DARK HYDROGEN IN THE GALACTIC PLANE Steven J. Gibson, 1 A. Russell Taylor, 1 Jeroen M. Stil, 1 Lloyd A. Higgs, 2 Peter E. Dewdney, 2 & Christopher M. Brunt 2 1 University of Calgary 2 Herzberg Institute of Astrophysics Abstract New high­resolution surveys reveal an abundance of cold H i features in the Galactic plane. ... Top: VLA Galactic Plane Survey H i channel map of a fan­shaped  1 ф HISA complex in the inner Galaxy. ... associated CO, most outer Galaxy HISA does not [3, 4, 7]. ...

... 2.3 Data acquisition Spectra generated by the Multibeam correlator contain the usual structure seen in spectra from other H i instruments: a bandpass spectrum which is the sum of the sky , ground and receiver temperatures multiplied by the product of the filters in the receiver chain; superimposed on this is a noise ... Note also that sources extended much beyond ,40 arcmin can be imaged poorly in HIPASS images because of the bandpass sidelobe effect described in Section 3.3. ...