Cargolux 747, DB-8 ATN502, BOE372
Special visit from ATN502, a DC-8 that doesn't normally land at BFI, but was glad to see it despite the clouds.
Cargolux CLX772 flew over as well.
BOE372, July 19, around 11:30am. Pretty far away, enroute to KBFI. Can't make out any markings, unfortunately.