The Observed Velocity Structure of the Lunar Sodium Tail

We have recently obtained the first velocity resolved sodium 5889.950 Å\ (D2) line profile observations of the extended lunar sodium tail observed in the anti-lunar direction within 2--14 hours from new Moon. These observations were made on 29 March 2006, 27 April 2006 and 28 April 2006 from Pine Bluff (WI) Observatory (PBO) with a double etalon Fabry-Perot spectrometer. The PBO Fabry-Perot is coupled to a siderostat with a circular 1.5° field-of-view on the sky, and is capable of sampling a 75 km s-1 spectral interval with ~ 3.5 km s-1 spectral resolution at 5890 Å. The average observed radial velocity of the lunar sodium tail in the vicinity of the anti-lunar point for the three nights reported was 12.4 km s-1 (from geocentric zero). The average Doppler width of a single Gaussian fit to the emission line was 7.6 km s-1. In this poster we will explore the spatial variation in the velocity structure of the emission which was mapped over a ~ 8° field on the sky using a grid of observations with steps of 6m in right ascension (α) and 1.5° in declination (δ).