BRIN Researcher Predicts Start of Ramadan on 19 February 2026: Here's the Explanation
A researcher at the National Research and Innovation Agency (BRIN) has predicted that the start of Ramadan 2026, or 1447 Hijriah, in Indonesia could differ depending on the method used. BRIN’s analysis indicates that 1 Ramadan is predicted to fall on 19 February if local hilal (crescent moon) observations are applied.
The prediction was delivered by Prof Thomas Djamaluddin, Coordinator of the Astronomy and Observatory Research Group at BRIN’s Space Research Centre. Thomas explained that the discrepancy in determining the start of Ramadan this year stems from the difference between global and local hilal observations.
“This time the difference is unlike previous occasions, which arose from methodological differences (hisab versus rukyat) or differing criteria (Wujudul Hilal versus Imkan Rukyat). This time, the difference is between global hilal and local hilal,” Thomas told reporters on Tuesday (17 February 2026).
Thomas explained that the global hilal refers to the fulfilment of the Imkanur Rukyat criteria anywhere in the world. At maghrib (sunset) time on 17 February, this criteria would be met in Alaska. Consequently, users of the Unified Global Hijri Calendar (KHGT) would set the start of Ramadan at 18 February 2026.
“The global hilal refers to the fulfilment of the Imkan Rukyat criteria anywhere in the world. At maghrib on 17 February, this criteria is met in Alaska, so users of the Unified Global Hijri Calendar set the start of Ramadan at 18 February 2026,” Thomas said.
Meanwhile, Thomas noted, the local hilal refers specifically to the Indonesia and Southeast Asia region. At maghrib on 17 February, the position of the hilal would not yet meet the Imkanur Rukyat criteria, and in Indonesia the moon would still be below the horizon.
“The local hilal refers to the Indonesia and Southeast Asia region. At maghrib on 17 February, the position of the hilal does not yet meet the Imkan Rukyat criteria — in fact, in Indonesia the moon is still below the horizon,” he said.
Therefore, the start of Ramadan falls on 19 February 2026 when based on local hilal observations. The official determination of the start of Ramadan would await the results of the isbat session announced by the government.
“So by hisab calculation and (later to be confirmed) by rukyat observation, the start of Ramadan is 19 February 2026,” he said.
According to the Ministry of Religious Affairs’ Directorate of Islamic Community Guidance website, the isbat session to determine the start of Ramadan 2026 was to be held on the same day at Hotel Borobudur in Central Jakarta. The session was scheduled to begin at 16:30 Western Indonesian Time (WIB).
The proceedings would commence with a seminar on the hilal’s position at 16:30 WIB, followed by the isbat session proper at 18:30 WIB, and the announcement of results via a press conference at 19:05 WIB.
Hilal observations were to be conducted at various locations across Indonesia, from Aceh to Papua, involving regional teams and volunteer crescent moon observers.