tokens: for excision of data affected by radio frequency interference. After the initial data editing, and gain and bandpass calibration using observations of the compact source 0204+152, a standard self-calibration procedure was carried out for each target source, using line-free channels. The imaging was done with the task tclean , with the w-projection algorithm (Cornwell et al. 2008 ). In the case of J0229+0053, where the observing bandwidth was large, we additionally used the MT-MFS algorithm (second-order expansion; Rau Cornwell 2011 ) to image the target field. The synthesized beams of the final continuum images have full widths at half maximum (FWHMs) of (J0229+0044) and (J0229 + 0053). Both sources were found to be unresolved in our continuum images, with flux densities of mJy (J0229+0044, at ≈640 MHz) and mJy (J0229+0053, at ≈657 MHz). The quoted errors include the error measured from a two-dimensional Gaussian fit to a small region around each source and the typical error in the GMRT flux density scale, ≈10% at these frequencies. The task uvsub was then used to subtract out all detected continuum emission from the self-calibrated visibilities of each field. For each source, a spectral cube was made from these continuum-subtracted visibilities in the barycentric frame, using natural weighting. The H i 21 cm spectrum was extracted by taking a cut through the cube at the AGN location. The final spectrum for each source was then obtained by fitting a second-order polynomial to the line-free regions of each spectrum, and subtracting this out. We further smoothed the spectra by seven channels (J0229+0044) and two channels (J0229+0053), to velocity resolutions of ≈26.6 km s −1 and ≈11.2 km s −1 , respectively. The final optical depth rms noise values are ≈0.12 per 26.6 km s −1 (J0229+0044) and 0.0068 per 11.2 km s −1 (J0229+0053). Our final H i 21 cm spectra toward J0229+0044 and J0229+0053 are shown in Figures 1 (left) and (right), respectively. The velocity-integrated H i 21 cm optical depths are km s −1 (J0229+0044) and km s −1 (J0229+0053). Assuming K and a covering factor, f = 1, these integrated H i 21 cm optical depths imply H i column densities of N hi = (1.35 ± 0.14) × ( T s /100) × 10 22 cm −2 (J0229+0044) and N hi = (1.429 ± 0.015) × ( T s /100) ×10 22 cm −2 (J0229+0053). Note that these are conservative assumptions: a lower covering factor or a higher spin temperature would imply even higher H i column densities. The observational results are summarized in Table 1 . Figure 1. The H i 21 cm spectra toward (left) J0229+0044 and (right) J0229+0053, at velocity resolutions of ≈26.6 km s −1 and ≈11.2 km s −1 , respectively. The solid horizontal line in each panel indicates the AGN continuum flux density at the redshifted H i 21 cm line frequency. The 1 σ rms noise values on the spectra (the horizontal dashed lines) are 0.41 mJy per ≈26.6 km s −1 (J0229+0044) and 0.29 mJy per ≈11.2 km s −1 (J0229+0053). The velocity axes in both panels are
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