  We present ground-based observations of the transiting Neptune-mass planet Gl
436b obtained with the 3.5-meter telescope at Apache Point Observatory and
other supporting telescopes. Included in this is an observed transit in early
2005, over two years before the earliest reported transit detection. We have
compiled all available transit data to date and perform a uniform modeling
using the JKTEBOP code. We do not detect any transit timing variations of
amplitude greater than ~1 minute over the ~3.3 year baseline. We do however
find possible evidence for a self-consistent trend of increasing orbital
inclination, transit width, and transit depth, which supports the supposition
that Gl 436b is being perturbed by another planet of < 12 Earth Masses in a
non-resonant orbit.
