First observations of the granulation at 1.65μ, center to limb variation of the contrast

Brightness fluctuations at 1.65 have been recorded by means of a 64-element array. Infrared photographs clearly show sunspots and granulation with a resolution better than 1. Quantitative analysis of the digitized data is used to compute autocorrelation and power spectrum. Half-width of autocorrelation (405 km) indicates a resolution comparable with the best observations in the visible range. Photographs and quantitative analysis show the existence of a strong contrast variation from the center to the limb. Seeing and instrumental effects are discussed. A model M.T.F. is utilized to compute a foreshortening correction. No attempt is made to get the actual absolute rms value. Nevertheless we find a definite variation of the observed rms which goes from 1.48%±±0.15, at the center, to 1.05%±0.15 at = 0.7 (after foreshortening correction).