MUSE is the Multi Unit Spectroscopic Explorer, an AO-assisted integral field spectrograph for visible and
near-IR wavelengths which is planned to be commissioned at the UT4 of the Very Large Telescope in 2012.1 We
present the status on the modeling of the spatial PSF at the UT focus and its Field-of-View (FoV) and spectral
variations. Modeling these variations and studying their implications is a cornerstone for some MUSE data
analysis and processing problems such as fusion, source extraction and deconvolution of MUSE datacubes.
In Wide Field Mode (WFM, 1 square arc-minute FoV, 0.2 arcsec spatial sampling), MUSE can operate
without Adaptive Optics (AO) correction or with a Ground Layer Adaptive Optics facility aimed at providing
an almost uniform correction over a large field of view. In Narrow Field Mode (7.5 square arcseconds FoV, 0.025
arcsec spatial sampling) MUSE will make use of a Laser Tomography Adaptive Optics reconstruction, implying
stronger spatial variations. By using the adaptive optics simulation tool PAOLA, we simulate in WFM the
spatial PSF as a function of atmospheric turbulence parameters, observed wavelengths, AO mode and position
in the field of view. We then develop a mathematical model fitting the generated data which allows, with a small
number of parameters, to approximate the PSF at any spatial and spectral position of MUSE datacube. Finally,
we evaluate the possibility to estimate the model parameters directly from the (future) MUSE data themselves.