(883607) 2016 TA56: an outer dark comet candidate, and the 2007 precovery its acceleration rests on

The near-Earth asteroid (883607) 2016 TA56 moves on a Jupiter-family orbit (T_J = 2.69), and JPL's current orbit solution carries a transverse non-gravitational acceleration A₂ = (−3.19 ± 0.36) × 10⁻¹² au d⁻² (8.9σ) on the standard cometary g(r) law. That is about twenty times a generous Yarkovsky ceiling for a body of its brightness (H = 18.13). No coma has been reported. By the definition of Seligman et al. (2024) it is a candidate outer dark comet, and it is not among the fourteen they list. The detection depends on the 2007 September 14 CFHT precovery: fitted to 2016–2026 alone, with radial and transverse terms free, the arc does not detect the acceleration. We re-measured that night on the archival MegaPrime frames against Gaia DR3, confirmed six of the eight archived positions to 0.1″, found the object on four frames never reported, checked the frames' clock on numbered asteroids in the same field (right to within half a minute), and found the night's brightness within about 0.3 mag of the prediction from H. The object is observable to large telescopes until about the end of 2026.