  Through the Backyard Worlds: Planet 9 citizen science project we discovered a
late-type L dwarf co-moving with the young K0 star BD+60 1417 at a projected
separation of 37" or 1662 AU. The secondary - CWISER J124332.12+600126.2
(W1243) - is detected in both the CatWISE2020 and 2MASS reject tables. The
photometric distance and CatWISE proper motion both match that of the primary
within ~1sigma and our estimates for chance alignment yield a zero probability.
Follow-up near infrared spectroscopy reveals W1243 to be a very red 2MASS
color(J-Ks=2.72), low-surface gravity source that we classify as L6 - L8gamma.
Its spectral morphology strongly resembles that of confirmed late-type L dwarfs
in 10 - 150 Myr moving groups as well as that of planetary mass companions. The
position on near- and mid-infrared color-magnitude diagrams indicates the
source is redder and fainter than the field sequence, a telltale sign of an
object with thick clouds and a complex atmosphere. For the primary we obtained
new optical spectroscopy and analyzed all available literature information for
youth indicators. We conclude that the Li I abundance, its loci on
color-magnitude and color-color diagrams, and the rotation rate revealed in
multiple TESS sectors are all consistent with an age of 50 - 150 Myr. Using our
re-evaluated age of the primary, the Gaia parallax along with the photometry
and spectrum for W1243 we find a Teff=1303+/-31 K, logg=4.3+/-0.17 cm s-2, and
a mass of 15+/-5 MJup. We find a physical separation of ~1662 AU and a mass
ratio of ~0.01 for this system. Placing it in context with the diverse
collection of binary stars, brown dwarf and planetary companions, the BD+60
1417 system falls in a sparsely sampled area where the formation pathway is
difficult to assess.
