30.0” South and 30.0” West.
To the nearest 30 seconds N and W with a sextant? That’s incredibly precise — a second of arc on the earth’s surface is about 100 feet.
Was he really precise to a tenth of a second? Why are both measurements to 30.0 seconds on the dot?
I once actually knew how to do celestial navigation, but have no recollection of how precise the sextants were.
According to the Wikipedia writeup on sextants, a skilled navigator can determine position to within about a quarter mile.
https://en.wikipedia.org/wiki/Sextant