Variable  Symbol  Value 
R.A. 1  a_{1}  290°.29484 
R.A. 2  a_{2}  293°.03953 
Change in R.A.  Da  2°.74467 
Change in Dec.  Dd  2°.94401 
Average Declination  d_{av}  45°.04611 
Orbit Inclination  i  67°.13 
Now that we have determined the semimajor axis and inclination of the satellite's orbit, we can use this knowledge to determine the orbit's right ascension of ascending node (RAAN). This value denotes the point at which the satellite's orbit plane crosses the Earth's equatorial plane as the satellite crosses (ascends) from the southern to the northern hemisphere. First, we need the average right ascension of the satellite streak: a_{av} = [ a_{1} + a_{2} ] / 2 a_{av} = 291°.66717 Next, we can calculate the RAAN. Be very careful when considering the conditions or the determined orbit can have the wrong plane! If Da>0 and Dd>0 then a_{W} = a_{av}  sin^{1} [ tand_{av} / tan(i) ] If Da>0 and Dd<0 then a_{W} = a_{av}  180° + sin^{1} [ tand_{av} / tan(i) ] If Da<0 and Dd>0 then a_{W} = a_{av} + sin^{1} [ tand_{av} / tan(i) ] If Da<0 and Dd<0 then a_{W} = a_{av} + 180°  sin^{1} [ tand_{av} / tan(i) ] Da > 0 and Dd < 0 a_{W} = 136°.66 RAAN is normally expressed in degrees, not hours. The RAAN indicates the right ascension of the node created by the intersection of the equatorial plane of the Earth and the satellite's orbit as the satellite ascends (moves from south to north).


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Step 6: Right Ascension of Ascending Node Was Last Modified On December 31, 2013 