Auroral research at the Tromsø Northern Lights Observatory: the Harang directorship, 1928–1946

The Northern Lights Observatory in Tromsø began as Professor Lars Vegard's dream for a permanent facility in northern Norway, dedicated to the continuous study of auroral phenomenology and dynamics. Fortunately, not only was Vegard an internationally recognized spectroscopist, he was a great salesman and persuaded the Rockefeller Foundation that such an observatory represented an important long-term investment. A shrewd judge of talent, Vegard recognized the scientific and managerial skills of Leiv Harang, a recent graduate from the University of Oslo, and recommended that he become the observatory's first director. In 1929, subsequent to receiving the Rockefeller Foundation grant, the University of Oslo established a low temperature laboratory to support Vegard's spectroscopic investigations. <br><br> This paper follows the scientific accomplishments of observatory personnel during the 18 years of Harang's directorship. These include: identifying the chemical sources of auroral emissions, discovering the Vegard&ndash;Kaplan bands, quantifying height distributions of different auroral forms, interpreting patterns of magnetic field variations, remotely probing auroral electron distribution profiles in the polar ionosphere, and monitoring the evolving states of the ozone layer. The Rockefeller Foundation judges got it right: the Tromsø <i>Nordlysobservatoriet</i> was, and for decades remained, an outstanding scientific investment