The challenges of low-frequency radio polarimetry: Lessons from the Murchison widefield array by Lenc, E, Anderson, CS, Barry, N, Bowman, JD, Cairns, IH, Farnes, JS, Gaensler, BM, Heald, G, Johnston-Hollitt, M, Kaplan, DL, Lynch, CR, McCauley, PI, Mitchell, DA, Morgan, J, Morales, MF, Murphy, T, Offringa, AR, Ord, SM, Pindor, B, Riseley, C, Sadler, EM, Sobey, C, Sokolowski, M, Sullivan, IS, O’Sullivan, SP, Sun, XH, Tremblay, SE, Trott, CM, Wayth, RB