Example HIRES data showing the three oxygen emission lines identified in individual 5-minute integrations. Calibrated brightnesses reported in this study assume emission from Europa’s apparent solid angular disk; consequently, the brightness distribution in the images appears lower due to blurring from atmospheric seeing and the presence of any extended coronal emission. White graticules show the physical size and orientation of Europa, with north oriented approximately upward. Dashed lines show the prime meridian. Telescope pointing accuracy was not sufficient to determine the position of the emission relative to Europa’s apparent disk, so we centered the images and graticules on the brightness centroids to illustrate the relative extent of the emission. Gray circles in the lower left corner show the typical Maunakea seeing FWHM of around 0﹩\mathop{.}\limits^{^{\prime\prime} }﹩6 (see statistics compiled at http://mkwc.ifa.hawaii.edu/forecast/mko/stats/). The HIRES images for each of the three oxygen emission lines are available in FITS format in a .tar.gz package.

(The data used to create this figure are available in the online article.)

(The data used to create this figure are available.)