The Interstellar Band at λ4430 has been observed in over 100 stars by using the Lick Observatory scanning spectrograph mounted on both the 120-inch telescope and on the Crossley telescope. Although in some instances the feature is badly blended with stellar lines, particularly with early B supergiants, in general the central depth of λ4430 has been determined to an accuracy exceeding 0.5 percent of the stellar continuum.

The feature has been found to have a fairly symmetrical profile, although there may be changes in the profile from star to star. The extended wings reported by other observers were not detected, and also the feature does not seem to be polarized.

The correlation between the absorption band at A.4430 and color excess is not one-to-one. Even field stars lying in the galactic plane show much intrinsic scatter in the ratio of this absorption band to color excess.