Leap year starting on Monday
A leap year starting on Monday is any year with 366 days (i.e. it includes 29 February) that begins on Monday, 1 January, and ends on Tuesday, 31 December. Its dominical letters hence are GF, such as the years 1912, 1940, 1968, 1996, 2024, 2052, 2080, and 2120 in the Gregorian calendar or, likewise, 2008, 2036, and 2064 in the obsolete Julian calendar. 
Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths. This leap year contains two Friday the 13ths in September and December. Common years starting on Tuesday share this characteristic.
Coptic calendar
The following table refers to dates for Coptic years not containing February 29. Such years are preceded by a Coptic leap day at the end of the preceding year. This causes dates to move one day later in the Julian and Gregorian Calendars from the Coptic New Year's Day until the leap day of the Julian or Gregorian Calendar respectively.