The brightest pure-H ultracool white dwarf S. Catalán, P.-E. Tremblay, D. J. Pinfield, L. C. Smith, Z. H. Zhang, R. Napiwotzki, F. Marocco, A. C. Day-Jones, J. Gomes, K. P. Forde et al. (2 more) A&A, 546 (2012) L3 Published online: 01 October 2012 DOI: 10.1051/0004-6361/201220191