  We present three transits of GJ 1214b, observed as part of the Apache Point
Observatory Survey of Transit Lightcurves of Exoplanets (APOSTLE). We used
APOSTLE r-band lightcurves in conjunction with previously gathered data of GJ
1214b to re-derive system parameters. By using parameters such as transit
duration and ingress/egress length we are able to reduce the degeneracies
between parameters in the fitted transit model, which is a preferred condition
for Markov Chain Monte Carlo techniques typically used to quantify
uncertainties in measured parameters. The joint analysis of this
multi-wavelength dataset confirms earlier estimates of system parameters
including planetary orbital period, the planet-to-star radius ratio and stellar
density. We fit the photometric spectralenergy distribution of GJ 1214 to
derive stellar luminosity, which we then use to derive its absolute mass and
radius. From these derived stellar properties and previously published radial
velocity data we were able to refine estimates of the absolute parameters for
the planet GJ 1214b. Transit times derived from our study show no evidence for
strong transit timing variations. Some lightcurves we present show features
that we believe are due to stellar activity. During the first night we observed
a rise in the out-of-eclipse flux of GJ 1214 with a characteristic fast-rise
exponential decay shape commonly associated with stellar flares. On the second
night we observed a minor brightening during transit, which we believe might
have been caused by the planet obscuring a star-spot on the stellar disk.
