NED object is MESSIER 082; Reference is 1977MNRAS.178..577C

   Figure 2. The high-resolution (2 arcmin) integrated hydrogen map of M82 with
 the same contour interval as in Plate 2. The central cross and 'hole' are
 respectively the continuum centroid position and full beam area within which H
 I emission is unobservable. South of the nucleus some knots in the bridge can
 be seen. Rms noise is 41 K km per second at the map centre, and the contour
 interval is 132 K km per second.