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Refractional flattening of sun or moon
From: Marcel Tschudin
Date: 2010 Apr 3, 10:57 +0300
From: Marcel Tschudin
Date: 2010 Apr 3, 10:57 +0300
In the thread "Sun Moon Lunars to 155 degrees" Antoine mentions that this effect should be included when clearing navigational observations. My first reaction was "no", at least not more than what you do by considering the refraction obtained from one of the various empirical transfer-functions which calculate the refraction as a function of altitude. It is the highly non-linearity of those functions near the horizon which cause this flattening. The refraction at the LL is higher than at the UL, the flattening is thus caused by the refraction difference which is already considered when using one of those transfer-functions. However, Frank mentions in his reply: "Today, oblateness and refractional flattening are as easy to include as any other aspects in the lunars clearing process so by default they are "on" in the clearing tool on my web site." What do you mean here Frank? Are you really doing more than just applying the "normal" refraction? Could it be that you eventually correct the empirical refraction values obtained from the transfer-function according to e.g. the body's height to width ratio measured at different altitudes? Marcel