NEOWISE-R observation of the coolest known brown dwarf

The Wide-field Infrared Survey Explorer (WISE) spacecraft has been reactivated as NEOWISE-R to characterize and search for near-Earth objects. The brown dwarf WISE J085510.83-071442.5 has now been re-observed by NEOWISE-R, and we confirm the results of Luhman, who found a very low effective temperature (≈250 K), a very high proper motion (8.″1 ± 0.″1 yr^-1), and a large parallax (454 ± 45 mas). The large proper motion has separated the brown dwarf from the background sources that influenced the 2010 WISE data, allowing a measurement of a very red WISE color of W1 - W2 > 3.9 mag. A re-analysis of the 2010 WISE astrometry using only the W2 band, combined with the new NEOWISE-R 2014 position, gives an improved parallax of 448 ± 33 mas and a proper motion of 8.″08 ± 0.″05 yr^-1. These are all consistent with values from Luhman.