      REAL FUNCTION RLWPLK(WV,TT)
      IMPLICIT NONE
C
C**********************************************************************
C
C   NAME- RLWPLK
C
C   LANGUAGE- FORTRAN     TYPE- FUNCTION
C
C   VERSION- 1.0    DATE- 02/26/92   PROGRAMMER- LEAH WILSON (H-STX)
C   VERSION- 3.0    DATE- 06/19/97   PROGRAMMER- LEAH WILSON (H-STX)
C   VERSION- 4.0    DATE- 06/05/02   PROGRAMMER- RICH KELLEY (CSC)
C
C   FUNCTION-*$ED30MG* THIS PROGRAM COMPUTES PLANCK RADIANCE AT
C        A GIVEN WAVENUMBER FOR PHYSICAL RETRIEVAL ROUTINES.
C   VERSION- 3.0 MODIFICATIONS FOR INCLUSION INTO ATOVS.
C   VERSION- 4.0 UPDATED VALUES FOR PLANCK CONSTANTS C1 AND C2 BASED ON
C                FPDT PR47 DATED 8/13/2001.
C
C   PARAMETERS-
C      VARIABLE                TYPE I/O FUNCTION
C      --------                ---- --- --------
C        WV                    REAL I   WAVENUMBER
C        TT                    REAL I   TEMPERATURE VALUE (KELVIN)
C
C*********************************************************************
      REAL C1, C2, WV, TT
      C1=1.1910427E-05
      C2=1.4387752
      RLWPLK=C1*(WV**3.)/(EXP(C2*WV/TT)-1.)*.001
      RETURN
      END
