TEMPERATURES OF MARS, 1926, AS DERIVED FROM THE WATER-CELL TRANSMISSIONS

Abstract

opposition by Coblentz and Lampland at Lowell Observatory1 were sent to Menzel at Lick Observatory for an independent reduction. The water-cell transmissions were reduced in the customary manner2, the results being given in Table I. The date of the observation is noted in column 1. Owing to the improved design of the thermocouple, observations of smaller areas could be made than ever before. Settings were made upon the center and the East, West, North and South limbs. The respective regions are denoted in the table by the letters C.,E.,W.,N., and S. When the planetary image was large enough to permit, observations were also secured at points midway between the center and the four limbs. These results are labelled E. C. (east central), W. C, N. C, and S. C. The first column under each region contains the observed water-cell transmission (percentage), the second the temperature derived from it expressed in degrees on the absolute scale. The focal length and aperture used, as well as the ratio of the diameter of the receiver to that of the planet are noted. The results are generally quite in accord with those already published. The present series of observations was begun on October 7, 1926, when the planet's phase was 24°, and concluded November 5, one day after opposition. The Martian summer, which started August 24, was well under way, and we should expect higher temperatures than for the last opposition, which happened almost concurrently with the Martian solstice. We find this to be the case, but the observed temperature difference, 15° to 20°C, is almost too great to be accounted for by the above simple explanation. Part of the discrepancy is to be attributed