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Tremaine and Weinberg (TW) proposed a conceptually simple procedure relyingon long-slit spectroscopy to measure the pattern speeds of bars ($\Omega_{\rmp}$) in disk galaxies. Using a simulated galaxy, we investigate the potentialbiases and uncertainties of TW measurements using increasingly popularintegral-field spectrographs (IFSs), for which multiple pseudo-slits (and thusindependent measurements) can be constructed with a single observation. Mostimportant, to establish the spatial coverage required and ensure the validityof the measurements, the inferred $\Omega_{\rm p}$ must asymptotically convergeas the (half-)length of each pseudo-slit used is increased. The requirement forour simulation is to reach $\approx1.3$ times the half-light radius, but thismay vary from galaxy to galaxy. Only those slits located within the bar regionyield accurate measurements. We confirm that the position angle of the disk isthe dominant source of systematic error in TW $\Omega_{\rm p}$ measurements,leading to under/overestimates of tens of percents for inaccuracies of even afew degrees. Recasting the data so that the data grid aligns with the diskmajor axis leads to slightly reduced uncertainties. Accurate measurements areobtained only for well-defined ranges of the bar angle (relative to the galaxymajor axis) $\phi_{\rm bar}$ and the inclination angle $i$, here$10\lesssim\phi_{\rm bar}\lesssim75^{\circ}$ and $105\lesssim\phi_{\rmbar}\lesssim170^{\circ}$ and $15\lesssim i\lesssim70^{\circ}$. The adopted(pseudo-)slit widths, spatial resolution, and (unless extremely aggressive)spatial binning of IFS data have no significant impact on the measurements. Ourresults thus provide useful guidelines for reliable and accurate direct$\Omega_{\rm p}$ measurements with IFS observations.

Testing the Tremaine-Weinberg Method Applied to Integral-field Spectroscopic Data Using a Simulated Barred Galaxy