Daylight Savings Time File

The Daylight Savings Time file (dst.dat) is an editable ASCII text file that contains historical and predicted start and end dates for daylight savings time (DST). This data file is used by the TimeUtilities.IsInDaylightSavings() method.

Since the format of FreeFlyer's Daylight Savings Time file is an ASCII text file, the user can easily edit or add new lines as desired. Each line lists the start and end date and time for DST (in UTC Julian (GSFC)) and a comment (for user benefit).

The default file provides values that correlate to the USA’s standard declaration of DST dates: “The United States and Canada observe DST from the second Sunday in March to the first Sunday in November”. More information about the history of Daylight Savings Time can be found here: https://aa.usno.navy.mil/faq/daylight_time.

454.5834375 657.58343749999995 //Apr 05 1942 02:00:00.000, Oct 25 1942 02:00:00.000

818.58343749999995 1028.5834374999999 //Apr 04 1943 02:00:00.000, Oct 31 1943 02:00:00.000

1182.5834374999999 1392.5834374999999 //Apr 02 1944 02:00:00.000, Oct 29 1944 02:00:00.000

1546.5834374999999 1756.5834374999999 //Apr 01 1945 02:00:00.000, Oct 28 1945 02:00:00.000

1917.5834374999999 2120.5834374999999 //Apr 07 1946 02:00:00.000, Oct 27 1946 02:00:00.000

2281.5834374999999 2484.5834374999999 //Apr 06 1947 02:00:00.000, Oct 26 1947 02:00:00.000

2645.5834374999999 2855.5834374999999 //Apr 04 1948 02:00:00.000, Oct 31 1948 02:00:00.000

3009.5834374999999 3219.5834374999999 //Apr 03 1949 02:00:00.000, Oct 30 1949 02:00:00.000

3373.5834374999999 3583.5834374999999 //Apr 02 1950 02:00:00.000, Oct 29 1950 02:00:00.000

3737.5834374999999 3947.5834374999999 //Apr 01 1951 02:00:00.000, Oct 28 1951 02:00:00.000

4108.5834375000004 4311.5834375000004 //Apr 06 1952 02:00:00.000, Oct 26 1952 02:00:00.000

4472.5834375000004 4675.5834375000004 //Apr 05 1953 02:00:00.000, Oct 25 1953 02:00:00.000

4836.5834375000004 5046.5834375000004 //Apr 04 1954 02:00:00.000, Oct 31 1954 02:00:00.000

5200.5834375000004 5410.5834375000004 //Apr 03 1955 02:00:00.000, Oct 30 1955 02:00:00.000

5564.5834375000004 5774.5834375000004 //Apr 01 1956 02:00:00.000, Oct 28 1956 02:00:00.000

5935.5834375000004 6138.5834375000004 //Apr 07 1957 02:00:00.000, Oct 27 1957 02:00:00.000

6299.5834375000004 6502.5834375000004 //Apr 06 1958 02:00:00.000, Oct 26 1958 02:00:00.000

6663.5834375000004 6866.5834375000004 //Apr 05 1959 02:00:00.000, Oct 25 1959 02:00:00.000

7027.5834375000004 7237.5834375000004 //Apr 03 1960 02:00:00.000, Oct 30 1960 02:00:00.000

7391.5834375000004 7601.5834375000004 //Apr 02 1961 02:00:00.000, Oct 29 1961 02:00:00.000

7755.5834375000004 7965.5834375000004 //Apr 01 1962 02:00:00.000, Oct 28 1962 02:00:00.000

8126.5834375000004 8329.5834374999995 //Apr 07 1963 02:00:00.000, Oct 27 1963 02:00:00.000

8490.5834374999995 8693.5834374999995 //Apr 05 1964 02:00:00.000, Oct 25 1964 02:00:00.000

8854.5834374999995 9064.5834374999995 //Apr 04 1965 02:00:00.000, Oct 31 1965 02:00:00.000

