Shadow Contacts and Circumstances, Total Solar Eclipse of 1999 August 11 Table 2. Ephemeris Longitude is the terrestrial dynamical longitude assuming a uniformly rotating Earth.
Longitude is measured positive to the East.
Since T is not known in advance, the value used in the predictions is an extrapolation based on pre-1997 measurements. Nevertheless, the actual value is expected to fall within 0.3 seconds of the estimated T used here.