“The rukyatul hilal is carried out in the afternoon and the detection of the crescent moon is done after the sun sets. The crescent moon that appears after the sun sets is called hilal,” The Director of Bosscha Observatory, Dra. Premana W. Premadi, Ph.D., said in a press release received by ITB Public Relations Office.

The hilal observation will be done using 2 refractor telescopes, which are the 106 mm and 66 mm telescope. Each telescope is equipped with a CCD-based camera detector. The image captured by the camera is then processed using an image processing device to display the appearance of the crescent moon.

“The observation activity is done internally and only attended by the staffs at Bosscha Observatory. This is done to avoid the involvement of too many people at the same location,” Premana said. However, the people who are interested in the hilal observation process can watch it online via live streaming on the official Youtube Channel Observatory at the 22nd and 23rd of May, which starts at 15.30 WIB.

As an educational and research institute in the field of astronomy, the Bosscha Observatory of Institut Teknologi Bandung carries out observations of the crescent moon almost every month. Each year, the Bosscha Observatory is also used as one of the references to determine the start of Ramadhan and Shawwal for the public and the Ministry of Religious Affairs in Indonesia.

In Indonesia, the authority to determine the beginning of Ramadan and Shawwal is the government of the Republic of Indonesia through the process of itsbat trial. The task of the Bosscha Observatory is to deliver the results of calculations, observations, and research on hilal to the relevant government units if needed as input for the itsbat trial. The public can access the observations and data of the hilal on the Bosscha Observatory website https://bosscha.itb.ac.id.

Reporter : Adi Permana

Translator : Verdyllan Nurendra Agusta