from M3 (Jordi & Grebel 2010). The other source of particular note is J0305 which is located in the direction of the Galactic anti-center and at a distance of 30kpc (implying a Galactocentric distance of 38 kpc) and a height of 21 kpc below the Galactic plane. Recent work shows that the stellar density of the Galaxy decreases sharply at Galactocentric distances greater than 25 kpc (eg Watkins et al 2009, Sesar et al, 2010) which may indicate that J0305 is associated with a sub-structure of the halo. Alternatively it may be in the process of being ejected from our Galaxy. A more detailed radial velocity study is required to answer this question.

The Galactic population of SX Phe stars
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SX Phe stars have been identified in globular clusters and nearby dwarf galaxies (eg Olech et al 2005, Poretti et al 2008). Based on the number of blue stellar pulsators which we have identified in our survey, we now make an estimate of the total number of SX Phe stars which are present in our Galaxy. Since our survey is biased towards low Galactic fields, highly reddened (but intrinsically blue) pulsators could be confused with apparently much redder sources 