THIS SUBROUTINE COMPUTES ATMOSPHERIC REFRACTION IN ZENITH
DISTANCE. THIS VERSION COMPUTES APPROXIMATE REFRACTION FOR
OPTICAL WAVELENGTHS. IT CAN BE USED FOR PLANNING OBSERVATIONS
OR TELESCOPE POINTING, BUT SHOULD NOT BE USED FOR THE REDUCTION
OF PRECISE OBSERVATIONS. BASIC ALGORITHM IS DESCRIBED IN THE
EXPLANATORY SUPPLEMENT TO THE ASTRONOMICAL ALMANAC, P. 144,
AND IS AN ADAPTATION OF A FORMULA IN BENNETT (1982), JOURNAL
OF NAVIGATION (ROYAL INSTITUTE) 35, 255-259.
HEIGHT = HEIGHT OF OBSERVER IN METERS (IN)
ZDOBS = OBSERVED ZENITH DISTANCE IN DEGREES (IN)
REFR = ATMOSPHERIC REFRACTION IN DEGREES (OUT)
NOTE: HEIGHT IS NOT USED IF ENTRY REFDAT HAS BEEN CALLED
TO SPECIFY ATMOSPHERIC PRESSURE.
Nodes of different colours represent the following:
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.
Nodes of different colours represent the following:
Solid arrows point from a procedure to one which it calls. Dashed
arrows point from an interface to procedures which implement that interface.
This could include the module procedures in a generic interface or the
implementation in a submodule of an interface in a parent module.