Level3 Grid

[orifox]

Similar to Level2 data, it would be nice to have the ability to make a grid for Level 3. Something along the lines as follows below. A full notebook workflow can be found in grid_lvl3.ipynb in /astro/armin/data/space_phot_debug/ori

jwst3_obs = st_phot.observation3(lvl3[0])  
grid = st_phot.util.get_jwst3_psf_grid(jwst_obs3,num_psfs=4)  
psf3 = st_phot.util.get_jwst3_psf_from_grid(jwst3_obs,source_location,grid) 
jwst3_obs.psf_photometry(psf3,source_location,bounds={'flux':[-1000,10000],  
                        'centroid':[-2,2],
                        'bkg':[0,50]},
                        fit_width=5,
                        fit_bkg=True,
                        fit_flux=True)