Scintillation Correlations in the Near‐Infrared

Abstract

ABSTRACT. Stellar scintillation has been measured from 0.9 to 1.7 mm over a wide range of elevation angles. The pupil from a 3.5 m telescope was imaged onto a mask with four circular apertures of scaled diameters 0.1, 0.2, 0.75, and 1.5 m, which were, in turn, reimaged onto InGaAs photodiodes digitally sampled at 10 kHz. The entire 3.5 m pupil was also imaged onto a fifth photodiode. Since all five fluxes were recorded simultaneously, the influence of aperture diameter on scintillation statistics can be readily seen. Atmospheric phase aberrations did not affect the results because the detectors were located at pupil planes. Comparisons of a large number of fluctuation statistics have been made as functions of the aperture diameter, atmospheric parameters, and elevation angle. Experimental results and theoretical expectations reveal widespread agreement. Within experimental error, lognormal statistics are followed. Scintillation in the near-IR has been shown to produce consistent results with previous studies performed at visible wavelengths.