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Question about Pub 249 combined Star and Planet sight reduction
From: Rod Deyo
Date: 2000 Nov 16, 8:49 PM
From: Rod Deyo
Date: 2000 Nov 16, 8:49 PM
I have the following navigation problem. Suppose I have taken sights for two planets and three stars well chosen from Pub. 249 Vol 1. Each of the two planet's GHA and declination are found from the Nautical Almanac and Hc found from the corresponding AP and LHA using Pub. 249 Vols 2 or 3 (or perhaps Pub 229). LOPs are then plotted for each planet. Next, the three star Hc obtained directly from Pub. 249 Vol 1 and LOPs are plotted (again, advanced, if needed, to the common time). But I should now correct the Pub. 249 star fix (or, equivalently, the APs or LOPS) using Vol 1 Table 5 corrections for procession and nutation for the appropriate year and LHA. Ntoe that I do not need to do this for the planets since that information has already been incorporated into the Almanac data. Suppose I choose to correct the star fix. This gives me a single fix from the three star sights, but no easy way to do least square fit or other unbiased average simultaneously against the planet LOPs as well. My question - is there a way to properly weigh the single, corrected star fix against the individual planet LOPs? Alternatively, I could have gone ahead and adjusted each individual star AP (or LOP) for the procession and nutation correction and then found the overall least square fit among all five star and planet LOPs to determine the final fix (equivalent to using tha Almanac, GHA Aries, and Pub. 229 for each star). But is there an easier way, more in the spirit of Pub. 249? Thanks! Rod Deyo
