An alternative approach to modelling a cosmic void and its effect on the
  cosmic microwave background
  We apply our tetrad-based approach for constructing spherically-symmetric
solutions in general relativity to modelling a void, and compare it with the
standard Lema\^itre-Tolman-Bondi (LTB) formalism. In particular, we construct
models for the void observed in the direction of Draco in the WISE-2MASS galaxy
survey, and a corresponding cosmic microwave background (CMB) temperature
decrement in the Planck data in the same direction. We find that the
present-day density and velocity profiles of the void are not well constrained
by the existing data, so that void models produced from the two approaches can
differ substantially while remaining broadly consistent with the observations.
We highlight the importance of considering the velocity as well as the density
profile in constraining voids.
