These simulations are very similar to those described earlier for SXT images . Angstrom Fe XV band. Results seem to confirm previous worries about limitations of the AEC algorithm as it was initially implemented . It is anticipated that these limitations can be overcome by very simple modifications to the software. Lyman alpha seems to show no high intensity tail and is therefore not a problem.
Exposure time is specified by an integer index to the exposure table.
The AEC algorithm adjusts the exposure index based on a 128-bin histogram of the previous CCD image, which is taken after the removal of bad pixels. If the image is simultaneously overexposed and underexposed according to the criteria set up by the AEC table parameters, then the algorithm reacts conservatively by decreasing exposure time. The NIXT image was calibrated to intensity units using a procedure supplied by Ed Deluca. Results are presented in the next three sections for three parts of the NIXT full disk image. The key thing to note in each case is the number of saturated pixels.