(decl) I took the datas from the astronomical Almanac, here is an example for the 3. of september 1998 at latitude +46 Sun declination : 7 42 13.5 = 7.704 deg Rise time : 5h23m Set time : 18h35m Day length : 13h12m T=arccos(-tan(46)*tan(7.704))=98.05 deg =6.537 hours Calculated rise time : 12-6.537 = 5.463h = 5h27m47s Calculated set time : 12+6.537= 18.54h = 18h32m13s Calculated day length : 6.537*2 = 13.07 h = 13h04m25s As you see there is a difference between the calculated datas and the datas of the nautical almanac, the difference in the day length is about 8 minutes (2 degrees!) that's quite a lot. Why do I have such a difference? Did I do some wrong calculation or is this formula only approximative? Thanks Reto Ambrosini [EMAIL PROTECTED]
