Fig. 10

Zero-order (left) and spectral (right) images of β Cet (Diphda, 2nd in V-magnitude) observed by our spectral camera and the telescope on Nov. 9, 2017. One hundred frames were averaged, and the grayscale is inverted. We flipped the frames horizontally to show the spectral image right side of the zero-order image. The star was around a meridian transit at 54° in zenith angle. a The zenith is up in the image, corresponding to Fig. 9b. b We rotated the camera, and the zenith is the left-hand side, corresponding to Fig. 9c