.nf
/AIRMASS airmassStart [TO] airmassEnd [BY] airmassStep

range of airmass for TIP.

Real      :: airmassStart      ! 
Real      :: airmassEnd        ! 
Real      :: airmassStep       ! 

NOTE 1: elevation = ASIN(1/airmass)

NOTE 2: for slew-tips, TIP /SLEW:
        airmassStep has no effect
        airmassStart > airmassEnd is allowed; this implies:
        elevation (at start) < elevation (at end), i.e., 
        TIP from low to high elevation.

        (for "traditional" TIP with /SLEW no, airmassStart < airmassEnd,
        i.e., they go from high to low elevation.)

.fi

