A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Gary LaPook
Date: 2015 Nov 22, 15:15 -0800
Remember, HO 249 was developed for use by flight navigators where speed of obtaining a fix is of utmost importance. Flight navigators precompute all of their sights so refer to HO 249 volume 1 first to select which stars they will plan to shoot. Since flight navigators use metods that allow the use of just one AP for all the shots of stars and allow for movement of the plane and of the stars during the shooting period he can put the fix on his chart within 5 minutes of the finsh of the last shot. If he is shooting the sun or the moon (which is what the other two volumes are really for. If shooting at night there is no reason to use the moon or planets, just use the stars in Volume 1) for a daylight LOP or daylight fix he does the same kind of computation that you do with HO 229 but he does all the computations prior to picking up his sextant.