Further Note on the Color Curve of the 12-Inch Equatorial of the Lick Observatory

Edith E. Cummings, Priscilla Fairfield
1920 Publications of the Astronomical Society of the Pacific  
Equatorial oe the Lick Observatory In the February, 1919, number of these Publications an account was given of an investigation of the color curve of the objective of the 12-inch equatorial of the Lick Observatory. In pursuance of the plan mentioned there, we took further measures on the nights of July 16th and 17th, to obtain a more accurate determination of the temperature equation. The method of observing was the same as that described in-the previous paper, and the position of the slit with
more » ... respect to the base plate was measured as before. Six complete sets of measures by the Foucault method were taken, three by each observer; the mean temperature was + 25°.o C. The resulting "high temperature" color curve is parallel to those for lower temperatures, with a constant difference of 1.67 mm. between this and the curve for 4°.6 C. Thus the temperature equation, as determined from a range of 2i°.4 is R = R 0 + 0.08 mm. (t -9°.i), which is identical with the equation obtained before from a range of 9 0 .
doi:10.1086/123016 fatcat:uefxm22tmba67pow3lbur5i4be