FUNCTION clv,ldis,lam,mu ; ; Calculation of solar disk intensity at a given distance from the limb ; - or, alternatively at a given heliocentric distance MU - ; according to "Allen's Astrophysical Quantities, 4th ed., 2000, p. 355. ; ; INPUTS: LDIS = distance from the limb in arcsec (disk center = 960) ; ldis can be an array. ; If LDIS < 0 then MU must contain input value(s) ; LAM = wavelength in A ; OUTPUTS: Intensity normalized to disk center (I(960) = 1) ; MU = cos(theta) - heliocentric angle (optional), ; in case of LDIS < 0 used as an input. ; EXAMPLE: i=clv(20,4500,mu) ; ; 1 October 2003, Michal ; on_error,1 if (max(ldis) lt 0 and n_params() lt 3) or (n_params() lt 2) then $ message,'Usage: i=CLV(limb-dist,lambda [,mu]) or i=CLV(-1,lambda,mu)' wav=[3500,3700,3800,4000,4500,5000,5500,6000,8000,10000,15000] u1 =[0.98,1.03,0.92,0.91,0.99,0.97,0.93,0.88,0.73,0.64,0.57] v1= [0.10,0.16,0.05,0.05,0.17,0.22,0.23,0.23,0.22,0.20,0.21] mi=min(abs(wav-lam),pos) ;looking for table wavelength u2=u1(pos) ;finding coefficients v2=v1(pos) if max(ldis) ge 0 then mu=sqrt(1-(1-ldis/960.)^2) ii=1-u2+v2+u2*mu-v2*mu^2 RETURN, ii END