VISIBILITY OF NEW LUNAR CRESCENT FOR RAMADAN

on year 1431

Done by :Amar Yahya Yahya al-Ansi

Assistant Teacher,Physics Dept., Faculty of Science, Sana’a Univ.

amar_1984_11@hotmail.com

Sunset and Moonset on 10/8/2010

Note: The moon near to the sun and width of the lunar crescent isn’t clearly

Sunset and Moonset on 11/8/2010

Note:Moon away from the sun and width of the lunar crescent is clearly

The criteria for the visibility of the new lunar crescent

THE ANCIENT METHODS:

The Muslim/Arab astronomers criterion :this criterion depends on1- Lag time of the Moon ( Lag ) is the interval time between sunset and moonset , where Lag should

be more than 48 minutes.2- Altitude of the moon is the arc distance measured from the moon to the horizon , where the

altitude of the moon should be more than 8° at sunset.

THE MODERN APPROACH

Yallop criterion :This criterion depends on a parameter ‘q’, where ‘q’ is derived from the relative geocentric altitude of

the moon and the topocentric crescent width at ‘best time’, i.e. sunset time + (4/9) moonset lag.

q > +0·216Easily visible (ARCL ≥ 12°)

+0·216 ≥ q > -0·014Visible under perfect conditions

-0·014 ≥q > -0·160May need optical aid to find crescent

-0·160 ≥ q > -0·232Will need optical aid to find crescent

-0·232 ≥q > -0·293Not visible with a telescope ARCL ≥ 8·5°

-0·293 ≥qNot visible, below Danjon limit, ARCL ≥ 8°

by using “Redshift 7 Premium ” software . It’s find out the various important quantities like the altitudes of the moon, the sun-moon elongation,etc.,

10/8/201011/8/2010

Sunset Time06:28:00pm06:27:00pm

Moonset Time06:41:00pm07:28:00pm

Best Time06:33:47pm06:54:7pm

Lag00:13: 0001:1:00

Altitude1°11'52.6"13°41'38.6"

ARCL7°53'25.69"20°57'1.44"

q-value-0.87850.23655

Arc of light (ARCL): The angular separation (elongation) between the Sun and the Moon.

On 10/8/2010

The Muslim criterion :The Muslim criterion : Lag =13min<45minLag =13min<45minAltitude= 1°11'52.6 "<8°Altitude= 1°11'52.6 "<8°hence, the moon is not visible on 10/8/2010, according to this criterion

Yallop criterionYallop criterion : :q= -0.8785<-0.293q= -0.8785<-0.293ARCL=7°53'25.69"≥8°ARCL=7°53'25.69"≥8°Not visible, below Danjon limit, ARCL ≥ 8°

On 11/8/2010

The Muslim criterion :The Muslim criterion : Lag = 61min >45minLag = 61min >45minAltitude= 13°41'38.6" >8°Altitude= 13°41'38.6" >8°hence, the moon is visible on 11/8/2010, according to this criterion

Yallop criterionYallop criterion : :q= 0.23655 >0.216q= 0.23655 >0.216ARCL= 20°57'1.44" ≥12°ARCL= 20°57'1.44" ≥12°Easily visible (ARCL ≥ 12°)

we know that each month beginning with the first sighting of the new moon. it means that the moon is visible on the evening of 11/8/2010 and not 10/8/2010.

Thus , we can see visibility of new lunar crescent for ramadan month. i.e. ramadan month will beginning on 11/8/2010

Thank you for your read

I wish I hear good news for you

I hope good month for you

Best wishes

Thank you for your read

I wish I hear good news for you

I hope good month for you

Best wishes