About azimuth angle definition for asc_desc2horz_vert.py

[esrivas17]

Dear Mintpy developers,

I have been trying to understand what happens under the hood of the aforementioned script, specially with the azimuth angle.

in #857, it is said that azimuth angles should be around 102.6 deg for ascending orbit and -102.6 for descending orbit.
And I can understand this as this value is about heading + 90 deg. (measured from the north and positve counterclockwise as Mintpy standards).

However, it is still not clear why in ISCE/Mintpy, the azimuth angles returned are about -256, -259 for ascending orbits. This is also shown in #857.
And it is also the case for my data (ascending track 59 - Sentinel)

Later in the calculation of horizontal and vertical component, in this function
we subtract 90 degrees to the azimuth, why is this needed?

Hoping, this is clear enough to be understood and get an answer from you guys,
Thank you