NEUTRAL HYDROGEN ABSORPTION AGAINST SUPERNOVA-REMNANTS IN M82

We present MERLIN neutral hydrogen absorption measurements against sup ernova remnants in the central starburst region of M82 with an angular resolution of similar to 0.4 arcsec. We detect H I absorption or set significant upper limits against 33 supernova remnants from which we h ave been able to deduce column densities. Hence, using these measureme nts, we are able to probe the neutral hydrogen distribution and dynami cs of the interstellar medium in M82 along 33 lines of sight on linear scales of order 1 pc. Our results show column densities ranging from <1.6 to >30 x 10(21) atom cm(-2) with the highest values seen towards the edge of the 250-pc 'ring'. The absorption velocities show a gradie nt of 7.3 +/- 4 km s(-1) arcsec(-1), consistent with rotation paramete rs of this 'ring' inferred from other measurements. The absorption vel ocities against individual remnants show deviations of typically 30 km s(-1) from simple solid body rotation, and a number show multiple vel ocity absorption features. Although some of these deviations may be th e result of the remnants being embedded at different depths within the neutral gas, the velocities cannot be explained by a simple rotating ring.