Hijri Committee of India (HCI) has been engaged in researching and propagating an Islamic Lunar Calendar, to be applied universally for the whole mankind, for the last 4 decades. During the last 19 years it has published a true Hijri Calendar which has dates exactly tallying with the phases of the moon, as directed in Noble Qur’an 2:189.
The Islamic calendar (or Hijri calendar) is a purely lunar calendar. It is the same astronomical Lunar Calendar and the month begins and ends on the conjunction day ( Astronomical new moon), which means conjunction is the last day of the month. Sometimes it is on the 29th day and sometimes 30th day. The calendar contains 12 months that are based on the Qur’an (Sura IX, 36-37). It is based on the motion of the Moon and its proper observance is a sacred duty for Muslims. Each phase of the moon and its angular distance indicates each Date as shown by a natural calendar hung in the sky. Sometimes we cannot see the moon because of the changes in weather. but it does not make any difference in calendar dates because it is related to the motion of the moon. Not its physical visibility. The astronomical new moon time and date already computed exactly for thousands of years backward and forward.