parallel algorithms for the determinant of the Hessenberg matrix
Sorry, this is clearly unlikely.
Otherwise, it would be possible to use the algorithm to solve any NL\poly
problem in NC1 via a reduction to evaluating the determinant of a Hessenberg matrix over a sufficiently large field.
The reduction appears as Lemma 3 (and related discussion) in
"Perfect constant-round secure computation via perfect randomizing polynomials".