A simulation calibrated limit on the HI power spectrum from the GMRT
  Epoch of Reionization experiment
  The GMRT Epoch of Reionization (EoR) experiment is an ongoing effort to
measure the power spectrum from neutral hydrogen at high redshift. We have
previously reported an upper limit of (70 mK)^2 at wavenumbers of k=0.65 h/Mpc
using a basic piecewise-linear foreground subtraction. In this paper we explore
the use of a singular value decomposition to remove foregrounds with fewer
assumptions about the foreground structure. Using this method we also quantify,
for the first time, the signal loss due to the foreground filter and present
new power spectra adjusted for this loss, providing a revised measurement of a
2-sigma upper limit at (248 mK)^2 for k=0.50 h/Mpc. While this revised limit is
larger than previously reported, we believe it to be more robust and still
represents the best current constraints on reionization at z=8.6.
