SUBROUTINE CPVBQ1 (BX,BY,BZ,SWD,SWV,POT)
C     This subroutine finds the crosstail potential from the Reiff
C     formula for Crooker Compression vBQ1, REIFF and LUHMAN, 1986.
 
      IF ((BX .EQ. -32767.) .OR. (BY .EQ. -32767.) .OR.
     +    (BZ .EQ. -32767.) .OR. (SWD .EQ. -32767.) .OR.
     +    (SWV .EQ. -32767.)) THEN
           POT = -32767.
           RETURN
      ENDIF
 
      B=SQRT(BX**2+BY**2+BZ**2)
      BM=AMIN1(B,7.)
      BT=SQRT(BY**2+BZ**2)
      BE=SQRT(2.*0.002098*SWD*SWV**2+BT**2)
      BS=2.*SQRT(BT*BE)
      BS=AMIN1(BS,BE)
      X=0.
      C8=BS/BE
      C9=BZ/BT
      IF (C8 .GE. C9) X=SWV*BM*C8*(C8-C9)/SQRT(1.+C8**2-2.*C8*C9)
      POT=25.+0.062*X
      RETURN
      END