Eid ul-Fitr (Hari Raya Puasa) was celebrated in Singapore on January 8 2000.
To see why this did not correspond to an actual sighting, you can consult Ramadhan & Eid ul-Fitr 1420AH (1999/2000) by Dr. Eid ul-Fitr (Hari Raya Puasa) was celebrated in Singapore on 27 December 2000.
This is done in India, Pakistan, Bangladesh and the US.
In 11 years of this cycle, Dhū al-Ḥijjah has 30 days, and in the other 19 years it has 29. No months are intercalated, so that the named months do not remain in the same seasons but retrogress through the entire solar, or seasonal, year (of about 365.25 days) every 32.5 solar years.MUIS (Majlis Ugama Islam Singapura), the Islamic Religious Council of Singapore, then decided that the new month starts if at sunset on the eve of the 29th day the Moon is above the horizon.(The Muslim calendar in Singapore is based on latitude 1 20' 34'' N and longitude 103 51' 08'' E.) In the 80s they decided to follow a variation of the 1978 Istanbul criteria and require that the altitude of the Moon should be more than 5 degrees at sunset. This was part of an attempt to coordinate the major holidays with Malaysia, Brunei and Indonesia, which occasionally may lead to different results.However, it is common among Sevener Shi'ites (Isma'ili), including the Bohras (Musta'lis) and Nizaris (Isma'ili Khojas, Aga Khanis).It seems to have been designed to be closer to new Moon than to the first visibility of the lunar crescent, so it often runs a day or two ahead of the regular Islamic calendars.There are currently about one million Bohras and about 15 millions Nizaris, compared to over a billion Sunnis and close to a hundred million Twelver Shi'ites.