We report a deep search for 21 cm emission/absorption from the z \sim 0.101 candidate damped Lyman- \alpha system towards PKS 0439 - 433 , using the Australia Telescope Compact Array ( ATCA ) .
The spectrum shows a weak absorption feature — at the 3.3 \sigma level — which yields a lower limit of 730 K on the spin temperature of the system .
No H i emission was detected : the 3 \sigma upper limit on the H i mass of the absorber is 2.25 \times 10 ^ { 9 } M _ { \odot } , for a velocity spread of \sim 70 km s ^ { -1 } .
The low H i mass and the high spin temperature seem to rule out the possibility that the absorber is a large gas-rich spiral galaxy .