  We have earlier proposed a fourth order gravity model as a possible
explanation for late time cosmic acceleration, and for flattened galaxy
rotation curves. The model has a free length parameter whose value depends on
the scale of the system under study (e.g. the whole Universe, a galaxy, or a
compact binary pulsar). In the present work, we investigate the constraints
imposed on the free model parameter by Hulse-Taylor binary pulsar data:
periastron advance; and emission of gravitational waves and consequent period
decay. It is shown that the model is consistent with these observations,
provided the length parameter is bounded from above.
