Two very nearby (d ~ 5 pc) ultracool brown dwarfs detected by their
  large proper motions from WISE, 2MASS, and SDSS data
  Aims: WISE provides an infrared all-sky survey which aims at completing our
knowledge on the possibly dramatically increasing number of brown dwarfs with
lower temperatures. We search for the nearest representatives of the coolest
brown dwarfs, which will be very interesting for detailed follow-up
observations, once they haven been discovered. Methods: We have used the
preliminary data release from WISE, selected bright candidates with colours
typical of late-T dwarfs, tried to match them with faint 2MASS and SDSS
objects, to determine their proper motions, and to follow-up them
spectroscopically. Results: We have identified two new ultracool brown dwarfs,
WISE J0254+0223 and WISE J1741+2553, with large proper motions of about 2.5 and
1.5 arcsec/yr, respectively. With their w1-w2~3.0 and J-w2~4.0 colour indices
we expect both to have a spectral type of ~T8-T10 and absolute magnitude of
M_{w2}~14. We confirm WISE J1741+2553 as a T9-T10 dwarf from near-infrared
spectroscopy with LBT/LUCIFER1. From their bright WISE w2 magnitudes of 12.7
and 12.3, we estimate distances of 5.5$^{+2.3}_{-1.6}$ pc and
4.6$^{+1.2}_{-1.0}$ pc and tangential velocities of ~65 km/s and ~34 km/s
indicating Galactic thick and thin disk membership, respectively.
