sentences:  It was Swami Vijnanananda (who became Math president in 1937–38), an astrologer, who decided that Ramakrishna Mission would follow this almanac as it was more scientific.The difference occurs because the two schools follow different calendars of luni-solar movement on which tithis are based.While "Gupta Press Panjika" follows 16th century Raghunandan's work "Ashtabingshatitatwa" based on the 1,500-year-old astronomical treatise, "Suryasiddhanta".