SIMBAD references

The distribution of the interstellar dust toward the northern part of the Coalsack, and its surrounding, is investigated on the base of the colour excess and distances estimated from Stroemgren photometry for a sample of stars earlier than G0, and belonging to the Selected Area 194. The analysis indicates that the interstellar medium along the observed directions is composed by a low column density material up to distances of about 150pc (average colour excess E(b-y)≃0.014mag ). Beyond that distance, one notices the effect of a higher column density material on the observed colour excesses. Such effect may be due in part to dust in the Coalsack. The colour excess for stars within the distance interval 200pc to 1100pc shows a well defined minimum of E(b-y)≃0.100mag , while beyond that distance another minimum of E(b-y)≃0.200mag is reached.