The spacing of the sky tracks of the ALFA beams in the
19 deg rotated configuration is about 2.1 arcminutes. For a HPBW
of 3.5 arcminutes, we would ideally space the beams closer than 2.1
arcmin to get complete resolution.
- For the second pass, we want the beams to produce drift scan tracks
that are halfway between the ones of the first pass, producing a final
spacing of 1.05 arcminutes.
- Since Beam 0 is more sensitive (higher gain) than the
outer beams, we center it for the 2nd pass 7.3 arcmin from its 1st pass