“selected photographs of the sun, taken with the Hydrogen Alpha 1 Telescope aboard the ATM Skylab during the manned portions of SL2, SL3, and SL4. The purpose of the Atlas is to provide readily accessible pointing information and solar feature identification to scientists evaluating the data of ATM experiments." -- ‘Harvard College Observatory, Apollo Telescope Mount, Hydrogen Alpha Telescope, Film and Atlas Guide’, by Darrel Torgerson.