Comparison of the H i spectrum of NGC 2997 from the GBT map (solid line) and from the GMRT+ATCA Hess et al. (2009) data (dashed line). Both spectra are integrated over the same area (0.24 deg ²) and have been sampled with the same channel spacing. It is clear that the two spectra agree within the noise except around 1200 km s ⁻¹ where the GBT has recovered more flux.