Observations of cold extragalactic gas clouds at <i>z</i> = 0.45 towards PKS 1610-771

We present results from MUSE observations of a 21-cm HI absorption system detected with the Australian Square Kilometre Array Pathfinder radio telescope at redshift $z = 0.4503$ towards 1.71$ quasar PKS 1610-771. identify four galaxies (A, B, X and Y) same as H I Damped Lyman-{\alpha} (DLA) system, impact parameters ranging less than 10 kpc to almost 200 sightline. Ca II Na is seen in spectrum background QSO, velocities coinciding initial detection, but tracing dense warmer gas. This metal-line component aligns rotating ionised disc galaxy B (impact parameter 18 QSO) appears be co-rotating disc. In contrast, absorber blueshifted relative nearest has opposite sign velocity field B. Since A are separated by only 17 on sky $70$ km s$^{-1}$ velocity, it likely that detection traces extragalactic clouds gas formed their interaction. reveals cold 100 K neutral critical for star formation can associated complex structures beyond disc, first case study made preparation future large surveys like ASKAP First Large Absorption Survey HI.