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+      SUBROUTINE sla_SUPGAL (DSL, DSB, DL, DB)
+*+
+*     - - - - - - -
+*      S U P G A L
+*     - - - - - - -
+*
+*  Transformation from de Vaucouleurs supergalactic coordinates
+*  to IAU 1958 galactic coordinates (double precision)
+*
+*  Given:
+*     DSL,DSB     dp       supergalactic longitude and latitude
+*
+*  Returned:
+*     DL,DB       dp       galactic longitude and latitude L2,B2
+*
+*  (all arguments are radians)
+*
+*  Called:
+*     sla_DCS2C, sla_DIMXV, sla_DCC2S, sla_DRANRM, sla_DRANGE
+*
+*  References:
+*
+*     de Vaucouleurs, de Vaucouleurs, & Corwin, Second Reference
+*     Catalogue of Bright Galaxies, U. Texas, page 8.
+*
+*     Systems & Applied Sciences Corp., Documentation for the
+*     machine-readable version of the above catalogue,
+*     Contract NAS 5-26490.
+*
+*    (These two references give different values for the galactic
+*     longitude of the supergalactic origin.  Both are wrong;  the
+*     correct value is L2=137.37.)
+*
+*  P.T.Wallace   Starlink   March 1986
+*
+*  Copyright (C) 1995 Rutherford Appleton Laboratory
+*-
+
+      IMPLICIT NONE
+
+      DOUBLE PRECISION DSL,DSB,DL,DB
+
+      DOUBLE PRECISION sla_DRANRM,sla_DRANGE
+
+      DOUBLE PRECISION V1(3),V2(3)
+
+*
+*  System of supergalactic coordinates:
+*
+*    SGL   SGB        L2     B2      (deg)
+*     -    +90      47.37  +6.32
+*     0     0         -      0
+*
+*  Galactic to supergalactic rotation matrix:
+*
+      DOUBLE PRECISION RMAT(3,3)
+      DATA RMAT(1,1),RMAT(1,2),RMAT(1,3),
+     :     RMAT(2,1),RMAT(2,2),RMAT(2,3),
+     :     RMAT(3,1),RMAT(3,2),RMAT(3,3)/
+     : -0.735742574804D0,+0.677261296414D0,+0.000000000000D0,
+     : -0.074553778365D0,-0.080991471307D0,+0.993922590400D0,
+     : +0.673145302109D0,+0.731271165817D0,+0.110081262225D0/
+
+
+
+*  Spherical to Cartesian
+      CALL sla_DCS2C(DSL,DSB,V1)
+
+*  Supergalactic to galactic
+      CALL sla_DIMXV(RMAT,V1,V2)
+
+*  Cartesian to spherical
+      CALL sla_DCC2S(V2,DL,DB)
+
+*  Express in conventional ranges
+      DL=sla_DRANRM(DL)
+      DB=sla_DRANGE(DB)
+
+      END