The Height and Geographical Position of the Red Auroral Arc of

Simultaneous observations of an auroral arc from Cactus Peak, California, and Fritz Peak, Colorado, on the night of April 1–2, 1960, have provided the information necessary to determine the height of maximum luminosity and the geographical position of the arc. Twenty pairs of measurements determine the average height to be 425 km with a standard deviation of ±22 km from the average for a single pair of observations. The arc, observed from a point over the Pacific Ocean off the Oregon Coast to a point over the state of Mississippi, lay generally along a line of equal magnetic inclination.