2005A&A...434..585N

We present 1.2mm continuum data of the filamentary dark cloud Sandqvist 187/188 - also known as the Norma cloud - taken with SIMBA (SEST Imaging Bolometer Array). The data are complemented by measurements from the 2MASS, MSX and IRAS surveys. The extended 1.2mm emission traces the optical dark cloud down to a visual extinction of A_V=3.7mag. We derive a mean column density of N(H₂)=1.4x10²²cm^–2, equivalent to a visual extinction of A_V=7.6mag and a total mass of the cloud of 340M_☉. We also find six compact millimetre sources, labelled MMS 1 to 6, five of which coincide with known stellar objects. MMS 6, however, only has a very weak MSX counterpart at 14.56µm and an absorption feature at 8.28µm consistent with a visual extinction of A_V>145mag. Dust temperatures, luminosities and gas masses for all compact millimetre sources are given. In an effort to further constrain the uncertain distance to Sandqvist 187/188, we analyse its stellar content based on 2MASS colours and find an improved lower limit of 440±50pc.