We use deep Gemini/GMOS-S g,r photometry to study the three ultra-faint dwarf galaxy candidates DES1 , Eridanus III ( Eri III ) and Tucana V ( Tuc V ) .
Their total luminosities , M _ { V } ( DES1 ) = -1.42 \pm 0.50 and M _ { V } ( Eri III ) = -2.07 \pm 0.50 , and mean metallicities , [ Fe/H ] = -2.38 ^ { +0.21 } _ { -0.19 } and [ Fe/H ] = -2.40 ^ { +0.19 } _ { -0.12 } , are consistent with them being ultra-faint dwarf galaxies as they fall just outside the 1-sigma confidence band of the luminosity-metallicity relation for Milky Way satellite galaxies .
However , their positions in the size-luminosity relation suggests that they are star clusters .
Interestingly , DES1 and Eri III are at relatively large Galactocentric distances with DES1 located at D _ { GC } = 74 \pm 4 kpc and Eri III at D _ { GC } = 91 \pm 4 kpc .
In projection both objects are in the tail of gaseous filaments trailing the Magellanic Clouds and have similar 3D-separations from the Small Magellanic Cloud ( SMC ) : \Delta D _ { SMC,DES 1 } = 31.7 kpc and \Delta D _ { SMC,Eri III } = 41.0 kpc , respectively .
It is plausible that these stellar systems are metal-poor SMC satellites .
Tuc V represents an interesting phenomenon in its own right .
Our deep photometry at the nominal position of Tuc V reveals a low-level excess of stars at various locations across the GMOS field without a well-defined centre .
A SMC Northern Overdensity-like isochrone would be an adequate match to the Tuc V colour-magnitude diagram , and the proximity to the SMC ( 12 \fdg 1 ; \Delta D _ { SMC,Tuc V } = 13 kpc ) suggests that Tuc V is either a chance grouping of stars related to the SMC halo or a star cluster in an advanced stage of dissolution .