NavList:

Sam,

It looks as if you are working a 249 reduction in reverse.  This would be a way to recover time if the chronometer stopped and position is known. There would be an azimuth and intercept from an assumed position to the known position so that the LOP passes through the known position. Better to use a reduction method that uses the known position as the assumed position such as the classic trig log, Ageton, or haversine Doniol. 

Greg Rudzinski

From: Samuel L
Date: 2015 Jun 1, 04:12 -0700

I've taken several morning Sun sights without recording the time (except for later general reference), reduced to Ho and then compared the Ho to the closest figure Hc figure in HO 249 given a whole number Declination and Latitude. Next, taking the LHA wherein the Hc lies and adding AP Longitude and subtracting 360 a GHA figure is arrived at. The GHA figure is converted in Table 3 Arc to Time with the result very close, about 1 minute) to actual UTC of the shot. It's a pretty remarkable process.

The question I have is this- when will the technique mentioned above yield grossly inaccurate results- off by over 5 minutes? When the EoT is much different than it is at this date?

Thanks,

Sam L.