Leap year starting on Sunday

Template:Short description A leap year starting on Sunday is any year with 366 days (i.e. it includes 29 February) that begins on Sunday, 1 January, and ends on Monday, 31 December. Its dominical letters hence are AG. The most recent year of such kind was 2012, and the next one will be 2040 in the Gregorian calendar<ref name="math">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> or, likewise 2024 and 2052 in the obsolete Julian calendar.

This is the only leap year with three occurrences of Friday the 13th: those three in this leap year occur three months (13 weeks) apart: in January, April, and July. Common years starting on Thursday share this characteristic, in the months of February, March, and November.

Additionally, these types of years are the only ones which contain 54 different calendar weeks (2 partial, 52 in full) in areas of the world where Monday is considered the first day of the week.

This year has five months (January, April, July, September and December) which begin on a weekend-day. This is the greatest possible number of months to begin on a weekend-day in a given year; this is the only kind of year in which this occurs.

CalendarsEdit

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any leap year starting on Sunday (dominical letter AG)
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Applicable yearsEdit

Gregorian CalendarEdit

Leap years that begin on Sunday, along with those starting on Friday, occur most frequently: 15 of the 97 (≈ 15.46%) total leap years in a 400-year cycle of the Gregorian calendar. Thus, their overall occurrence is 3.75% (15 out of 400).

Gregorian leap years starting on Sunday<ref name=math/>
Decade	1st	2nd	3rd	4th	6th	7th	9th	10th
16th century	prior to first adoption (proleptic)						1584
17th century		1612		1640		1668		1696
18th century	1708			1736		1764		1792
19th century	1804			1832	1860		1888
20th century			1928		1956		1984
21st century		2012		2040		2068		2096
22nd century	2108			2136		2164		2192
23rd century	2204			2232	2260		2288
24th century			2328		2356		2384
25th century		2412		2440		2468		2496
26th century	2508			2536		2564		2592
27th century	2604			2632	2660		2688

400-year cycle
0–99	12	40	68	96
100–199	108	136	164	192
200–299	204	232	260	288
300–399	328	356	384

Julian CalendarEdit

Like all leap year types, the one starting with 1 January on a Sunday occurs exactly once in a 28-year cycle in the Julian calendar, i.e., in 3.57% of years. As the Julian calendar repeats after 28 years, it will also repeat after 700 years, i.e., 25 cycles. The formula gives the year's position in the cycle ((year + 8) mod 28) + 1).

Julian leap years starting on Sunday
Decade	1st	2nd	3rd	4th	5th	6th	7th	8th	9th	10th
15th century	1408			1436			1464			1492
16th century		1520			1548			1576
17th century	1604			1632		1660			1688
18th century		1716			1744			1772		1800
19th century			1828			1856			1884
20th century		1912		1940			1968			1996
21st century			2024			2052		2080
22nd century	2108			2136			2164			2192

HolidaysEdit

InternationalEdit

Valentine's Day falls on a Tuesday
The leap day (February 29) falls on a Wednesday
World Day for Grandparents and the Elderly falls on its earliest possible date, July 22
Halloween falls on a Wednesday
Christmas Day falls on a Tuesday

Roman Catholic SolemnitiesEdit

Epiphany falls on a Friday
Candlemas falls on a Thursday
Saint Joseph's Day falls on a Monday
The Annunciation of Jesus falls on a Sunday
The Nativity of John the Baptist falls on a Sunday
The Solemnity of Saints Peter and Paul falls on a Friday
The Transfiguration of Jesus falls on a Monday
The Assumption of Mary falls on a Wednesday
The Exaltation of the Holy Cross falls on a Friday
All Saints' Day falls on a Thursday
All Souls' Day falls on a Friday
The Feast of Christ the King falls on November 25 (or on October 28 in versions of the calendar between 1925 and 1962)
The First Sunday of Advent falls on December 2
The Immaculate Conception falls on a Saturday
Gaudete Sunday falls on December 16
Rorate Sunday falls on December 23

Australia and New ZealandEdit

Australia Day falls on a Thursday
Waitangi Day falls on a Monday
Daylight saving ends on its earliest possible date, April 1
ANZAC Day falls on a Wednesday
Mother's Day falls on May 13
Father's Day falls on September 2
Daylight saving begins on its latest possible date, September 30 in New Zealand and October 7 in Australia – this is the only leap year where the period of standard time over the winter months lasts 26 weeks in New Zealand and 27 weeks in Australia (in all other leap years, it lasts only 25 weeks in New Zealand and 26 weeks in Australia)

ReferencesEdit

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1 Jan	Count	Ratio	31 Dec	DL	DD	Count	Ratio	31 Dec	DL	DD	Count	Ratio
Year starts			Common years					Leap years
Sun	58	14.50 %	Sun	A	Tue	43	10.75 %	Mon	AG	Wed	15	Template:03.75 %
Mon	56	14.00 %	Mon	G	Wed	43	10.75 %	Tue	GF	Thu	13	Template:03.25 %
Tue	58	14.50 %	Tue	F	Thu	44	11.00 %	Wed	FE	Fri	14	Template:03.50 %
Wed	57	14.25 %	Wed	E	Fri	43	10.75 %	Thu	ED	Sat	14	Template:03.50 %
Thu	57	14.25 %	Thu	D	Sat	44	11.00 %	Fri	DC	Sun	13	Template:03.25 %
Fri	58	14.50 %	Fri	C	Sun	43	10.75 %	Sat	CB	Mon	15	Template:03.75 %
Sat	56	14.00 %	Sat	B	Mon	43	10.75 %	Sun	BA	Tue	13	Template:03.25 %
∑	400	100.0 %				303	75.75 %				97	24.25 %

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