API field
Air-mass cap
Highest air mass fed to the correction; empty = 10 with Kasten–Young, none otherwise
Unit –
What it is
An upper limit on the air mass fed to the Lee and Panchula correction. At very low sun the air mass grows large and the correction formula leaves its fitted range. Empty means no cap with the Kasten 1966 air mass and a cap of 10 with the Kasten–Young air mass.
Typical values and how to get it
Empty, or 10.
API
spectral.am_max