
 Sight Reduction Worksheet for HO-211 Ageton's Tables

            A & B LOG'S            
            ===========            
     A(t) =
 + B(Dec) =
 ----------------------
     A(R) =
  - B(Hc) =                          ANGLE'S DEG 
 ----------------------              ===========
     A(Z) =             >        Z =



   A(Dec) =
   - B(R) =
-----------------------       Give K the same name as Dec
     A(K) =             >        K =            
                             +-Lat =
                             -----------------------
 B(K~Lat) =             <   K~Lat* =
   + B(R) =
-----------------------
    A(Hc) =             >       Hc =

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 Give K the same name as Dec

 * Add K and Lat if they are of contrary name. Otherwise subtract
    the smaller from the greater quantity.

 If the meridian angle, t, is greater than 90 deg, take K from the bottom
   of the table.  (bottom is 90 to 180 deg area)

 Always take Z from the bottom of the table, except when K is same name
   and greater than Lat, in which case take Z from the top of the table.

 Apply the following rules to find the true azimuth, ZN:
   Zn = Z       IF LAT > 0(N) AND T < 0(E)
   Zn = 180 - Z IF LAT < 0(S) AND T < 0(E)
   Zn = 180 + Z IF LAT < 0(S) AND T > 0(W)
   Zn = 360 - Z IF LAT > 0(N) AND T > 0(W)

 Hc is below horizon if K~Lat > 90 degree.

 -------------------------------------------------------

 t, Dec, and Lat are entered rounded to nearest 0.5 minutes, if original HO-211 table.
 Use DR Lo and DR Lat, assumed position not needed.

 -------------------------------------------------------

 If K is between 82 and 98 degrees, then interpolate from A(R) to B(R).

   A         B
 A(LOW)    B(LOW)    LOG'S A & B FOR LOWER TABLE ANGLE 
 A(R)      B(R)      LOG'S FOR EXACT ANGLE
 A(HIGH)   B(HIGH)   LOG'S A & B FOR HIGHER TABLE ANGLE

 B(R) = B(HIGH) + ( A(R)-A(HIGH) ) / ( A(LOW)-A(HIGH) ) * ( B(LOW)-B(HIGH) )

 Near 90 deg B(R) needs 0.1 minute resolution.

 ---------------------------------------------------------------------------

 Henning Umland,  http://home.t-online.de/home/h.umland/
 You can also print a Ageton worksheet contained in: tables-AGETON-HO211.zip
   or compact.zip

 ---------------------------------------------------------------------------

Sight Reduction using the Adgeton method (inverted) - (ref page C2)

     sin R = sin t * cos Dec       (R is less than 90 degrees )
     sin K = sin Dec / cos R       (note 1)
     sin Hc = cos R * cos (K~Lat)  (e is less than 90 degrees )  
     sin Z = sin R / cos Hc        (note 2)                      

(note 1) If t is greater than 90 degrees then
         K is greater than 90 degrees.
(note 2) If Lat is greater than K then Z is greater
         than 90 degrees.
         If K has same name as L, and K > L, then Z < 90 degrees,
         otherwise Z > 90 degrees. 
(K~Lat)  If Contrary name, then add them.
         If Same name, then subtract them. 

 from http://www.angelfire.com/nt/navtrig/E5.html

