880 $\mu$m SMA polarization observations of the quasar 3C 286

Abstract

For decades, the bright radio quasar 3C 286 has been widely recognized as one of the most reliable polarization calibrators at centimeter wavelengths because of its unchanging polarization position angle and high polarization percentage. However, it has become clear in recent years that the polarization position angle of 3C 286 changes with increasing frequency, increasing from ~33$^{\circ}$ at $\lambda \gtrsim 3$ cm to ~38$^{\circ}$ at $\lambda \approx 1$ mm. With the advent of high-sensitivity polarization observations by current and future (sub)millimeter telescopes, knowledge of the position angle of 3C 286 at higher frequencies is critical for calibration. We report the first polarization observations of 3C 286 at submillimeter wavelengths, taken at 880 $\mu$m (340 GHz) with the Submillimeter Array. We find a polarization position angle and percentage of $37.4 \pm 1.5^{\circ}$ and $15.7 \pm 0.8$%, respectively, consistent with previous measurements at 1 mm.