Rukyat hilal determination of the beginning of Shawwal will be carried out on 29 Ramadan 1443 H which falls on Sunday, May 1, 2022. How is the potential for seeing the new hilal at the beginning of the month of Shawwal 1443 H or Eid 2022 both globally?
Ijtima (conjunction) or the early new moon phase of Shawwal 1443 H falls on Saturday, April 30, 2022 at 20:27.57 Universal Time or Sunday, May 1, 2020 at 03.27.57 WIB.
Meanwhile, North and South America experience conjunction before sunset on May 30, 2022. Meanwhile, South Asia, East Asia, Southeast Asia, Australia and New Zealand experience conjunction the next day on May 1, 2022.
It can be seen that from the map above, the Moon is still below the horizon for eastern Canada, eastern Brazil, Suriname, French Guiana, Europe, Africa, Asia, Australia and New Zealand on the evening of April 30, 2022. As for North America and most of America South the elevation varies from -1 to +1 degrees.
Due to the low altitude of the Moon near the horizon, the Moon is difficult to observe either with or without tools even though it is already above the horizon, so it is possible that the new moon can be seen the next evening, on May 1, 2022.
From the map above, ijtima occurs after astronomical dawn/dawn in New Zealand. Seen from New Zealand, Papua New Guinea, Oceania, and a small part of Australia which has experienced sunrise at ijtima. Meanwhile, Chile and Argentina are experiencing a partial solar eclipse. A few hours later in the evening, the height of the hilal in Chile and Argentina is low enough even close to the horizon so that the possibility of the hilal is difficult to observe in both countries.
If ijtima occurs after astronomical dawn/dawn in New Zealand, then no country will meet the Moon's elevation of 5 degrees and the Moon-Sun elongation of 8 degrees. So, according to the criteria of the Global Islamic Calendar or the 2016 Istanbul Recommendation, 1 Shawwal 1443 H falls on Monday, 2 May 2022.
From the map above, it can be seen that most of Southeast Asia, Japan, Korea, China meet the geocentric elongation (measured from the center of the Earth) of 6.4 degrees. However, the area has not met the topocentric elongation (measured from the Earth's surface) of 6.4 degrees. China meets the geocentric elongation of 8 degrees for the entire region, but has not met the topocentric elongation of 8 degrees for the northwestern regions such as Urumqi/Xinjiang.
Most of Central Asia and South Asia have met the geocentric elongation of 8 degrees, but the entire area of Central Asia and South Asia has not met the topocentric elongation of 8 degrees. The Middle East, Europe, and Africa (excl. South Africa) have met the topocentric elongation of 8 degrees. Even some areas such as western Africa, Portugal, and Spain have met the geocentric elongation of 10.5 degrees (though it has not met the topocentric elongation of 10.5 degrees), so there is a possibility that the new moon can be observed without using tools in these areas.
The regions of North America and South America have fulfilled the elongation of 10.5 degrees both geocentric and topocentric. So that the possibility of the new moon can be observed without the use of tools in the region, although the height of the new moon in Chile and Argentina varies between 2 to 8 degrees. Based on these considerations, 1 Shawwal 1443 H in most areas of the world will fall on Tuesday, May 2, 2022.
However, some countries in Southeast Asia and South Asia may celebrate holidays differently from the rest of the world. The following is an elongation contour of 6.4 degrees for four conditions: (a) Topocentric at sunset, (b) Topocentric at best time of observation (=Sunset +4/9 x length of Moon above the horizon), (c) Topocentric when The moon is setting, and (d) Geocentric at sunset:
Based on the map above, in condition (a) the 6.4 degree elongation contour does not pass through Sabang but rather the Great Nicobar Island in Kep. Nicobar, India. This line then passes through Myanmar, China, Mongolia, and Russia, so that all of Indonesia does not actually meet the topocentric elongation of 6.4 degrees at sunset. A few minutes later, in condition (b) the 6.4 elongation contour intersects the northwest part of Aceh Province, so that areas such as Sabang, Banda Aceh, and Aceh Besar have met the topocentric elongation of 6.4 degrees at the best time of observation.
When the moon sets, in condition (c) the elongation contour of 6.4 degrees passes through Mount Sitoli, Sibolga, to Tebing Tinggi. Later, this line passes through Thailand (shifts to the East), China, Mongolia, Russia. So that the entire province of Aceh and most of the province of North Sumatra (including the city of Medan) have fulfilled the topocentric elongation at sunset.
Thus, a topocentric elongation of 6.4 degrees can be achieved in the northwestern part of Indonesia (such as Aceh and North Sumatra) after sunset to sunset. However, other countries in Southeast Asia such as Malaysia, Brunei, Singapore, the Philippines, Vietnam, Laos, and Cambodia do not meet the topocentric elongation of 6.4 after sunset to sunset. So, it is possible in these countries to set 1 Shawwal to fall on Tuesday, May 3, 2022.
When the sun sets, in condition (d) the elongation contour of 6.4 divides the island of Sulawesi to the border of West Nusa Tenggara and East Nusa Tenggara. Thus, for the regions of Sumatra, Java, Kalimantan, Bali, West Nusa Tenggara, and West Sulawesi, the geocentric elongation is 6.4 degrees. Likewise for other countries in Southeast Asia such as Malaysia, Brunei, Singapore, the Philippines, Vietnam, Laos, Cambodia, Thailand, Myanmar, which have met the geocentric elongation of 6.4 degrees. This 6.4 degree contour also passes through China, Korea, Japan, so that if both countries observe the new moon independently (not following the MABIMS decision), then both countries have met the geocentric elongation of 6.4 degrees.
"So, actually all of Southeast Asia can celebrate on Monday, May 2, 2022, as in most regions in the world.