A piggyback search is a SETI technique that does not require the dedicated use of a radio telescope. Instead, during routine astronomical observations, a computer program automatically checks for narrowband signals of the type that are unlikely to arise from natural objects in space. This approach means that the search is restricted to whatever wavelengths and parts of the sky are of interest to the astronomers, but as there is no way of ensuring where best to look in the first place this is no great disadvantage. On the contrary, it avoids what might otherwise be a human bias in the choice of target.