He identified the first Miras in the Magellanic Clouds, leading to the discovery that these variables obey a tight period-luminosity relation (Glass & Evans, 1981).
A period-luminosity relation for Mira variables in the Large Magellanic Cloud, Nature, 291, 303- 304.
Systematic errors such as whether chemical composition differences among Cepheids might affect the period-luminosity relation
, will be examined using the infrared data.
Yet even today the calibration of the Cepheid period-luminosity relation
remains somewhat unsettled, especially in light of new star distances measured by the Hipparcos astrometry satellite.
Parallaxes were obtained for several types of pulsating variables, and data from 20 Cepheids will be used to reexamine the basic assumptions behind the period-luminosity relation
for these celestial yardsticks.
Some of the early photographic and visual catalog projects rivaled the Henry Draper Catalogue of spectra in accuracy and scope and led directly to the discovery of the interstellar medium, the Cepheid period-luminosity relation
, and precise maps of galactic structure.
Variations in the period-luminosity relation
induced by differences in chemical composition will be calibrated.