Diffuse interstellar absorption bands between 2.9 and 4.0 μm

Observations of interstellar absorption bands between 2.9 and 4.0 μm of IRS7, the obscured 7 supergiant near the galactic centre, are reported which show a broad absorption trough with numerous discrete features stretching from 2.9 to 3.6 μm. Although no definite identification of the material producing this absorption is possible, there is some indication that complex organic molecules may be involved. (U.K.)