The diffuse interstellar bands. VI - New features near 6800 A

A group of about 29 weak lines lying between 6767 and 6862 A has been found on high signal-to-noise ratio (S/N) scans of reddened stars. They have been observed in stars between types O3 and A5, do not appear in unreddened stars of those types observed with the same equipment, and strengthen with icreasing E(B-V). For these reasons, they are believed to be interstellar. Although narrow, they are not perfectly sharp at a resolution of 35,000. Five or six of the stronger features are nearly uniformly spaced at intervals of 35/cm, which is suggestive of the spacing expected for rotational structure of light hydrides such as CH, NH and OH, but no plausible carrier of those species has been identified.