NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: True Distance vs. Observed Distance
From: Bill B
Date: 2012 Sep 17, 18:53 -0400
From: Bill B
Date: 2012 Sep 17, 18:53 -0400
On 9/17/2012 3:09 PM, Marcel Tschudin wrote: > Looking at Bill's Excel spread sheet "A Nav Ang Sep Refract Mas" shows > that he did indeed use this formula. I was however not able to calculate > with it the star distance of Greg's observation. Just finished tests with the .xlsx version posted. Spreadsheets attached. I don't think I have enough information to use with the spread sheet for both evenings. Using the location, elevation, temp and pressure from Greg's 9/15/12 3:38 PM posting and the cel nav data from the "f2-Picsture-70.png" image attached to his 9/16/12 12:37 AM posting I obtain the following: Deneb/Vega 23d 50!4 Alioth/Aikaid 10d 27!6 The Deneb/Vega exactly matches Greg's earlier Tamaya observation, but since I do not know the time of the prior evenings observation, it is apples to oranges. When developing the spreadsheet in 2005, I added elevation and perhaps a few other things Alex did not feel were significant like calculating refraction from a star's Hc, rather than working backwards from the almanac tables (if I recall correctly). When we compared notes were were usually spot on, and seldom more that 0!1 apart. Given Alex's expertise (with the possible exception of abnormal refraction ;-), I tend to trust our numbers. Bill B
