Spectra Precision Survey Pro CE v3.6 User Manual - Manual (Page 256)

Survey Menu
R-99
Note: Typically Left Edge of Center is selected when performing a sun
shot in the northern hemisphere and Center is selected for star shots.
&RUUHFWLRQV : displays which corrections are
currently selected with an N for no, or a Y for yes.
When tapped, the Corrections dialog box opens
where the following corrections are configured.
• ;
Non-linear Declination Correction :
applies a correction for the linear
interpolation of the declination of the sun for the time that an
observation is taken. This error is usually negligible, but is
removed when this is checked. (This should only be checked
when performing sun shots.)
• ;
Correct to State Grid : when selected, the computed
azimuth is referenced from the local State Plane grid rather
than true north.
• ;
Center Meridian / Zone Constant : these values are used to
adjust the computed azimuth to the local State Plane grid.
Appendix A lists these values for the United States.
GHA0 : is the Greenwich Hour Angle of the sun at zero hour Universal
Time, Greenwich, on the current date.
Decl0 : is the declination of the sun at zero hour on the current date.
GHA24 : is the Greenwich Hour Angle of the sun at zero hour
Universal Time, Greenwich, on the following day (24-hours later).
Decl24 : is the declination of the sun at zero hour on the following day.
Solar Semi-Diameter : is the semi-diameter of the sun, expressed in
minutes and seconds.