;	(23-jan-91)
FUNCTION SUN_B0,DAY79
;+
; NAME:
;	SUN_B0
;	
; PURPOSE:
;	Calculate solar reference angle B0 for date specified by D79
;
; CALLING SEQUENCE:
;	B0 = SUN_B0(DAY79)
;
; INPUT:
;	DAY79 = Decimal days since 1 January, 1979
;
; OUTPUT:
;	B0 = Heliographic latitude of the central point of the
;
; MODIFICATION HISTORY:
;	Version 1.0 - Jan, 1991, Written, G. L. Slater, LPARL
;
; NOTES:
;	See PB0R.PRO for more information on this calculation.
;-
dont_use_this, 'GET_RB0P', 'SUN_B0', 'Sample calling sequence: r = get_rb0p(times, /b0)'

  a0 = 0.01720197d*(day79-3.5)
  return, asin(0.126199d*cos(a0+0.033685d*sin(a0)-4.23986d))
  end