GUIDE TO SIGHTING THE HILAL (CRESCENT MOON)

Bismillah hir-Rahman nir-Rahim

(In the name of ALLAH, THE MOST BENEFICENT, THE MOST MERCIFUL)
THE MUSLIM STUDENTS' ASSOCIATION (MSA) of COLUMBIA UNIVERSITY
102 Earl Hall, Columbia University, NEW YORK, N.Y. 10027
GUIDE TO SIGHTING THE HILAL (CRESCENT MOON)

1 Jan 1997

Dr. Mohibullah N. DURRANI
E-Mail: mnd0@columbia.edu
Web Page: http://www.Hilal-Sighting.Com
Copyright 1987-97
Permission Granted to all for free distribution

Muslim Students Association
Islamic Amateur Astronomers Association
102 Earl Hall, Columbia University
NEW YORK, N.Y. 10027

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
====================================================================
PLEASE FILL OUT THE QUESTIONS IN THE QUESTIONEER SECTION EVERY MONTH
====================================================================
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

INFORMATION ON CRESCENT MOON SIGHTINGS AND HINTS
The following information would help to prepare individuals who are interested in sighting the Crescent Moon (Hilal).

Please do remember to fill the information requested in the seperate file AND SUBMIT TO THE LOCAL ISLAMIC CENTER, so that the local Islamic Center can maintain records of Hilal Sighting, EVERY MONTH.

We also request that a copy be mailed to us at:
The Muslim Students' Association of Columbia University,
102 Earl Hall, NEW YORK, NY 10027, USA, and to:
The Islamic Societies of North America (ISNA) at
Post Office Box 38, PLAINFIELD, Indiana, 46168, U.S.A.
The info can also be e-mailed to: mnd0@columbia.edu)

On an evening previous to the Moon Sighting evening, it is advisable to FIND A PLACE WITH A CLEAR WESTERN HORIZON (i.e. without any buildings or trees obstructing the place where the sun sets, on the western horizon).
SET YOUR WATCHES to the correct time given by a time service (usually through calling a telephone number).
FAMILIARIZE YOURSELF WITH THE QUESTIONS ON THE REPORT and keep a copy in a file, for each month, with the local islamic center. Mail a copy to the Islamic Societies of North America (ISNA) at Post Office Box 38, PLAINFIELD, Indiana, 46168, U.S.A.
It should be noted that the actual PLACE OF THE SETTING SUN varies with the seasons. In the northern hemisphere, the sun sets to the north of west during the summer with the extreme north setting on the summer solstice (June 22). The sun sets due west on the autumnal equinox (Sept 22). The sun sets south of west during the winter with extreme south setting on the winter solstice (Dec 22). The sun again sets due west on the spring equinox (March 21). In the southern hemishpere, the directions from west are changed. During the southern summer (when it is winter in the northern hemisphere) the sun sets south of west.
Observe and note down the approximate angle of inclination of the PATH OF THE SUN while it is setting. This inclination of the path of the setting sun from the vertical is nearly equal to the latitude of the observing location.
TO SEEK THE CRESCENT MOON. In order to obtain an idea as to approximately where to look, the following information on LUNAR ORBIT is useful.
1. The PATH OF THE CRESCENT MOON while it is setting will be nearly parallel to the path of the setting Sun. The path of the Moon will be CLOSE to the path of setting Sun, being at a maximum of about 5 degrees (usually it is less than the +/- 5 deg) `above' or `below' the path of the sun, when observed from the surface of the earth. (See Figure A.)
2. The CRESCENT MOON will also be TRAILING the SUN by about 5 to 20 degrees, for a particular observing point. The earliest sightings in the world would have the moon trailing the sun by the least angle. The Trailing angle of the Moon from the Sun can be estimated from the Orbital details and the location of the observer.
3. The DURATION OF THE FIRST SIGHTINGS of very young moons may begin as early as 10 minutes after the sun has set (to allow the twilight to reduce in spectral intensity) with the first sightings being usually before 20 minutes after sunset and the sighting could continue for about 40 to 90 or more minutes after sunset. The sighting would finally be `fading' when the crescent is a few degrees above the horizon. The fading is due to atmospheric extinction caused by absorption. In order to isolate the Crescent from twilight glare it is helpful to have any hollow tube and to search for the crescent while looking through the tube. (See Figure B.)
4. The HORNS OF THE CRESCENT MOON (i.e. the ends of the approximately less than semi-circular arc of the Crescent) will always point in a direction approximately opposite to the location of the sun, the sun already being below the horizon. (See Figure C.)
5. A general rule for MEASURING ANGLES in the sky is as follows: When our hand is stretched out in front of us (hand facing the sky)
```
        
a. each finger at arm's length would cover about 1.5 deg at our eye,
b. two fingers             "                     3.0 deg     "
c. four fingers            "                     6.0 deg     "
d. closed fist             "                    10.0 deg     "
e. outstretched fingers    "                    20.0 deg     ".
   (See Figure D.)
```

