  We report the detection of an infrared selected transient which has lasted at
least 5 years, first identified by a large mid-infrared and optical outburst
from a faint X-ray source detected with the Chandra X-ray Observatory. In this
paper we rule out several scenarios for the cause of this outburst, including a
classical nova, a luminous red nova, AGN flaring, a stellar merger, and
intermediate luminosity optical transients, and interpret this transient as the
result of a Young Stellar Object (YSO) of at least solar mass accreting
material from the remains of the dusty envelope from which it formed, in
isolation from either a dense complex of cold gas or massive star formation.
This object does not fit neatly into other existing categories of large
outbursts of YSOs (FU Orionis types) which may be a result of the object's
mass, age, and environment. It is also possible that this object is a new type
of transient unrelated to YSOs.
