 
 <prompt> Wetin be di logic behind di leap year wey dem put for 1560? Based on di question wey dey up, write one context wey get di answer. E fit be 1 - 20 sentences. Context: <response>: Ancient tables bin dey provide di mean longitude of di sun. Christopher Clavius, di person wey design di Gregorian calendar, notice say di tables no gree on di time wen di sun pass through di vernal equinox nor on di length of di mean tropical year. Tycho Brahe also notice say some things dey off. Di Gregorian leap year rule (97 leap years in 400 years) na Petrus Pitatus of Verona bring am up for 1560. E notice say e dey consistent with di tropical year of di Alfonsine tables and with di mean tropical year of Copernicus (De revolutionibus) and Reinhold (Prutenic tables). Di three mean tropical years for Babylonian sexagesimals as di excess over 365 days (the way dem for don extract am from di tables of mean longitude) na 14,33,9,57 (Alphonsine), 14,33,11,12 (Copernicus) and 14,33,9,24 (Reinhold). All di values dey di same to two places (14:33) and dis na also di mean length of di Gregorian year. So Pitatus' solution for don make sense to di astronomers. 