alpha_prime calculated without usage

[KonstantinTr]

Two functions (namely solar_position_numpy and solar_position_loop) of spa module calculate alpha_prime without any usage.

Should it be passed as a argument later in the code? I had checked argument names for all following calls and didn't find topocentric_sun_right_ascension among arg names.

[wholmgren]

I don't think it's needed here, but can you check the reference? We should skip the calculation if it's not needed.

[KonstantinTr]

I close this issue as far as it was solved with already merged PR #383