The bistatic geometry for Na profiling with LGS at Teide Observatory

We develop an algorithm to retrieve mesospheric Na profiles from the ESO-IAC LGS experiment at Teide Observatory (OT). We are using a bistatic configuration for Na LGS profiling between the ESO Wendelstein LGS Unit (WLGSU) and the IAC80 telescope with a baseline of 126 m. We describe the geometry of the problem and discuss the errors. The inputs are the observer pointing coordinates and the azimuth of the launcher, avoiding the refraction effect on the beam. Accuracy in the coordinates is a must and the images should be astrometrized. With an accuracy of 1 " in the launcher azimuth, the absolute Na heights can be obtained with a resolution better than 200 m (ZD=40 degrees). We also propose a double observer telescope, 90 degrees shifted, to avoid the effect of a divergent solution when launching in the azimuth subtended between observer and launcher.