A new two channel high-speed photo-polarimeter (HIPPO) for the SAAO

Potter, Stephen; Buckley, David; O'Donoghue, Darragh; James, O'Conner; Fourie, Piet; Evans, Geoff; Sass, Craig; Crause, Lisa; Butters, Olly; Norton, Andrew and Still, Martin (2008). A new two channel high-speed photo-polarimeter (HIPPO) for the SAAO. In: Proceedings of SPIE: Ground-based and Airborne Instrumentation for Astronomy II, 23 Jun 2008, Marseille, France, 70145E.

DOI: https://doi.org/10.1117/12.789716

Abstract

We report on the completion of a new 2 channel, HIgh speed Photo-POlarimeter (HIPPO) for the 1.9m optical telescope of the South African Astronomical Observatory. The instrument makes use of rapidly counter-rotating (10Hz), super-achromatic half- and quarter-waveplates, a fixed Glan-Thompson beamsplitter and two photo-multiplier tubes that record the modulated O and E beams. Each modulated beam permits an independent measurement of the polarisation and therefore simultaneous 2 filter observations. All Stokes parameters are recorded every 0.1sec and photometry every 1 millisecond. Post-binning of data is possible in order to improve the signal. This is ideal for measuring e.g. the rapid variability of the optical polarisation from magnetic Cataclysmic Variable stars. First light was obtained in February 2008.