After a lot of searching I cannot for the life of me find the transformation for a Momentarily Co-moving Reference Frame. Essentially what I'm looking for is the transformations from inertial frame Sigma to inertial frame Sigma[']. Sigma['] is moving at speed v relative to Sigma not along any axis in Sigma. The origins of the inertial reference frames do not coincide at t=t'=0, so I cannot use the general Lorentz transforms. Does anyone have any idea where to find the elements of the Poincare transform. Any help is greatly appreciated. Thanks in advance, Andrew.