NED object is MESSIER 081; Reference is 1977ApJ...211...47G

   Fig. 5a.- Map of the integrated H I over the M81/M82 region incorporating
 the results of Gottesman and Weliachew 1975. The resolution is 4.4 arcmin. The
 minimum contour unit is 10.8 X 10**(19) atoms cm**(-2) on the sky. Dashed
 contours, regions of higher intensity than might be indicated by the
 cross-hatching. The coordinate system is with respect to the center of M81.