Context : The optical counterpart of the neutron star X-ray binary and well known X-ray burster , 4U 1636–53 ( = 4U 1636–536 = V801 Ara ) has been well studied for three decades .
However to date , no infrared studies have been reported .

Aims : Our aims are to identify and investigate the near-infrared ( NIR ) counterpart of 4U 1636–53 .

Methods : We present deep , K _ { S } -band ( 2.2 \mu \mathrm { m } ) imaging of the region of 4U 1636–53 taken with the Infrared Spectrometer And Array Camera ( ISAAC ) on the Very Large Telescope .
Archival optical and UV data are used to infer the 0.2 - 2.2 \mu \mathrm { m } spectral energy distribution ( SED ) .

Results : One star is located at coordinates \alpha = 16 :40:55.57 , \delta = -53 :45:05.2 ( J2000 ; 1 \sigma positional uncertainty of \sim 0.3 arcsec ) which is consistent with the known optical position of 4U 1636–53 ; its magnitude is K _ { S } = 16.14 \pm 0.12 .
This star is also detected in the 2MASS survey in J -band and has a magnitude of J = 16.65 \pm 0.22 .
Under the assumption that the persistent emission is largely unvarying , the 0.4 - 2.2 \mu \mathrm { m } de-reddened SED can be described by a power law ; F _ { \nu } \propto \nu ^ { 1.5 \pm 0.3 } , with some possible curvature ( F _ { \nu } \propto \nu ^ { \lesssim 1.5 } ) at 0.2 - 0.4 \mu \mathrm { m } .
The SED can be approximated by a blackbody of temperature \sim 27000 K. This is typical for an active low-mass X-ray binary , and the emission can be explained by the outer regions of a ( likely irradiated ) accretion disc .
We therefore interpret this K _ { S } -band star as the NIR counterpart .

Conclusions :