Improved Infrared Photometry and a Preliminary Parallax Measurement for the Extremely Cold Brown Dwarf CWISEP J144606.62-231717.8

We present follow-up Spitzer observations at 3.6 μm (ch1) and 4.5 μm (ch2) of CWISEP J144606.62-231717.8, one of the coldest known brown dwarfs in the solar neighborhood. This object was found by mining the Wide-field Infrared Survey Explorer (WISE) and NEOWISE data via the CatWISE Preliminary Catalog by Meisner et al., where an initial Spitzer color of ch1-ch2 = 3.71 ± 0.44 mag was reported, implying it could be one of the reddest, and hence coldest, known brown dwarfs. Additional Spitzer data presented here allows us to revise its color to ch1-ch2 = 2.986 ± 0.048 mag, which makes CWISEP J144606.62-231717.8 the fifth reddest brown dwarf ever observed. A preliminary trigonometric parallax measurement, based on a combination of WISE and Spitzer astrometry, places this object at a distance of {10.1}_-1.3^+1.7 pc. Based on our improved Spitzer color and preliminary parallax, CWISEP J144606.62-231717.8 has a T _eff in the 310-360 K range. Assuming an age of 0.5-13 Gyr, this corresponds to a mass between 2 and 20 M _Jup.