NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David C
Date: 2019 Jun 20, 02:11 -0700
Today I was sitting in the midday sun supervising a granddaugter in her sand pit. I was thinking about the winter solstice which is just two days away and decided to measure my latitude.
The shadow is at its shortest length.
height 635mm
length 1365mm
20th June 2019 0021 UT.
My intention was to use the Cambridge Four-Figure Mathematical Tables (1946 edition) but I cheated and used my fx-82AU calculator.
Sun's altitude arc tan( 9635/1365) = 24.95°
Now some more cheating - rather than look at the Air Almanac I used a phone app to determine that the sun's dec is 23.4°.
Thus lat = 90 - 23.4 - 24.95
= 41.65°
= 41° 39'
My gps lat was 41° 14' so that an error of 25'. I am quite happy with that given that it was a spur of the moment decision while supervising a 3 year old. Note that I did not check that the pipe was vertical and my measurments were rough and ready. Also the pipe had a diameter of several inches which is why it stood up by itself.
My inspiration to make this measurement came from a TV program about the Long Range Desert Group that I watched a few days ago. IIRC their navigator was someone by the name of Sadler. A sun compass was shown but given that it was in pristine condition I suspect that it was filmed in a museum. I wondered if he was the Sadler of Nautical Almanac fame but a quick google indicated that he was not.
It is good that the sun will soon be returning to the southern hemisphere but unfortunately the weather is about ninety degrees out of phase with the sun and so the worst weather of the year is still to come.
