stars in our the Galaxy and other nearby stellar groups.

Although there is some uncertainty in the number of bona fide SX Phe stars in our survey, the discrepancy between the numbers of SX Phe stars predicted in our Galaxy and nearby stellar systems is over an order of magnitude. The fact that SX Phe stars are less abundant in our Galaxy is presumably a consequence of the metallicity and star formation history of these systems. A comprehensive study of the number of SX Phe stars in different environments could lead to a better understanding of how these stars are formed.

Conclusions
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We have identified 31 blue pulsating objects for which we have evidence that they are candidate SX Phe or $\delta$ Sct stars. These pulsators which have periods between 51–83 mins are well suited to being discovered using surveys like RATS which have high cadence but have a relatively short overall duration. Unlike the RR Lyrae stars which have a longer pulsation period and corresponding brighter absolute magnitude, they have been little used to identify Galactic sub-structure. Our results suggest that existing survey telescopes would be well suited to the discovery of SX Phe and $\delta$ Sct stars 