Sighting The Moon Crescent

Sighting the moon crescent
How is the first day of a month in the Lunar calendar determined?
You may think about so accurate softwares of these days and their predictions of the moon position of every time in every where! It is true,but there is another condition that the new month in Lunar Calendar starts, and this condition is just sighting the crescent of the young moon!
This action is most common on Islamic countries or lands which Lunar calendar is used.In Iran also there are some sites and people who work on it especially at the beginning of more important months like Ramadan and etc.
Observation of this fade,thin crescent is so hard and some times needs expert equipments and very fast time reaction(because moon is so close to fall under horizon!)There are some records for this action too!
Here is a photo of such a crescent(reference is here: http://www.flickr.com/photos/marubozo/5688570463/)

there is a question for myself:
If only seeing this crescent is the condition,how can we make sure that our equipments are strong enough to visit this valuable arc and there is a bug!because we can make these instruments as powerful as we want and maybe one day we can observe a crescent with our 30 inches telescope(!) that the other before days we just couldn't!so are the previous beginning of months wrong?!!:blink:

Seeking Thin Crescent Moon

Few celestial sights are as beautiful as a slender crescent Moon in the western evening sky, the day after it passes the Sun each month. A good-luck token for some, a bad-weather omen for others, it is also a sight that regulates the lunar calendar of the Muslim world

http://up.avastarco.com/images/a8du7fahlvak3g9jjx31.jpg


Photo by : Youssef M. Ismail

For amateur astronomers and photographers alike, each young Moon makes an inviting target. The sunlit part encircles the Moon’s night side, which is not fully dark but is bathed in sunlight reflected back toward the Moon from Earth. This earthshine theoretically gets brighter the closer the Moon is to new, except that it can easily be washed out by twilight. On rare occasions it has even been seen during a total solar eclipse


To get more information check this link

discussing about different ways of lunar crescent observing is an important .islamic subject which has ancient history in iran

also Its importance endures today, since the Hijra Lunar Calendar is still
organized according to the rules or criteria for lunar crescent visibility in
...different Muslim countries

thus I want to share a very good article in which will analyze two tables for determining lunar crescent visibility, included in al-Khāzinī’s Sanjarī Zīj


this article has been written with Hamid-Reza Giahi Yazdi & can be seen here

:thumbsup:

About six years ago, I and my colleagues wrote a book about lunar crescent sighting in Persian.
In the following text I have tried to introduce this book

New moon (Scientific Principles of Lunar Crescent Sighting
by Amir Hasanzadeh, Mohammad Ahmadi, Yoosef Shabani

http://img1.tebyan.net/big/1387/06/1...9544113100.jpg
In recent years we have witnessed good progress in crescent observation. But a major problem is lack of a scientific book in this field to guide observers and inform them well about this kind of observations. Solving this problem is the purpose of authors of this book.
The writers that are members of North Star Scientific Research Institute (www.NSSRI.ir) decided to write a book on principles of crescent observation. This book tries to increase society knowledge about crescent observation in scientific words.
The book has set up in 8 chapters in addition to attachments and pictures section. In the first chapter you can read about spherical astronomy that is prerequisite of other chapters. In chapters 2 and 3 moon’s structure and orbit are under discussion. In chapter 4 readers learn crescent observation’s terminology and in chapter 5 about lunar Hijri calendar. In chapter 6 and 7, records and crescent visibility criteria are comprehensively specified and in the last chapter how to observe a lunar crescent.
One of the attachments specifically talks about the islamic jurisprudence (Shia fiqh) of crescent observation which is Compiled and arranged by Dr. Alireza Movahednejad.

Islamic research Institute of Astan-e Qods -e Razavi (www.islamic-rf.ir) published it in 1387 SH (2008). This book published in 2011 for the second time.