Time Zones in Malaysia

Some years ago I created this page based on information from the file asia, which is part of the tz database. After giving a lecture on the Chinese calendar at the Department of History at the National University of Singapore I got in touch with Mok Ly Yng, who has researched this extensively, and corrected some errors in the tz database. I have created a page with the article he sent me. I have kept this page because it gives information about East Malaysia, too. I use the modern terms East and West Malaysia for convenience.

The local mean time in Kuala Lumpur is (6:46:48). West Malaysia used local mean time until 1880, when they changed to Singapore mean time (6:55:24). In 1905 they changed to 7:00, in 1933 to 7:20 and in 1941 to 7:30. During the Japanese occupation, Tokyo time was used, before changing back to 7:30 in 1945. In 1982, they finally changed to 8:00. This was done to create a single time zone for East and West Malaysia. Since the capital and 80% of the population is in West Malaysia, I've always found it strange that the whole country follows East Malaysia's time, but I guess it was a gesture of goodwill towards East Malaysia.

# Malaysia
# Zone  NAME            GMTOFF  RULES   FORMAT  [UNTIL]
Zone Asia/Kuala_Lumpur  6:46:48 -       LMT     1880
                        6:55:24 -       SMT     1905 Jun # Singapore Mean Time
                        7:00    -       MALT    1933     # Malaya Time
                        7:20    -       MALT    1941 Aug 31
                        7:30    -       MALT    1942 Feb 15
                        9:00    -       JST     1945 Sep 2
                        7:30    -       MALT    1982 May
                        8:00    -       MYT     # Malaysia Time

The local mean time in Kuching is (7:21:20). Sabah and Sarawak used local mean time until 1926. They then changed to 7:30. In 1933, when West Malaysia changed to 7:20, they changed to 8:00, with a 20min time change between September 14 and December 14. During the Japanese occupation, Tokyo time was used, before changing back to 8:00, but without the daylight savings time, in 1945. The tz database does not distinguish between Sabah and Sarawak, so I assume that these changes applied to both places.

Zone Asia/Kuching       7:21:20 -       LMT     1926 Mar
                        7:30    -       BORT    1933    # Borneo Time
                        8:00    NBorneo BOR%sT  1942
                        9:00    -       JST     1945 Sep 2
                        8:00    -       BORT    1982 May
                        8:00    -       MYT

# Rule  NAME    FROM    TO      TYPE    IN      ON      AT      SAVE LETTER/S
Rule    NBorneo 1935    1941    -       Sep     14      0:00    0:20 TS
Rule    NBorneo 1935    1941    -       Dec     14      0:00    0    -

The daylight savings time from September 14 to December 14 is very interesting. On November 3, the equation of time reaches a maximum of 16m 25s. This seems to be an attempt at reducing the variation in the time of the sunrise by looking at how the analemma rises in the tropics.


Helmer Aslaksen
Department of Mathematics
National University of Singapore
helmer.aslaksen@gmail.com

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