Milky Way Red Dwarfs in the BoRG Survey; Galactic scale-height and the
  distribution of dwarfs stars in WFC3 imaging
  We present a tally of Milky Way late-type dwarf stars in 68 WFC3
pure-parallel fields (227 arcmin^2) from the Brightest of Reionizing Galaxies
(BoRG) survey for high-redshift galaxies. Using spectroscopically identified
M-dwarfs in two public surveys, the CANDELS and the ERS mosaics, we identify a
morphological selection criterion using the half-light radius (r50), a
near-infrared J-H, G-J color region where M-dwarfs are found, and a V-J
relation with M-dwarf subtype. We apply this morphological selection of stellar
objects, color-color selection of M-dwarfs and optical-near-infrared color
subtyping to compile a catalog of 274 M-dwarfs belonging to the disk of the
Milky Way with a limiting magnitude of m_F125W < 24.
  Based on the M-dwarfs statistics, we conclude that (a) the previously
identified North/South discrepancy in M-dwarf numbers persists in our sample;
there are more M-dwarfs in the Northern fields on average than in Southern
ones, (b) the Milky Way's single disk scale-height for M-dwarfs is 0.3-4 kpc,
depending on sub-type, (c) {\bf ERRATUM:} we present corrected coordinates
(AstroPy) and distances and find a constant $z_0$=600 pc for all types. (d) a
second component is visible in the vertical distribution, with a different,
much higher scale-height. We report the M-dwarf component of the Sagittarius
stream in one of our fields with 11 confirmed M-dwarfs, 7 of which are at the
stream's distance.
  The dwarf scale-height and the relative low incidence in our fields of L- and
T-dwarfs in these fields makes it unlikely that these stars will be interlopers
in great numbers in color-selected samples of high-redshift galaxies. The
relative ubiquity of M-dwarfs however will make them ideal tracers of Galactic
Halo substructure with EUCLID and reference stars for JWST observations.