****************************************************************************

`APPARANT SIGHTINGS', HONEST AND SINCERE `MISTAKES'

Of course, the Crescent Moon has to set and not appear to `rise' in the western horizon. A WISP OF CLOUD, which happened to be lit by the sun which has already set, could easily be mistaken for a crescent. This apparant `crescent' of cloud would travel with the prevailing winds and would not set in a path nearly parallel to the path of the setting sun. It could `rise' instead of set or may travel north-east or south-east insted of setting in the west.
REFLECTIONS from high-flying aeroplanes. These reflections of the sun on aeroplanes would not have the semi-circular arced shape of the crescent and the probability of their path being close to a lunar path is minute. The reflections could disappear while still being high up on the horizon.
MOMENTARY VISIBILITY of the crescent. It might appear that the crescent was `visible' for a moment by a single Shahid (witness). A crescent would always be visible for at least 5 minutes (if unobstructed by clouds, etc.) and hence should be again visible by the person first seeing it, and should be able to be seen by others in a group, when pointed out. All should examine the crescent carefully and try to ascertain its path and the direction of its horns. A note should be made of the time of sunset, time when the crescent was first visible and again the time when the crescent faded away near the horizon. The vertical angular height, which is the altitude of the moon should also be noted at these times. The vertical angular distance, which is the altitude of any heavenly body, is measured from the horizon.

        
 ****************************************************************************
  
				FIGURES
				*******
  
	    FIG.A: PATH OF THE MOON RELATIVE TO THE PATH OF THE SUN
	    *******************************************************
	(THIS DIAGRAM IS FOR A TYPICAL PLACE IN THE NORTHERN HEMI-SPHERE,
	 IN THE SOUTHERN HEMI-SPHERE, THE PATH SLOPES DOWN AND LEFT.)
 
 
	   \      \
	--) \      \ (--------- Max. angular separation
	     \      \           +/- 5 deg (moon-sun paths)
	      \      \   P                      
	       \      \   A                     
		\      \   T                       
		 \      \   H                   
	      P   \      \                      
	       A   \      \
		T   \        ((      CRESCENT   (HILAL)
		 H   \      ((       MOON   --------------------------------
		      \      \\  //                                       ^
		   O   \       ==   (if moon's path is                    |
		    F   \           `above' sun's path)                   |
			 \                                                |
		      S   \    | \   O                                     
		       U   \   |  \   F                                   A
			N   \  |   \                                      L
			     \ |    \   M                                 T.
			     /\      \   O                                 
			    // \      \   O                               D
 (90 - LATITUDE) =~ ANGLE of    \      \   N                              I
  (= COLATITUDE)   Inclination | \      \                                 F
		       //      |  \      \                                F.
	 ========================= \ ================================
	  WESTERN              |    \                        HORIZON      |
			       |     \                                    |
			       |                                          |
			       |        \/  SUN                           v
			       |     --(@@)--     --------------------------
			       |        /\  SUN
			       | (has already set)
			       |         
			       |         |
			 -----)|         |(-----
			       | AZIMUTH |
				DIFFERENCE
				BETWEEN THE
				MOON & SUN
				 
 
			FIG.B: ALTITUDE OF MOON AT SUNSET
			*********************************
 
					  )
					   )) CRESCENT
					  ))  MOON
					))
				      )
				  /
				/
			      /
			    /
			  /
			/\    Angle of Height of Moon, above Horizon
		      /    \  = Altitude of Moon
		  ( )  -----------------------------------------    \/  SUN
		   |  /         HORIZON - HORIZONTAL             --(@@)--
		   |/                                               /\  SUN
		   |-----                                     (has just set)
		   |
		   |
		  / \
		/     \
	______________________________________________________
	//////////////////////////////////////////////////////
	GROUND  GROUND  GROUND  GROUND  GROUND  GROUND  GROUND
 
	Height (degrees) of first sighting:
	Height (degrees) of last sighting (fading) or moonset:
 
	The heights (altitudes) of the crescent are to be noted not 
	only when it is first sighted, but also when it fades while 
	it is going lower in the sky, since the crescent could sometimes 
	fade away - due to atmospheric opacity - even before it sets in 
	the western horizon.
 
