Jakarta. The Religious Affairs Ministry has scheduled an isbat session — an official government meeting to determine the start of an Islamic lunar month, particularly Ramadan, Eid al-Fitr and Eid al-Adha — on Tuesday, to decide the beginning of this year's Ramadan, according to an announcement on the Directorate General of Islamic Community Guidance’s website.

The session will be chaired by Religious Affairs Minister Nasaruddin Umar and begin at 4 p.m. at the HM Rasjidi Auditorium at the ministry’s headquarters in Jakarta.

Director General of Islamic Community Guidance Abu Rokhmad said the government combines astronomical calculations (hisab) and moon sighting (rukyatul hilal) to determine the start of Islamic months.

“The isbat session reconciles astronomical data with moon-sighting results to ensure that the start of Ramadan is determined scientifically and transparently, while involving all relevant stakeholders,” Abu Rokhmad said in a statement carried by NU Online.

The session will include representatives from major Islamic organizations, including Nahdlatul Ulama (NU) and Muhammadiyah, as well as astronomers and experts from weather agency BMKG, research agency BRIN, the Jakarta Planetarium and several observatories. Senior ministry officials, members of House Commission VIII, the Indonesian Ulema Council and foreign ambassadors are also expected to attend.

According to the ministry’s 2026 Islamic calendar, Ramadan is projected to begin on Thursday, Feb. 19. The official start date, however, will depend on the outcome of the isbat session.

NU’s Position

Nahdlatul Ulama relies on direct moon sighting to determine the start of Islamic months, with the results incorporated into the government’s final deliberation.

Astronomical calculations show that the conjunction (ijtima) ahead of Ramadan will occur on Tuesday, Feb. 17, 2026, at 7:01 p.m. Jakarta time. At sunset, the moon’s position across Indonesia is projected to range between minus 2 degrees 24 minutes and minus 0 degrees 58 minutes, with elongation between 0 degrees 56 minutes and 1 degree 53 minutes.

The data indicate that the crescent moon does not yet meet the minimum visibility criteria adopted under the Brunei-Indonesia-Malaysia-Singapore (MABIMS) agreement, meaning the hilal is theoretically not visible.

To verify the calculations, the ministry will conduct moon sighting at 96 locations nationwide, while BMKG will deploy observation teams at 37 monitoring points.

NU has not issued a formal prediction but traditionally aligns with the government’s final decision. If the crescent is not observed, Ramadan could begin a day later.

Muhammadiyah’s Position

In contrast, Muhammadiyah applies astronomical calculations known as hisab hakiki wujudul hilal, which determine the start of the month based solely on the moon’s position without requiring physical sighting.

The organization has declared that 1 Ramadan 1447 H will fall on Wednesday, Feb. 18, 2026, according to a decree issued by its Tarjih and Tajdid Council. It has also set Eid al-Fitr for Friday, March 20, 2026.

Based on available astronomical data, Ramadan 2026 could begin on either Feb. 18 or Feb. 19, depending on the method applied. The government’s final decision will be announced following Tuesday’s isbat session.