  We study the twisted-Hopf-algebra symmetries of observer-independent
canonical spacetime noncommutativity, for which the commutators of the
spacetime coordinates take the form [x^{mu},x^{nu}]=i theta^{mu nu} with
observer-independent (and coordinate-independent) theta^{mu nu}. We find that
it is necessary to introduce nontrivial commutators between transformation
parameters and spacetime coordinates, and that the form of these commutators
implies that all symmetry transformations must include a translation component.
We show that with our noncommutative transformation parameters the Noether
analysis of the symmetries is straightforward, and we compare our
canonical-noncommutativity results with the structure of the conserved charges
and the "no-pure-boost" requirement derived in a previous study of
kappa-Minkowski noncommutativity. We also verify that, while at intermediate
stages of the analysis we do find terms that depend on the ordering convention
adopted in setting up the Weyl map, the final result for the conserved charges
is reassuringly independent of the choice of Weyl map and (the corresponding
choice of) star product.
