A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David C
Date: 2020 Jun 30, 13:43 -0700
For me the quickest most accurate way to do a time sight is with a trig calculator (Casio fx 300es is a good one) and the formula :
Arc Cos } (sin lat sin dec +/- sin Ho) / (cos lat cos dec) = (t) LHA
I agree that if the aim is to reduce a sight as quickly and easily as possible then a calculator is best. The formula for h is easy to remember and if I make the effort I could probably remember the formula for t. On my fx-82AU the memories are saved when the calculator is turned off. I use the following conventions:
The formulas are not saved on power down but with the data saved in memory it is quick and easy to enter the formula. If working a series of sights I have to be aware that the calculater will turn off off after a few minutes of non-use.
If however I am working a sight because of an interest in CN history then the calculator is of no use. I have a choice of dozens, if not hundreds,of methods. Yesterday I was reading a twenty+ year old forum in which navigators discussed "Nories or Burtons". Nories must have been the preferred tables in south lats because until recently every second hand bookshop had one or two copies of Norie. I have never seen a copy of Burtons so maybe it is time for an online search.