day, month and year
19 September 1979
31 May 1949.
The Gregorian reform contained two parts: a reform of the Juliancalendaras used prior to Pope Gregory XIII's time and a reform of the lunar cycle used by the Church, with the Julian calendar, to calculate the date of Easter
September 7, 1533 was a Thursday, if Gregorian date calculators work back that far.
My calendar is a Gregorian calendar
America, both north and south, use the Gregorian calendar as a general rule. There are groups which may use other calendars for certain religious ceremonies but the date most would adhere to is the Gregorian date.
Pope Gregory I the Great is the pope you are referring to. He did not write Gregorian Chants. He compiled and cataloged the plain songs that were used in liturgies at the time. Later they became known as Gregorian Chants.
18 Rajab 1342
19 September 1979
In the Gregorian calendar, December 31st
The Bengali date 21 Boishakh 1387 corresponds to May 4, 1980, in the Gregorian calendar. The Bengali calendar is approximately 594 years ahead of the Gregorian calendar, which is why the conversion yields this date.
The Bengali date 2 Ashar 1370 corresponds to July 16, 1963, in the Gregorian calendar. Bengali dates are based on the Bengali calendar, which is roughly 594 years ahead of the Gregorian calendar.
Monday 27 October 1952
The Tanabata Festival is held on July 7th on the Gregorian calendar.
If that is a Gregorian date, it's a Sunday. However, the Gregorian calendar did not yet exist in 1491, so it might be a Julian date, which would make it a Tuesday.
The date 23 Katak 1985 corresponds to December 8, 1985, in the Gregorian calendar. Katak is a month in the Nepali calendar, which typically falls around November to December in the Gregorian calendar.
The Bengali date 18 Falgun in the year 1395 corresponds to March 2, 1989, in the Gregorian calendar. The Bengali calendar is approximately 593 years ahead of the Gregorian calendar, which is why the conversion results in this specific date.