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International Astronomical Center

Universal Hejric Calendar (UHC)


Last Updated 27 January 2007

In this page:-

Few Words about the UHC

The UHC is a Hejric calendar prepared by the "Crescents, Calendars, and Mawaqeet Committee" of the Arab Union for Astronomy and Space Sciences (AUASS), and it was adopted by the AUASS during the 2nd Islamic Astronomical Conference entitled (Astronomical Applications in Islamic Shari'a), held in Amman, Jordan in the period 29 - 31 October 2001. Where the second resolution of the conference’s resolutions stated:

"Use of the Universal Hejric Calendar (UHC), being introduced by the Arab Union for Astronomy and Space Sciences (AUASS) to the committees that calculate the calendars in the Islamic countries, because it is in agreement with the astronomical calculations and the sighting possibilities according to the Shari'a."

What is the UHC ?

The UHC divides the world into two major regions, which are:-

  1. Eastern Region: Extends from longitude 180 E to longitude 20 W.
  2. Western Region: Extends from longitude 20 W to western parts of the American Continents.

For each region, if the calculations for the crescent visibility on the 29th day of the Hejric month show that there is a possibility to see the crescent on that day from any location (land only) either by naked eyes or by optical aid (telescopes), then the next day is the first day of the new Hejric month.

What is the Visibility Criteria Adopted by the UHC ?

There are several crescent criteria to predict the crescent visibility, such as SAAO, Yallop, Odeh, …etc. UHC adopts Odeh Criteria.

To know more about the crescent criteria, please refer to any of these software; Accurate Times by Mohammad Odeh, or Moon Calculator by Dr. Monzur Ahmed.

Examples on the UHC

First Example:

The following graph shows the visibility of the crescent of Safar 1421 on 04 May 2000 using the program Accurate Times by Mohammad Odeh according to Odeh criterion.

For the Eastern Region: The graph shows that the crescent is visible by optical aid from western and southern parts of the African Continent, thus 05 May 2000 is the first day of Safar 1421 in the Eastern Region.

For the Western Region: The graph shows that the crescent is visible with difficulty by naked eyes from parts of South and North American Continents, thus 05 May 2000 is the first day of Safar 1421 in the Western Region.

Second Example:

The following graph shows the visibility of the crescent of Rabeea Thani 1428 on 17 April 2007 using the program Accurate Times by Mohammad Odeh according to Odeh criterion.

For the Eastern Region: The graph shows that the crescent is not visible anywhere within the region neither by optical aid nor by naked eyes, thus 19 April 2007 is the first day of Rabeea Thani 1428 in the Eastern Region.

For the Western Region: The graph shows that the crescent is visible with difficulty by naked eyes from parts of North American Continent, thus 18 April 2007 is the first day of Rabeea Thani 1428 in the Western Region.

Third Example:

The following graph shows the visibility of the crescent of Ramadan 1427 on 22 September 2006 using the program Accurate Times by Mohammad Odeh according to Odeh criterion.

For the Eastern Region: The graph shows that the crescent is not visible anywhere within the region neither by optical aid nor by naked eyes, thus 24 September 2006 is the first day of Ramadan 1427 in the Eastern Region.

For the Western Region: The graph shows that the crescent is not visible anywhere within the region neither by optical aid nor by naked eyes, thus 24 September 2006 is the first day of Ramadan 1427 in the Western Region.

Using UHC, Will All Countries Start The Hejric Month on The Same CIVIL Day ?

The answer is NO! It has just been made clear that some countries might start the month of Rabeea Thani 1428 for example on 18 April 2007, while others start it on 19 April 2007. But there will be never more than one civil day difference between any two countries.

Using UHC, Will All Countries Start The Hejric Month Within 24 Hours ?

Absolutely YES! Actually it is NOT important at all to start the same Hejric month in all countries on the same CIVIL day ! Do not forget that this is a civil day! They are us (the people) who agreed that the day starts at the hour 12 am and ends at 12 am! We shouldn’t stick on having the beginning of our Hejric month on the same civil day! There is no religious, reasonable or mental reason for this requirement! What might be important is that the whole Islamic countries start the same Hejric month within 24 hours (which is the definition of the day)!

What Are The Countries Which Adopt the UHC ?

Currently there are two countries adopt the UHC officially in their calendars, which are Jordan and Algeria.

UHC Tables (Eastern Region)

Kindly Click Here to view the UHC for the Eastern Region.

UHC Tables (Western Region)

Kindly Click Here to view the UHC for the Western Region.


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