Colour magnitude diagrams of the candidate counterparts to 2XMM J174016.0−290337 and the surrounding field stars. The grey points are the field stars within 3′ of the X-ray source. The majority of this field population are Bulge giants forming the main concentration of points in the centre of each diagram, but there is also a small local dwarf population with lower colour values than the giant population. The 4 red circles represent the 4 candidate counterparts, with sources 2, 1 and 3 (from left to right respectively) all at approximately the same magnitude, and source 4 being the slightly fainter object in all three diagrams (see text and tables for details of the source numbering). The yellow points are the stars within 20″ of 2XMM J174016.0−290337 used for the extinction calculation and the light-blue square is the median value of these stars colours and magnitudes. The dark blue diamonds are main sequence standard stars taken from the UKIRT standard catalogue corrected for a distance modulus corresponding to 550 pc. These trace the observed local dwarfs in the field well and one of the candidate counterparts (source 2) has colours and magnitudes consistent with the latest M type dwarf. The green diamonds are giant standards also from the UKIRT standard catalogue corrected for a distance modulus corresponding to a distance of 8 kpc and with the measured extinction of 2.0 mag and 1.4 mag added to the H and K-bands respectively.