Index: /trunk/doc/pslib/psLibSDRS_Astrom.tex
===================================================================
--- /trunk/doc/pslib/psLibSDRS_Astrom.tex	(revision 1598)
+++ /trunk/doc/pslib/psLibSDRS_Astrom.tex	(revision 1599)
@@ -123,5 +123,5 @@
     psPlaneTransform *cellToFPA;        ///< Transformations from cell coordinates to FPA coordinates
     psPlaneTransform *toTP;             ///< Quick and Dirty transformations from cell coordinates to sky
-    struct psChip  *parentChip;         ///< chip which contains this cell
+    struct psChip *parentChip;          ///< chip which contains this cell
 } psCell;
 \end{verbatim}
@@ -197,5 +197,4 @@
     const double zd;                    ///< Zenith distance
     const double az;                    ///< Azimuth
-    const double lst;                   ///< Local Sidereal Time
     const psTime *time;                 ///< Time of observation
     const float rotAngle;               ///< Rotator position angle
@@ -207,4 +206,5 @@
     const psObservatory *observatory;   ///< Observatory data
     /* Derived quantities */
+    const psTime lst;                   ///< Local Sidereal Time
     const float posAngle;               ///< Position angle
     const float parallactic;            ///< Parallactic angle
@@ -239,5 +239,5 @@
 The constructor for \code{psExposure} shall be:
 \begin{verbatim}
-psExposure *psExposureAlloc(double ra, double dec, double ha, double zd, double az, double lst,
+psExposure *psExposureAlloc(double ra, double dec, double ha, double zd, double az,
                             const psTime *time, float rotAngle, float temp, float pressure, float humidity,
                             float exptime, float wavelength, const psObservatory *observatory);
@@ -567,7 +567,8 @@
 
 \begin{verbatim}
-float psGetAirmass(const psSphere *coord, double siderealTime, float height);
-\end{verbatim}
-which returns the airmass for a given position and sidereal time.
+float psGetAirmass(const psSphere *coord, psTime *lst, float height);
+\end{verbatim}
+which returns the airmass for a given position and local sidereal time
+(\code{lst}).
 
 \begin{verbatim}
@@ -587,4 +588,4 @@
 double psGetParallaxFactor(const psExposure *exp)
 \end{verbatim}
-Calculate the parallax factor for the given exposure \tbd{why do we
-  need this?}.
+Calculate the parallax factor for the given exposure.  \tbd{Why do we
+need this?}.