9218.5834374999995 9428.5834374999995 //Apr 03 1966 02:00:00.000, Oct 30 1966 02:00:00.000

9582.5834374999995 9792.5834374999995 //Apr 02 1967 02:00:00.000, Oct 29 1967 02:00:00.000

9953.5834374999995 10156.583437499999 //Apr 07 1968 02:00:00.000, Oct 27 1968 02:00:00.000

10317.583437499999 10520.583437499999 //Apr 06 1969 02:00:00.000, Oct 26 1969 02:00:00.000

10681.583437499999 10884.583437499999 //Apr 05 1970 02:00:00.000, Oct 25 1970 02:00:00.000

11045.583437499999 11255.583437499999 //Apr 04 1971 02:00:00.000, Oct 31 1971 02:00:00.000

11409.583449074074 11619.583460648148 //Apr 02 1972 02:00:00.000, Oct 29 1972 02:00:00.000

11773.583472222223 11983.583472222223 //Apr 01 1973 02:00:00.000, Oct 28 1973 02:00:00.000

12144.583483796296 12347.583483796296 //Apr 07 1974 02:00:00.000, Oct 27 1974 02:00:00.000

12508.583495370371 12711.583495370371 //Apr 06 1975 02:00:00.000, Oct 26 1975 02:00:00.000

12872.583506944444 13082.583506944444 //Apr 04 1976 02:00:00.000, Oct 31 1976 02:00:00.000

13236.583518518519 13446.583518518519 //Apr 03 1977 02:00:00.000, Oct 30 1977 02:00:00.000

13600.583530092592 13810.583530092592 //Apr 02 1978 02:00:00.000, Oct 29 1978 02:00:00.000

13964.583541666667 14174.583541666667 //Apr 01 1979 02:00:00.000, Oct 28 1979 02:00:00.000

14335.58355324074 4538.58355324074 //Apr 06 1980 02:00:00.000, Oct 26 1980 02:00:00.000

14699.58355324074 4902.583564814815 //Apr 05 1981 02:00:00.000, Oct 25 1981 02:00:00.000

15063.583564814815 15273.583576388888 //Apr 04 1982 02:00:00.000, Oct 31 1982 02:00:00.000

15427.583576388888 15637.583587962963 //Apr 03 1983 02:00:00.000, Oct 30 1983 02:00:00.000

15791.583587962963 16001.583587962963 //Apr 01 1984 02:00:00.000, Oct 28 1984 02:00:00.000

16162.583587962963 16365.583599537036 //Apr 07 1985 02:00:00.000, Oct 27 1985 02:00:00.000

16526.583599537036 16729.583599537036 //Apr 06 1986 02:00:00.000, Oct 26 1986 02:00:00.000

16890.583599537036 17093.583599537036 //Apr 05 1987 02:00:00.000, Oct 25 1987 02:00:00.000

17254.583611111109 17464.583611111109 //Apr 03 1988 02:00:00.000, Oct 30 1988 02:00:00.000

17618.583611111109 17828.583611111109 //Apr 02 1989 02:00:00.000, Oct 29 1989 02:00:00.000

17982.583622685186 18192.583622685186 //Apr 01 1990 02:00:00.000, Oct 28 1990 02:00:00.000

18353.583634259259 18556.583634259259 //Apr 07 1991 02:00:00.000, Oct 27 1991 02:00:00.000

18717.583634259259 18920.583645833332 //Apr 05 1992 02:00:00.000, Oct 25 1992 02:00:00.000

19081.583645833332 19291.583657407409 //Apr 04 1993 02:00:00.000, Oct 31 1993 02:00:00.000

19445.583657407409 19655.583668981482 //Apr 03 1994 02:00:00.000, Oct 30 1994 02:00:00.000

19809.583668981482 20019.583668981482 //Apr 02 1995 02:00:00.000, Oct 29 1995 02:00:00.000

