Determination of the day of the week row C) to find the dominical letter that is E. The letter for September 18 is B, so the day of the week is Thursday. Use 16 (in the Julian century row, column E) and 76 (in row D) to find the dominical letter that is A. February 23 is a "D" day, so the day of the week is Wednesday. In a handwritten note in a collection of astronomical tables, Carl Friedrich Gauss described a method for calculating the day of the week for 1 January in any given year. He never published it. It was finally included in
IAU 24 Hour World Championship IAU 24 Hour World Championship The IAU 24 Hour World Championship is an annual international 24-hour run competition organised by the International Association of Ultrarunners (IAU). Preceded in 2001 by the IAU World 24 Hours Track Championships, as a track running event, this competition became the IAU World 24 Hours Challenge proper in 2003. The road running event was later upgraded to World Championships status after 2006. It is one of the IAU's four main world championship events (alongside the 100 km World Championships, 50 km World Championships, and Trail World Championships) and is the only one with a limited