Explanation - Why Ramadan 2013 should start on 9^th July 2013 in some countries and why on 10^th July 2013 in the rest of the world

We recall to the visitor our methodology for calculating the beginning of the month for determining the calendar for Makkah.
After the new moon is born, we first look for the earliest crescent in the evening sky of Makkah. If it is visible, then the new month starts the next day. If not, we look further and further west until the time of fajr in Makkah. If the crescent is visible anywhere to the west before fajr in Makkah, then the new month starts on the next day, exactly as if the crescent had been visible in the evening in Makkah itself. We call this concept that of extended visibility.

The methodology for calculating the beginning of the month in Makkah can be applied to any place on earth. The month will begin next day if: (1) the new moon is born (2) if the young crescent is visible in the evening sky of the place considered, or (3) if it is visible at somewhere to the west of the place before fajr there. Otherwise the month will last a day longer.

We follow this methodology in order to determine the beginning of important Islamic dates for the various countries of the world. For several strategically chosen countries on different continents we choose a town towards the eastern limit of the country. We choose the eastern limit because fajr in the east is earlier than fajr in the west. If visibility is acquired for the east, then it will also be acquired for the west where fajr is even later. We avoid situations where there is visibility for the west but not for the east, because in such cases, the country will be divided into two for celebrating the feast day. For most countries, such a situation will not be acceptable.

The visibility curves

We now invite the reader to consult the visibility curves for the beginning of Ramadan 1434 (Ramadan 2013). Two visibility curves are pertinent: that of 8^th July 2013 and that of 9^th July 2013 (Ramadan 2013 Visibility Curves). The new moon is born on 8^th July 2013 at 07 hours 15 minutes Universal Time. The blue and green zones represent the areas of the world where the crescent can be seen with the naked eye, blue under good atmospheric conditions, green representing easy visibility.

The visibility curve for 8^th July 2013 shows most of the earth in a non visibility zone. Thus there will be no direct sighting on the various continents. However, a blue zone covers a part of the Pacific Ocean towards the west. Thus it becomes essential to calculate whether fajr in some countries – with no direct visibility on the evening of 8^th July 2013 – is not before the visibility of the crescent in the Pacific ocean, thus insuring visibility to the west of the country under consideration, before fajr in the country. These countries can thus start the fasting of Ramadan on 9^th July 2013.

For the other countries the visibility curve for 9^th July 2013 will apply. Here most of the world is in a green or blue zone, specially in the southern hemisphere. Thus all countries which cannot start Ramadan 2013 on 9^th July 2013 will start fasting on 10^th July 2013.

The choice of the point of visibility

For calculating the visibility limit for countries in the first category, i.e. those that will start fasting on 9^th July 2013, the choice of the point of visibility in the Pacific Ocean is important. An observation of the visibility curve for 8^th July shows that the first point of visibility in the blue zone is situated at latitude 30° S and longitude 145° W. This point is in the ocean. However it corresponds to a real possibility – and not a theoretical or supposed possibility – of observing the new crescent.

In the Sharia, testimony to the sighting of the young crescent is capital. We follow this tradition strictly. Whenever possible, we ask reliable persons – astronomical observatories or groups of astronomers in different parts of the world – to photograph the new moon for us, according to the predicted visibility in the visibility curve of the month. The photo gallery on our site is witness to the reliability of our predictions and the exactness of our calculations. Month after month, we publish photographs of the youngest possible crescent. We might point out that these photographs have been taken without any optical aid.

The best time of visibility for the new crescent

In his paper “A Method for predicting the first sighting of the New Crescent Moon”, the British astronomer B. D. Yallop gives the following formula for determining the best time for sighting the new moon after sunset in a given place (HM Nautical Almanac Office NAO, NAO Technical Note, Updated April 1998) :
Best time of visibility of the new moon = Sunset time + 4/9 * (Difference between sunset and moonset time)
Let us now examine the situation after birth of the new moon (conjunction) on 8^th July 2013 at 07H15M Universal Time (UTC) at the first point of visibility at 30° S and 145° W :
We choose as time of reference for the observation of the young crescent at 30° S 145°W, 03H16M on 9^th July 2013 in universal time UTC (remember that, in approximate local time, it is 17H16M on 8^th July 2013). If, in the cities we have chosen as points of reference, the time of fajr in UTC is after 03H16M Ramadan will start on 9^th July 2013. Otherwise it will start next day.

For a more immediate understanding, we have given the comparison between the time of fajr in the selected cities and that of the best time of observation in the Pacific ocean in local times and not in UTC.

The results
Once the place and time of visibility were determined, we chose 16 strategically situated cities in Africa and Europe and 7 in the Americas and two in Asia.
The results of the calculation are reproduced in the following table.



We invite the reader to carefully study this table. The columns are self-explanatory. The fifth and sixth columns compare the fajr times in the cities under consideration with the best time of visibility at the point of observation, both expressed in the local time of the concerned city. If these fajr times are after the time of visibility of the new moon in the Pacific ocean, then Ramadan will start on 9^th July 2013. Otherwise it will start next day. The last two columns explain this.

List of cities and map

We have used these results to establish a list of countries according to the date of the beginning of Ramadan 2013. The reader can consult this table by clicking here.
For the facility of the reader, we have also provided a map with markers of different colours for countries which start Ramadan on 9^th July 2013 and those that do so next day.

Conclusion
The concept of extended visibility to the west of a place before fajr in the place has allowed us to publish the dates of the beginning of Ramadan 2013 for various countries. In future we intend to integrate this concept of extended visibility in our visibility curves themselves. This will lead us to an authentic, legitimate and rigorously exact calendar for all places in the world.