Light of Webb's Planetary Nebula (DM. + 41° 4004)

Abstract

THE recent discovery by the Rev. T. W. Webb, that the star DM. + 41° 4004 is a planetary nebula, and the attention which has consequently been attracted to this object, induce me to send herewith the result of a measurement of its light made at the Harvard College Observatory. Observations are in progress upon the light, dimensions, and spectra of all known planetary nebulæ visible in this latitude. To avoid the repetition of similar errors, two or three observers take part in the work, and each makes only one series of observations upon the same nebula in a single evening.