This is the Figaro source code that seems to be relevant.
SUBROUTINE VCHLCON(ARRAY,NX,VEL,VELLG,VACLG)
C
C This routine does the calculation of the new wavelength scale,
C with conversion for one or both of air to vacuum and correction
C for recession velocity VEL.
C ARRAY is the (data mapped) output array, which also holds the
C input data when entering this routine.
C NX is the size of the X structure (wavelength array).
C VEL is the recession velocity in Km/s which is to be corrected
C for (negative if approach velocity).
C VELLG = .TRUE. if velocity correction is to be done
C VACLG = .TRUE. if air to vacuum correction is to be done
C
DOUBLE PRECISION ARRAY(NX)
LOGICAL VELLG,VACLG
DOUBLE PRECISION C,WAVM,SUM,REFIND
C
C = 2.99792E+5
C
IF(VELLG)VFACT=SQRT((1.-VEL/C)/(1.+VEL/C))
C
DO I =1,NX
IF(.NOT.VACLG)GO TO 1 ! Do vacuum conversion here
WAVM=1./(ARRAY(I)*1.E-4)**2 ! 1/(wavelength in
microns)**2
SUM = 64.328 + 29498.1/(146.-WAVM) + 255.4/(41.-WAVM)
REFIND = SUM*1.E-6 + 1. ! Refractive index
ARRAY(I) = ARRAY(I)*REFIND
C
1 IF(.NOT.VELLG)GO TO 2 ! Do velocity conversion here
ARRAY(I) = ARRAY(I)*VFACT
C
2 CONTINUE
END DO
RETURN
END
On Jan 4, 2008, at 11:52 AM, Sara Gettel wrote:
> Hi all,
> Could someone tell me which atmospheric standard VACHEL uses to for
> air-to-vacuum corrections?
>
> Thanks,
> Sara Gettel
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