When is 1 Ramadan 1445 H? This is BRIN and BMKG's prediction

Jakarta, CNBC Indonesia – Indonesia will soon welcome the fasting month. A number of institutions have also provided predictions about when 1 Ramadan 1445 Hijiah will start.

The National Research and Innovation Agency (BRIN) predicts that 1 Ramadan 1445 Hijri will fall on Tuesday, March 12 2024. This forecast is based on the new criteria for 1 Ramadan which was agreed in 2021.

Lead Expert Researcher at the BRIN Space Research Center, Thomas Djamaluddin, explained that the Ministers of Religion of Brunei, Indonesia, Malaysia and Singapore (MABIMS) had agreed on new criteria for determining Ramadan.

Based on the results of the 2021 agreement, the criteria for the crescent moon have changed to a height of 3 degrees and an elongation of 6.4 degrees. This agreement was marked by the signing of a joint letter ad referendum in 2021 regarding the use of the new MABIMS criteria in Indonesia starting in 2022.

“At the end of the month of Sha'ban 1445 AH or March 10 2024, the height of the Moon in Indonesia is less than 1 degree. On the island of Java, such as Jakarta, it is 1.7 degrees, which does not meet the MABIMS criteria,” said Djamal when talking about the 'New MABIMS Criteria in Determining the Beginning of Ramadan at the BJ Habibie BRIN Building, Central Jakarta, quoted from secSunday (10/3/2024).

He explained that this forecast meant there would be differences in terms of the start of Ramadan in Indonesia. However, he emphasized that the differences were not caused by differences in methods.

In determining the start of Ramadan, there is the rukyatul Hilal method (observation) and the reckoning method (calculation). These two methods are often cited as the cause of differences even though they are not at all.

“Hisab and rukyat are used in determining the start of Ramadan. When differences occur later, oh this is because there are mass organizations that use hisab, there are mass organizations that use rukyat, actually not. In astronomy, hisab and rukyat are in line or equal so they can be reconciled. One of them is not more common compared to others,” explained Djamal.

Djamal explained that the differences were generally caused by many factors. However, the root of the problem is due to differences in criteria. According to him, there are three things needed for an established calendar system.

“The calendar requires three things, whatever the calendar, the Gregorian calendar, the Javanese calendar, the Hindu calendar, etc., requires three things to become an established calendar that can be mutually agreed upon: there is a single agreed criterion, there is an agreed territorial boundary, there is an authority single person who manages it,” he said.

BMKG projection

The Meteorology, Climatology and Geophysics Agency (BMKG) also provides information on Hilal data (Hisab results) at sunset, which can be used in carrying out Hilal Rukyat (Observations).

Following are the complete results of the BMKG analysis regarding the Hilal forecast for the start of Ramadan 2024.

Conjunction Time (Ijtima') and Sunset

Geocentric conjunction or conjunction or ijtima' is an event when the ecliptic longitude is. The Moon is the same as the ecliptic longitude of the Sun and the observer is assumed to be at the center of the Earth.

This event will occur again on Sunday, March 10 2024 AD, at 09.00.18 UT or 16.00.18 WIT or 17.00.18 WITA or 18.00.18 WIT, namely when the ecliptic longitude of the Sun and Moon is exactly 350.280 degrees .

Astronomically, the implementation of rukyat Hilal determines the beginning of the month of Ramadan 1445 H for those who apply rukyat in determining it is after sunset on the 10th for those where the conjunction occurs before sunset, and March 11 2024 for those whose conjunction occurs after sunset.

Meanwhile, for those who apply reckoning in determining the start of Ramadan 1445 H, it is necessary to take into account the reckoning criteria at sunset on March 10 and 11 2024.

Other Astronomical Objects That Have the Potential to Confound Rukyat Hilal

In planning the Hilal rukyat, it is also necessary to estimate astronomical objects other than the Hilal and the Sun whose position is close to the Moon and whose light is not much different from the Hilal or brighter than the Hilal. This astronomical object can be a planet, for example Venus, Mercury, or a bright star such as Sirius. And the existence of other astronomical objects has the potential to make observers consider them Hilal.

According to BMKG, on March 10 2024, the Moon sets before the Sun sets, so data on other astronomical objects is no longer needed.

As for March 11 2024, from sunset to moonset there is another astronomical object whose angular distance is smaller than 5 degrees from the Moon, namely Mercury.

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