HIPPO is SAAO’s newest (2008) high-speed photo-polarimeter. It is capable of high-speed, multi-filtered, simultaneous all-Stokes observations of point sources. Its high-speed capabilities make it especially ideal for investigating rapidly varying astronomical sources such as magnetic cataclysmic variables. HIPPO was designed and built in order to replace its highly successful but ageing single channel equivalent, namely the University of Cape Town (UCT) photo-polarimeter (Cropper 1985).
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.
First light was obtained in February 2008.
Current status & availability
HIPPO is open for general use on the 1.9m only. Potential applicants should contact the PI (Stephen Potter: sbp at saao dot ac dot za) if first time users or would like to collaborate.
The HIPPO control software runs on a Linux operating system with a real-time linux kernel patch in order to guarantee absolute and relative timing accuracies. On-the-fly preliminary data reduction produces live photometry and polarimetry light curves.
Offline Data reduction
A set of data reduction algorithms are available. The routines are written for unix based operating systems (Linux and MacOS) and are compiled (e.g. using a gcc compiler) and executed from the command line. The data reduction process in split into three sets of reduction routines written in C. The first set deal with splitting the raw data file(s) into more manageable files sorted by target name, filter and channel. The second set extracts the photometry and handles binning, sky-subtraction and co-adding. The third set extracts the polarisation and handles binning, sky-subtraction, co-adding and polarisation calculation.
Software and sample reduction instructions are currently available upon request (Stephen Potter: sbp at saao dot ac dot za).
Please email the PI (Stephen Potter: sbp at saao dot ac dot za) if you are aware of any publications that have made use of HIPPO observations that are not listed below.
Yudin, R. V.; Potter, S. B.; Townsend, L. J. 2017MNRAS.464.4325, First multicolour polarimetry of TeV γ-ray binary HESS J0632+057 close to periastron passage
Buckley, D. A. H.; Meintjes, P. J.; Potter, S. B.; Marsh, T. R.; Gänsicke, B. T. 2017NatAs…1E..2, Polarimetric evidence of a white dwarf pulsar in the binary system AR Scorpii
Pekeur, N. W.; Taylor, A. R.; Potter, S. B.; Kraan-Korteweg, R. C., 2016MNRAS.462L..80 Evidence for quasi-periodic oscillations in the optical polarization of the blazar PKS 2155-304
Potter, Stephen B., 2016ASSL..439..179 Stokes Imaging: Mapping the Accretion Region(s) in Magnetic Cataclysmic Variables
Potter, S.B. 2015AcPPP…2..139 High-Speed Photo-Polarimetry of Magnetic Cataclysmic Variables
Buckley, D. A. H.; Potter, S. B.; Kotze, E.; Kotze, M.; Breytenbach, H. 2014EPJWC..6407005 New Observations of Accretion Phenomena in Magnetic Cataclysmic Variables
Kniazev A. Y. et al. ApJ, 2013, 770, 124: Characterization of the nearby L/T Binary Brown Dwarf WISE J104915.57-531906.1 at 2 Pc from the Sun
Potter S. The fourth Gaia Science Alerts workshop, 2013: South African Astronomy and Observatories
Potter S. IAUS, 2012, 285, 117: Polarimetric Variability
Potter et al, MNRAS, 2012, 420, 2596: On the spin modulated circular polarization from the intermediate polars NY Lup and IGR J15094-6649
Potter S., LSST all hands meeting, 2012: Time Domain Science and LSST Follow-up in South Africa
Andersson B.-G.; Potter S. B. ASPC, 2011, 449, 134: Observational Evidence for Radiative Interstellar Grain Alignment
Potter S. et al, ASPC, 2011, 449, 27: First Science Results from the High Speed SAAO Photo-polarimeter
Potter S. et al, MNRAS, 2011, 416, 2202: Possible detection of two giant extrasolar planets orbiting the eclipsing polar UZ Fornacis
Revnivtsev M. et al. MNRAS, 2011, 411, 1317: Observational evidence for matter propagation in accretion flows
Russell D. et al. 2011,ArXiv1104, 837: Rapid variations of polarization in low-mass X-ray binaries
Russell D. et al. PoS, htra-IV, 2010: Rapid variations of polarization in low-mass X-ray binaries
Andersson B.-G.; Potter S. B. ApJ, 2010, 720, 1054: Observations of Enhanced Radiative Grain Alignment Near HD 97300
Andersson B.-G.; Potter S. B. AAS, 2010, 42, 320: Observations of Enhanced Radiative Grain Alignment Near HD 97300
Potter S. et al. MNRAS, 2010, 402, 1161: Polarized QPOs from the INTEGRAL polar IGRJ14536-5522 (=Swift J1453.4-5524) also describes HIPPO commissioning
Potter S. et al. SPIE, 2008, 7014, 179: A new two channel high-speed photo-polarimeter (HIPPO) for the SAAO