I recently obtained my celestial navigation certification
but there was an exam question that still puzzles me.
The question was looking for a three point fix using Venus, Vega and Polaris. We were asked to give the Zn and 'a' (intercept) for each. I had no problem with Venus or Vega but where I had issues was with Polaris.
I get that the LHA, A. Lat allows you to enter the Polaris table using the corresponding column for the Ha and then using Ao, A1, A2, -1 degree to get your Latitude.
At the bottom of the Polaris table you can determine the Zn, which varies around 359 degrees plus a few minutes. So that gives me my Zn, but what about the intercept?
Typically you use the Declination, sight reduction tables to determine Hc and then the difference between the Hc and the Ho gives you your intercept. No declination is given for Polaris but I believe that it is 90 degrees. Sight reduction tables only deal with Delinations up to 29 degrees.
So, what I have come up with is, my intercept is Zero since Ao, A1 etc. are used to place me on the line (circle) of position based on my sextant
altitude reading of Polaris. In other words, there is no intercept because I am already on the line of position.
Can anyone confirm that I am right?