WISEPA J173835.53+273258.9 (abbreviated WISE 1738+2732) is a brown dwarf of spectral class Y0,[1][2] located in the constellation Hercules at 24.9 light-years from Earth.

[5] WISE 1738+2732 was discovered in 2011 from data, collected by the Wide-field Infrared Survey Explorer (WISE) Earth-orbiting satellite — NASA infrared-wavelength 40 cm (16 in) space telescope, which mission lasted from December 2009 to February 2011.

Disequilibrium chemistry models suggest that this Y-dwarf has a low mass of about 3-9 MJup, making it a possible isolated planetary-mass object, together with WISE 0350-5658.

It has a rotation period of 6.0±0.1 hours and the amplitude is 3% for 4.5 μm and may be as high as 5-30% in the near-infrared.

This dependence on wavelength can be reproduced with patchy cloud layers made up of potassium chloride (KCl) and sodium sulfide (Na2S).