
%0 Journal Article
%A Reif, Klaus 
%A Stark, Ronald 
%T Surface Brightness Measurements of Extended Galactic Nebulae
%J Publications of the Astronomical Society of Australia
%D 1998/04/01
%V 15
%N 1
%P 86-90
%K 
%R https://doi.org/10.1071/AS98086
%U https://www.publish.csiro.au/paper/AS98086 
%X We discuss the importance of digitised sky-limited Schmidt B- and R-band, and Halpha images of extended translucent (A_B ~ 1-5 mag) and dark (A_B > 5 mag) clouds. In translucent clouds (e.g. high-latitude cirrus) photons can penetrate through the whole cloud and control the physical and chemical processes. Comparison of the B images with far-infrared/submillimetre CO, CI, and CII emission provides important information on the non-homogeneous cloud structure, carbon chemistry and energy balance. In dark clouds the interior is completely shielded from the interstellar radiation field. L1204 is a dark cloud with at its edge the well-known HII rim S140. The R-band image shows S140 as well as the diffuse extended HII region around the exciting B-type star. However, the sensitivity for Halpha in the R-band is rather low and there is contamination with diffusely scattered red light from dust. Deep Halpha and R-band imaging of an ~20'x20' field has recently been done with the 1 m Hoher List telescope of Bonn University. A wealth of small-scale structures can been seen on continuum-subtracted images which provide new insight on the geometry of this cloud. 
