NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2014 Dec 30, 20:07 -0800
Sam,
The group of selected stars changes so that altitudes and azimuths are optimal for aircraft CN. Your Vega fell out of favor at LHA Aries 15° but was still selected at LHA Aries 14°. So you need to adjust your assumed position so that you have a LHA of 14°. This means shifting the assumed longitude to 76° 52.1 W for a GHA of 90° 52.1' for Aries. Of course the intercept will be long but still good. I'm getting an intercept of 45' away with an azimuth of 304° by USNO data using Lat. 39°N Lon. 76° 52.1' W. Don't forget to correct for precession and nutation if using the Hc from 249 volume 1 for calculating an intercept.
Greg Rudzinski
From: Samuel L
Date: 2014 Dec 30, 17:16 -0800I'm not certain if I'm using HO-249 Vol 1 correctly for sight reduction.
For instance- tonight, 12/30/2014 I took a site of Vega. Here are the particulars;
GMT- 23:26:11
Ho- 19d 26.1min
GHA- 90d 53min
AP Longitude- W075d
LHA- 15d
When reviewing HO 249 Vol. 1 for N39d and LHA 15d the only close LHA reference to Vega is an LHA of 14d.
Is the answer- "you should've gotten out there earlier?"
Sam L
