DALLAS — The top lot of Heritage Auctions’ July 16 sale was a significant but somber souvenir from a pivotal moment in world history. Enola Gay co-pilot Robert A. Lewis’ logbook written on August 6, 1945, as he and his crewmates dropped the atomic bomb on the citizens of Hiroshima, sold for $543,000 to lead Heritage’s first Historical Platinum Session Signature® auction. This harrowing and oft-heartbreaking account of the very moments between the pre-atomic and post-atomic world was written at the request of New York Times reporter William L. Laurence. This 11-page logbook, which includes the unforgettable “My God What Have We Done…,” has not been seen since it was sold at auction in 2002. Price quoted includes buyer’s premium as reported by the auction house. For information, www.ha.com.