  AA Tau is a well studied young stellar object that presents many of the
photometric characteristics of a Classical T Tauri star (CTTS), including
short-timescale stochastic variability attributed to spots and/or accretion as
well as long duration dimming events attributed to occultations by vertical
features (e.g., warps) in its circumstellar disk. We present new photometric
observations of AA Tau from the Kilodegree Extremely Little Telescope North
(KELT-North) which reveal a deep, extended dimming event in 2011, which we show
supports the interpretation by Bouvier et al. (2013) of an occultation by a
high-density feature in the circumstellar disk located >8 AU from the star. We
also present KELT-North observations of V409 Tau, a relatively unstudied young
stellar object also in Taurus-Auriga, showing short timescale erratic
variability, along with two separate long and deep dimming events, one from
January 2009 through late October 2010, and the other from March 2012 until at
least September 2013. We interpret both dimming events to have lasted more than
600 days, each with a depth of ~1.4 mag. From a spectral energy distribution
analysis, we propose that V409 Tau is most likely surrounded by a circumstellar
disk viewed nearly edge-on, and using Keplerian timescale arguments we
interpret the deep dimmings of V409 Tau as occultations from one or more
features within this disk >10 AU from the star. In both AA Tau and V409 Tau,
the usual CTTS short-timescale variations associated with accretion processes
close to the stars continue during the occultations, further supporting the
distant occulting material interpretation. Like AA Tau, V409 Tau serves as a
laboratory for studying the detailed structure of the protoplanetary
environments of T Tauri disks, specifically disk structures that may be
signposts of planet formation at many AU out in the disk.
