  Radiative nucleon-deuteron capture and photo disintegration of the
three-nucleo n bound state with two-body final states are described. The
description uses nucleon degrees of freedom extended to include the excitation
of a single nucleon to a \diso. The baryonic interaction and the
electromagnetic cu rrent couple nucleonic states and states with a \diso. Exact
solutions of three-p article scattering equations are employed for the initial
or final states of the reactions. The current has one-baryon and two-baryon
contributions. The role of t he \diso in the description of the considered
photo reactions is discussed and fo und to be moderate. The spin observables
$A_{yy}$ and $T_{20}$ at $90^{\circ}$ la b scattering angle can be calculated
model-independently from the $E1$ Siegert te rm in the long-wavelength limit.
