Refraction

For the calculation of refraction-corrected topocentric coordinates (see Ephemeris Type Selection), select Ephemeris -> Refraction from the main menu. In the appearing Refraction dialog check Correct for refraction. Temperature and Atmospheric pressure at the place of observation are required for the computation of refraction. If other than the default values, shown in the picture of the page, are to be used, enter the temperature in degrees Celsius and the pressure in millibars. Click OK, and all contents of the dialog are retained and used for ephemeris computation whenever topocentric coordinates are selected. For informational purposes the table in the Refraction dialog provides values of refraction corresponding to the settings for temperature and pressure at different altitudes. When correction for refraction is performed and topocentric coordinates are selected, the word 'refraction' appears in the status bar.      To open the Refraction dialog, click refraction field in status bar.