The L1 point of the Earth-sun system was located on a straight line between those two bodies. Ymir, for all practical purposes, was at L1. So, generally speaking, when Izzy swung around the dark side of the Earth and emerged into the sunlight, it meant that they could "see" L1, and communicate with Ymir . This next occurred at about 7:30 A.M. Greenwich time, which happened to be sunrise in London. Dinah, gazing down out her little window, was able to see the terminator—the dividing line between the day and night sides of Earth—creeping over the Thames estuary down below, and lighting up a few tall spires in the London financial district. Then she turned to her telegraph key, established contact with Ymir, and tapped out her message. This ended up consuming the entire transmission window. She had to send the characters very slowly, because Sean wasn’t very good at reading Morse code. And because the message was encrypted, he wasn’t able to guess missing letters from context, and so every letter had to be read clearly. By the time she was finished, Izzy had swung almost halfway around the world and was about to plunge back into night. She finished her transmission with TBC, which she hoped they would understand as "to be continued," then went right back to work writing and encrypting a supplement.