In adaptive optics systems employing laser guide stars, the tip/tilt contribution to the long exposure point spread function must be estimated separately from the high-order tip/tilt removed point spread function because this component is estimated separately from a single or multiple low-order natural guide star wavefront sensors. This paper investigates this problem for laser guide star multi conjugate adaptive optics. The approach is based on the scheme developed by Flicker in 2003, and consists in post-processing the measurement covariance matrix of multiple low-order natural guide star wavefront sensors controlling tip/tilt and tilt anisoplanatism. An innovative simulation model based "balanced" algorithm is introduced to capture error terms not accounted for in Flicker's algorithm. Sample enclosed energy results for the Thirty Meter Telescope multi conjugate adaptive optics system demonstrate the superiority of the balanced method and call for further analytical work and experimental validation
