Arlin died peacefully on Thursday 19th November after a long battle with cancer.
Arlin received his A.B. in Physics from Princeton University and his Ph.D. in Physics from the University of Chicago. On the Columbia Astronomy Faculty since 1991, he received a Packard Fellowship for Science and Engineering and the AAS's Newton Lacy Pierce Prize for outstanding achievement in observational astronomy. He made contributions in an unusually wide range of areas, addressing each topic with his characteristic daring and flare---from supernova light echoes in the Magellanic Clouds and nearby galaxies, to pixel-scale microlensing in Andromeda, to absorption lines in pairs and groups of quasars, to building giant liquid mirrors for telescopes, to finding water on the moon. The review in Nature of his 2014 book, The New Moon, noted that, "Arlin Crotts mines lunar research and its implications for human colonization in staggering, often deeply engaging, detail.'' As someone who valued intellectual discourse, Arlin was a fixture at our bi-weekly coffee hours where he delighted in discussing the latest scientific discoveries with professors and students alike. Occasionally the conversation would also turn to human space exploration and the development of rockets, the history of science, his latest movie project, or the state of the world. His strong presence in the department, his sharp mind, and his quirky laugh and sense of humor will be sorely missed.