A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Tony Oz
Date: 2018 Aug 17, 04:31 -0700
You mentioned the collimation error - which MUST be there in any "bris".
But is it relevant?
As I understand the calibration process, it accounts for each and every condition: the HoE, the refraction - AND the collimation error(s). Since the mirrors are fixed - whatever I measured through them - will repeat forever. It would matter if I derived the HC from the angle I intended to achieve when glueing the mirrors (expecting it to be some certain pre-selected value). But actually it is the other way around! We do not even know the angles within our "bris" exactly, we know that if a body was that much high - its' Nth reflection would touch the horizon. That value is obtained (as you perfectly understand) by calculation alone - disregarding the details of "bris" construction.