While quality checking a new motion-aware co-addition of all 12.5 months of WISE data , the source WISE J070720.48+170533.0 was found to have moved 0.9 ^ { \prime \prime } in 6 months .
Backtracking this motion allowed us to identify this source as 2MASS J07071961+1705464 and with several entries in the USNO B catalog .
An astrometric fit to these archival data gives a proper motion of \mu = 1793 \pm 2 mas/yr and a parallax of \varpi = 35 \pm 42 mas .
Photometry from WISE , 2MASS and the POSS can be fit reasonably well by a blackbody with T = 3658 K and an angular radius of 4.36 \times 10 ^ { -11 } radians .
No clear evidence of H _ { 2 } collision-induced absorption is seen in the near-IR .
An optical spectrum shows broad deep CaH bands at 638 & 690 nm , broad deep Na D at 598.2 nm , and weak or absent TiO , indicating that this source is an ultra-subdwarf M star with a radial velocity v _ { rad } \approx - 21 \pm 18 km/sec relative to the Sun .
Given its apparent magnitude , the distance is about 39 \pm 9 pc and the tangential velocity is probably \approx 330 km/sec , but a more precise parallax is needed to be certain .