 
		FIG.C: ORIENTATION OF ENDS OF CRESCENT  
		**************************************
			AND ITS CURVATURE
 
	The orientation of the Crescent is reported with reference to an
	imaginary clock on the western horizon:
 
		    IMAGINARY CLOCK ON WESTERN HORIZON
 
				12 'O Clock
				    |
				   ___
				 (     )
		9 'O Clock  --  (       )  --  3 'O Clock
				((     ))  ----- HILAL (Crescent),
				   ===           Shown from 4 through 6
				    |            to 8'O Clock position,
				6 'O Clock       Double-Lines  
 
 
  CRESCENT 1:                   CRESCENT 2:                     CRESCENT 3:
 
    (                                                                  )
   (                                                                    )
    (                           (          )                           )
      (                           __    __                           )
				     ==
 From:  7 'O Clock            From:  4 'O Clock             From:  2 'O Clock
 To:   10 'O Clock            To:    8 'O Clock             To:    5 'O Clock
 
	Note: The Crescent orientations could be anywhere from around 
	the 2 'O Clock position to the 10 'O Clock positions.  
	The actual extent (length) of the crescent would 
	usually be less than 180 degrees, i.e.
 
	2-7    (this would be 150 deg), 
	3-9    (this would be 180 deg), 
	4-9:30 (this would be 165 deg), 
	5-9:30 (this would be 135 deg) etc.
 
	
		FIG.D: MEASURING APPROXIMATE ANGLES IN THE SKY
		**********************************************
	
	a. each finger at arm's length would cover about 1.5 deg at our eye,
	b. two  fingers            "                     3.0 deg     "
	c. four fingers            "                     6.0 deg     "
	d. closed fist             "                    10.0 deg     "
	e. outstretched fingers    "                    20.0 deg     ".
	
			  ---)| |(---  1.5 deg for each finger.
		  ( )          |   
		   |           |
		   |-----------
		   |
		   | 
		   |
		  / \
		/     \
	______________________________________________________
	
    
    Angle        3.0 deg        6.0 deg           20.0 deg  to thumb
    Distance --)|  |(--     --)|    |(--     --)|      |(--
      
      Fingers )) ||             ||||             __\||/   (( Fingers
      Palm   ))  ||              ||                 ||    (( Palm
      Wrist ))  ----            ----               ----   (( Wrist

  No.of Fingers: 2 fingers      4 fingers       4 outstretched fingers and
  
    
 ****************************************************************************
 ****************************************************************************
 ****************************************************************************
 
	 APPROXIMATIONS TO DIRECTION OF KA'BA (MAKKAH Saudi Arabia)
	 **********************************************************
   
	In most places of the UNITED STATES of AMERICA, an APPROXIMATION 
	to the direction of KA'BA, to determine the DIRECTION OF SALAT 
	(PRAYERS), can be obtained by noting the direction of your SHADOW 
	near the time of SUNSET.  The direction in which your shadow goes
	is usually a little north of east DURING WINTER.  This is the 
	direction in which salat can be performed, as an approximation.  
	This direction of the shadow changes during the different months 
	of the year but is a good approximation when there is no magnetic 
	compass to determine the exact direction.  During summer, the 
	shadow goes south of east and hence we would have to turn further
	north from the shadow, ie. further to the left of the evening shadow.
	For locations in the West of America the direction is even further 
	North from the shadow, ie. even further to the left of the shadow.
 
 ****************************************************************************
 
	Copyright  Dr.M.N.Durrani, 1987 to 1997
	Permission to copy for free distribution is granted to all,
	please do give credit and reference. Thanks.
 
	For further information, please feel free to contact:
 
	Mail:      Dr.Mohib.N.Durrani
		   Islamic Amateur Astronomers Association
		   (Research Division)
		   601 West 113 Street, Suite 11-K
		   Columbia University
		   NEW YORK, N.Y. 10025
		   United States of America
  
	Email to:  mnd0@columbia.edu 
 
 
 ***************************** End of Document ******************************

Bismillah hir-Rahman nir-Rahim

(In the name of ALLAH, THE MOST BENEFICENT, THE MOST MERCIFUL) THE MUSLIM STUDENTS' ASSOCIATION (MSA) of COLUMBIA UNIVERSITY 102 Earl Hall, Columbia University, NEW YORK, N.Y. 10027 GUIDE TO SIGHTING THE HILAL (CRESCENT MOON)