The unambiguous 2-D horizontal wave number spectrum of gravity wave perturbations in OH emission intensities is computed from imager observations acquired on 2 Feb 1995 at the Starfire Optical Range, NM. The technique involves computing the (&ohgr;,k,l)=(&ohgr;,h,ϕ) spectrum of OH images collected over a several hour period, where k is the zonal wave number, l is the meridional wave number, h=(k2+l2)1/2, ϕ=tan-1(k/l), and &ohgr; is the temporal frequency. The data are used to study the azimuthal distribution of wave energy propagation and the separability of the (h,ϕ) spectrum. The h spectral indices, computed from power-law fits of the 2-D spectrum over the wave number range 2&pgr;/(200 km)<h<2&pgr;/(20 km), vary between -1.6 and -3.6 as a function of ϕ with a mean of -2.58. Consequently, the image spectrum is not separable in h and ϕ. We show that nonseparability is most likely associated with distortion of the wave perturbations caused by the viewing geometry at large zenith angles. ¿ American Geophysical Union 1996