20180.583680555555 20383.583680555555 //Apr 07 1996 02:00:00.000, Oct 27 1996 02:00:00.000

20544.583680555555 20747.583692129629 //Apr 06 1997 02:00:00.000, Oct 26 1997 02:00:00.000

20908.583692129629 21111.583692129629 //Apr 05 1998 02:00:00.000, Oct 25 1998 02:00:00.000

21272.583703703705 21482.583703703705 //Apr 04 1999 02:00:00.000, Oct 31 1999 02:00:00.000

21636.583703703705 21846.583703703705 //Apr 02 2000 02:00:00.000, Oct 29 2000 02:00:00.000

22000.583703703705 22210.583703703705 //Apr 01 2001 02:00:00.000, Oct 28 2001 02:00:00.000

22371.583703703705 22574.583703703705 //Apr 07 2002 02:00:00.000, Oct 27 2002 02:00:00.000

22735.583703703705 22938.583703703705 //Apr 06 2003 02:00:00.000, Oct 26 2003 02:00:00.000

23099.583703703705 23309.583703703705 //Apr 04 2004 02:00:00.000, Oct 31 2004 02:00:00.000

23463.583703703705 23673.583703703705 //Apr 03 2005 02:00:00.000, Oct 30 2005 02:00:00.000

23827.583715277779 24037.583715277779 //Apr 02 2006 02:00:00.000, Oct 29 2006 02:00:00.000

24170.583715277779 24408.583715277779 //Mar 11 2007 02:00:00.000, Nov 04 2007 02:00:00.000

24534.583715277779 24772.583715277779 //Mar 09 2008 02:00:00.000, Nov 02 2008 02:00:00.000

24898.583726851852 25136.583726851852 //Mar 08 2009 02:00:00.000, Nov 01 2009 02:00:00.000

25269.583726851852 25507.583726851852 //Mar 14 2010 02:00:00.000, Nov 07 2010 02:00:00.000

25633.583726851852 25871.583726851852 //Mar 13 2011 02:00:00.000, Nov 06 2011 02:00:00.000

25997.583726851852 26235.583738425925 //Mar 11 2012 02:00:00.000, Nov 04 2012 02:00:00.000

26361.583738425925 26599.583738425925 //Mar 10 2013 02:00:00.000, Nov 03 2013 02:00:00.000

26725.583738425925 26963.583738425925 //Mar 09 2014 02:00:00.000, Nov 02 2014 02:00:00.000

27089.583738425925 27327.583738425925 //Mar 08 2015 02:00:00.000, Nov 01 2015 02:00:00.000

27460.583738425925 27698.583738425925 //Mar 13 2016 02:00:00.000, Nov 06 2016 02:00:00.000

27824.583738425925 28062.583738425925 //Mar 12 2017 02:00:00.000, Nov 05 2017 02:00:00.000

28188.583738425925 28426.583738425925 //Mar 11 2018 02:00:00.000, Nov 04 2018 02:00:00.000

28552.583738425925 28790.583738425925 //Mar 10 2019 02:00:00.000, Nov 03 2019 02:00:00.000

28916.583738425925 29154.583738425925 //Mar 08 2020 02:00:00.000, Nov 01 2020 02:00:00.000

29287.583738425925 29525.583738425925 //Mar 14 2021 02:00:00.000, Nov 07 2021 02:00:00.000

29651.583738425925 29889.583738425925 //Mar 13 2022 02:00:00.000, Nov 06 2022 02:00:00.000

30015.583738425925 30253.583738425925 //Mar 12 2023 02:00:00.000, Nov 05 2023 02:00:00.000

30379.583738425925 30617.583738425925 //Mar 10 2024 02:00:00.000, Nov 03 2024 02:00:00.000

30743.583738425925 30981.583738425925 //Mar 09 2025 02:00:00.000, Nov 02 2025 02:00:00.000