  We consider the acoustic source imaging problems using multiple frequency
data. Using the data of one observation direction/point, we prove that some
information (size and location) of the source support can be recovered. A
non-iterative method is then proposed to image the source for the Helmholtz
equation using multiple frequency far field data of one or several observation
directions. The method is simple to implement and extremely fast since it only
computes an indicator function on the interested domain using only matrix
vector multiplications. Numerical examples are presented to validate the
effectiveness of the method.
