We present a study of the ultra-faint Milky Way dwarf satellite galaxy Tucana II using deep photometry from the 1.3 m SkyMapper telescope at Siding Spring Observatory , Australia .
The SkyMapper filter-set contains a metallicity-sensitive intermediate-band v filter covering the prominent Ca II K feature at 3933.7 Å .
When combined with photometry from the SkyMapper u,g , and i filters , we demonstrate that v band photometry can be used to obtain stellar metallicities with a precision of \sim 0.20 dex when [ Fe/H ] > -2.5 , and \sim 0.34 dex when [ Fe/H ] < -2.5 .
Since the u and v filters bracket the Balmer Jump at 3646 Å , we also find that the filter-set can be used to derive surface gravities .
We thus derive photometric metallicities and surface gravities for all stars down to a magnitude of g \sim 20 within \sim 75 arcminutes of Tucana II .
Photometric metallicity and surface gravity cuts remove nearly all foreground contamination .
By incorporating Gaia proper motions , we derive quantitative membership probabilities which recover all known members on the red giant branch of Tucana II .
Additionally , we identify multiple likely new members in the center of the system and candidate members several half-light radii from the center of the system .
Finally , we present a metallicity distribution function derived from the photometric metallicities of likely Tucana II members .
This result demonstrates the utility of wide-field imaging with the SkyMapper filter-set in studying UFDs , and in general , low surface brightness populations of metal-poor stars .
Upcoming work will clarify the membership status of several distant stars identified as candidate members of Tucana II .