Spitzer follow-up of Y brown dwarfs

CatWISE, a joint analysis of archival WISE and NEOWISE data, has improved upon the motion measurements of AllWISE by leveraging a >10x time baseline enhancement, from 0.5yr (AllWISE) to 6.5yr (CatWISE). As a result, CatWISE motion selection has yielded a large sample of previously unrecognized brown dwarf candidates, many of which have archival detections exclusively in the WISE 4.6{mu}m (W2) channel, suggesting that they could be both exceptionally cold and nearby.

Where these objects go undetected in WISE W1 (3.4{mu}m), Spitzer can provide critically informative detections at 3.6{mu}m. Of our motion-confirmed discoveries, 17 have a best-fit Spitzer [3.6]-[4.5] color most consistent with spectral type Y. It is likely that CWISEP J144606.62-231717.8 ({mu}~1.3yr^-1^) is the reddest, and therefore potentially coldest, member of our sample with a very uncertain [3.6]-[4.5] color of 3.71+/-0.44mag.