05-08-2019, 05:59 AM
Hello all!
Great forum here. I've been browsing and learning for a week; as esoteric as it might be these days, it's nice to have a dedicated place for this subject, for people like me that are just learning.
I have a question I wanted to run by you. I've done a few manual sight reductions using the tables and a Davis Mark 3 with a bowl of water for an artificial horizon, and been getting LOPs with accuracy within a few miles which I feel is acceptable for a beginner with such a hokey setup ;). But I've also been using an online sight reduction calculator just to make the practice process faster (yes it's cheating, but who doesn't just want to play with a new toy for a bit?) I've been using this calculator:
https://www.celnav.de/sightred.htm
Along with the USNO almanac data. Seems to work well; again, LOPs within a few miles. But I'm curious: using the tables, it seems (at least with the tables and forms I've been using) necessary to adjust your initial Assumed Position longitude during the conversion to LHA. This "adjusted" AP longitude is then used in the LOP plotting process.
So: is it necessary to also adjust the longitude of the Assumed Position when using that online calculator? I'm guessing not, because, well, plotting the LOP using the calculated intercept from the original AP seems to work well, and the calculator doesn't supply a modified AP longitude. I'm *guessing* that since this is a calculator, it's solving the appropriate formulae using the actual AP, without any modification being driven by the tables.
Sanity check? Am I right to plot the LOP directly from my original assumed position when using this online calculator?
Thanks!
Great forum here. I've been browsing and learning for a week; as esoteric as it might be these days, it's nice to have a dedicated place for this subject, for people like me that are just learning.
I have a question I wanted to run by you. I've done a few manual sight reductions using the tables and a Davis Mark 3 with a bowl of water for an artificial horizon, and been getting LOPs with accuracy within a few miles which I feel is acceptable for a beginner with such a hokey setup ;). But I've also been using an online sight reduction calculator just to make the practice process faster (yes it's cheating, but who doesn't just want to play with a new toy for a bit?) I've been using this calculator:
https://www.celnav.de/sightred.htm
Along with the USNO almanac data. Seems to work well; again, LOPs within a few miles. But I'm curious: using the tables, it seems (at least with the tables and forms I've been using) necessary to adjust your initial Assumed Position longitude during the conversion to LHA. This "adjusted" AP longitude is then used in the LOP plotting process.
So: is it necessary to also adjust the longitude of the Assumed Position when using that online calculator? I'm guessing not, because, well, plotting the LOP using the calculated intercept from the original AP seems to work well, and the calculator doesn't supply a modified AP longitude. I'm *guessing* that since this is a calculator, it's solving the appropriate formulae using the actual AP, without any modification being driven by the tables.
Sanity check? Am I right to plot the LOP directly from my original assumed position when using this online calculator?
Thanks!