Latent image
When bright objects are present in one image, images obtained soon afterward will have faint "residual" images at the same position in the array. SSC will provide an estimate of latent image level. We don't expect it to be a big concern with our 2 sec exposures.
To create our test latent image we took a 256 x 256 pixel section from a corner of one of the original 512x512 star field, added a background, and multiplied the intensity of all the pixels by 0.01%.