Transit Duration and Azimuth

[abdeldjalil-fellah]

Latitude: 36.0
Date: 25/09/2018
Sun Apparent Diameter: 0.53163

When the West Edge of the Sun Disk crosses the Transit Line (Az = 180.0):
the expected Sun Azimuth is: 180.0 - 0.53163/2 = 179.734185 but Stellarium shows : 179.556

When the East Edge of the Sun Disk crosses the Transit Line (Az = 180.0):
the expected Sun Azimuth is: 180.0 + 0.53163/2 = 180.265815 but Stellarium shows : 180.4472

[gzotti]

You forgot that azimuth lines converge towards the zenith.

Latitude 36, noon altitude 53°.
180.0+0.53163/2/cos(53°)=180.44...