A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2018 Nov 2, 12:14 -0700
In all of my professional metrology work, we typically expected the measuring instrument to be certified as calibrated to 10 times smaller than the value we were trying to measure.
For example, if we wanted to publish data good to 0.1 arcminutes, we would require that the instrument be capable of measurement to 1/10 of that or 0.01 arcminutes (0.6 arcseconds).
If we are to believe your data point of 0.1 arcseconds of latitude, then the instrument should be good to sbout 0.01 arc seconds.
Were period transits capable of such measurement?