Fig. 10

A sample of high spatial resolution dayside 2.02-µm images from the IR2 camera, each at a pixel scale of approximately 5 km in the calibrated (left column, a, c, e) and contrast filtered versions (right column, b, d, f). The quadrant boundaries of the CCD can be faintly seen in the calibrated version due to slightly different gains of the readout electronics. Very bright pixels in the contrast filtered versions represent noise pixels. Very subtle sinuous or string-like structures are seen with widths of about 20–40 km and with variable lengths and inclinations to latitude circles as seen in a and b. Image b shows bow-like waves also seen at ultraviolet wavelengths. Image e is devoid of such patterns, but instead shows a bright area surrounded by a poorly defined dark ring, which results from low-frequency electronic noise due to the cross talk between the readout electronics of the four quadrants of the image. This pattern disappears in the contrast filtered version (f). It is interesting that the thin wavy streaks seen in b and d are absent in f which has almost twice the spatial resolution, similar to the difference at the shorter wavelengths (images b and f in Fig. 9)