It was a Monday.
March 13th, 1980 was a Thursday.
13 March 1980 was a Thursday.
1 March 1980 was a Saturday.
March 29, 1980, was a Saturday.
14 March 1980 was a Friday.
March 6th, 1980 fell on a Thursday.
March 31st 1980 was a Monday.
March 18, 1980 fell on a Tuesday.
Since the time of the 1980 beginning of spring in the northern hemisphere was 11:10 AM GMT, it may have been the same day around the whole world: March 20.
1980 was a leap year that started on a Tuesday, so March 4th was a Tuesday.
a Friday
Saturday