  Deflection of light due to massive objects was predicted by Einstein in his
General Theory of Relativity. This deflection of light has been calculated by
many researchers in past, for spherically symmetric objects. But, in reality,
most of these gravitating objects are not spherical instead they are
ellipsoidal ( oblate) in shape. The objective of the present work is to study
theoretically the effect of this ellipticity on the trajectory of a light ray.
Here, we obtain a converging series expression for the deflection of a light
ray due to an ellipsoidal gravitating object, characterised by an ellipticity
parameter. As a boundary condition, by setting the ellipticity parameter to be
equal to zero, we get back the same expression for deflection as due to
Schwarzschild object. It is also found that the additional contribution in
deflection angle due to this ellipticity though small, but could be typically
higher than the similar contribution caused by the rotation of a celestial
object. Therefore for a precise estimate of the deflection due to a celestial
object, the calculations presented here would be useful.
