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+.help h2e Jun99 "Slalib Package"
+.nf
+
+      SUBROUTINE slH2E (AZ, EL, PHI, HA, DEC)
+
+     - - - - -
+      D E 2 H
+     - - - - -
+
+  Horizon to equatorial coordinates:  Az,El to HA,Dec
+
+  (single precision)
+
+  Given:
+     AZ      r     azimuth
+     EL      r     elevation
+     PHI     r     observatory latitude
+
+  Returned:
+     HA      r     hour angle
+     DEC     r     declination
+
+  Notes:
+
+  1)  All the arguments are angles in radians.
+
+  2)  The sign convention for azimuth is north zero, east +pi/2.
+
+  3)  HA is returned in the range +/-pi.  Declination is returned
+      in the range +/-pi/2.
+
+  4)  The latitude is (in principle) geodetic.  In critical
+      applications, corrections for polar motion should be applied.
+
+  5)  In some applications it will be important to specify the
+      correct type of elevation in order to produce the required
+      type of HA,Dec.  In particular, it may be important to
+      distinguish between the elevation as affected by refraction,
+      which will yield the "observed" HA,Dec, and the elevation
+      in vacuo, which will yield the "topocentric" HA,Dec.  If the
+      effects of diurnal aberration can be neglected, the
+      topocentric HA,Dec may be used as an approximation to the
+      "apparent" HA,Dec.
+
+  6)  No range checking of arguments is done.
+
+  7)  In applications which involve many such calculations, rather
+      than calling the present routine it will be more efficient to
+      use inline code, having previously computed fixed terms such
+      as sine and cosine of latitude.
+
+  P.T.Wallace   Starlink   21 February 1996
+
+  Copyright (C) 1996 Rutherford Appleton Laboratory
+  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
+
+.fi
+.endhelp