On large telescopes trails of MegaConstellation's satellites will appears significantly defocused because of their relatively short distance. Because of such effect their apparent surface brightness will be, under a range of conditions, almost constant during their apparent sweeping on the focal plane of such large facilities. A few simple relationships are worked out and discussed to show the apparent brightness of such trails, in order to evaluate their impact on operations of large optical ground based facilities.
@article{arxiv.2007.00609,
title = {The surface brightness of megaconstellation satellites trails on large telescopes},
author = {Roberto Ragazzoni},
journal= {arXiv preprint arXiv:2007.00609},
year = {2020}
}