excerpt from

An intercomparison of ground-based millimeter, MGS TES, and Viking atmospheric temperature measurements: Seasonal and interannual variability of temperatures and dust loading in the global Mars atmosphere

by R. T. Clancy, B. J. Sandor, M. J. Wolff, P. R. Christensen, J. C. Pearl, B. J. Conrath, and R. J. Wilson

Journal of Geophysical Research, vol. 105, no. E4, page 9564

25 April 2000

edited by Thomas Gangale

For the purpose of this comparison, we use the solar longitude range 0°-360° to define a Mars year and adopt April 11, 1955 (LS=0°) as the beginning of year 1. In this arbitrary convention, the Mariner 9, Viking, Phobos, and Pathfinder missions occurred in years 9-10, 12-15, 19-20, and 23, respectively. By comparison, the 1992-1999 millimeter observations extend over years 21-24, and the 1997-1999 TES observations extend over years 23 and 24.