Celestial Theodolite

The celestial theodolite (CT) is a proposed method for verifying Earth's curvature by recording the time that a star is occulted by a terrestrial object (typically a mountain peak) of known distance and known relative elevation. The method was created by Mike Heffron. Flerfs claim that the CT method produces data that is consistent with a flat Earth and not a globe. Flerfs Space Audits and Shane St. Pierre are notable proponents of CT.

Method

The CT method ultimately compares the "predicted" elevation angle of the star in Stellarium with the calculated elevation angle of the mountain peak assuming a flat Earth. The only data that is actually collected is the time of occlusion . This is because if flerfs used an actual theodolite to measure the elevation angle of the mountain peak, it would confirm the globe.

As described by roohif:

Basically they record the time that a star is occluded behind a mountain, perform some fuckery in Stellarium to get an angle, then they compare that angle to the raw, flat Earth trig.

Calculating the FE elevation angle

Once a mountain peak and observer location is selected, the haversine formula (which uses spherical geometry) is used to compute the distance between the the two locations. The elevation angle assuming flat Earth can then be calculated using:

$\theta =\arctan \frac{\mathrm{\Delta }h}{d}$

Where Δh is the difference in elevation between the observer and peak, and d is the horizontal distance between the observer and mountain. It's important to note that in this step, the horizontal distance is assumed to be flat despite having obtained this value under the assumption that earth is spherical.

List of globe earth assumptions

The CT method as proposed by flerfs uses several globe earth assumptions and calculations, including:

• The distance between the observer and the mountain (see: haversine formula)
• The predicted altitude angle of the star
• The amount of astronomical refraction
• Stellarium being accurate whatsoever, given it uses globe earth to make predictions

This list is a confirmation of the First Law of Flerf.