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).