Siddhartha Pathak

C-BASS, MMICs, and KuBE: Cutting-Edge Instruments and Experiments

Where is he NOW? - It's a mystery... Let us know when you find him.

"The research I carried out while a Keck Institute Postdoctoral Fellow was focussed on two areas. The first was related to the polarized cosmic microwave background (CMB) - a signal from the dawn of the universe which may contain the clearest view yet of how our universe was born. My research was focussed on two aspects of this: a project to map the polarized emission from our Galaxy, which obscures our view of the polarized CMB, called C-BASS; and a project to improve the technology which is being used to directly measure the polarized CMB.

The second theme to my research has been studying relativistic jets in blazars. The relativistic jets which are thought to power blazars are a fascinating astrophysical mystery: in spite of five decades of intensive study we still do not know how relativistic jets are accelerated and collimated, nor what their composition is. We have entered a new era in the study of blazar jets with the launch of the Fermi gamma-ray space telescope. It is now possible, for the first time, to monitor the gamma-ray flux of a large number of blazars; this has sparked the advent of very powerful multi-wavelength flux monitoring campaigns from radio through to gamma-ray wavelengths. I built a radio polarimeter called KuPol for the 40m telescope at OVRO to monitor the linear polarization of over 1000 blazars, and lead an effort called RoboPol to build and use a polarimeter for a similar survey at optical wavelengths.

I am currently a Senior Scientist in the Astronomy department at Caltech. I am continuing my research in blazar jet emission using KuPol and RoboPol, and with the scientific analysis of the C-BASS data." (March 2012)


  1. “C-Band All-Sky Survey: a first look at the Galaxy”. M. O. Irfan, C. Dickinson, R. D. Davies, C. Copley, R. J. Davis, P. G. Ferreira, C. M. Holler, J. L. Jonas, Michael E. Jones, O. G. King, J. P. Leahy, J. Leech, E. M. Leitch, S. J. C. Muchovej, T. J. Pearson, M. W. Peel, A. C. S. Readhead, M. A. Stevenson, D. Sutton, Angela C. Taylor, J. Zuntz . Monthly Notices of the Royal Astronomical Society, 448, 3572-3586 (March 2015). DOI: 10.1093/mnras/stv212 — Preprint: arXiv:1501.06069
  2. “Astronomical receiver modelling using scattering matrices”. O. G. King, Michael E. Jones, C. Copley, R. J. Davis, J. P. Leahy, J. Leech, S. J. C. Muchovej, T. J. Pearson, Angela C. Taylor 
    Monthly Notices of the Royal Astronomical Society, 446, 1252-1267 (January 2015) . DOI: 10.1093/mnras/stu2172 — Preprint: arXiv:1410.5469
  3. “The C-Band All-Sky Survey (C-BASS): Design and implementation of the northern receiver”. O. G. King, Michael E. Jones, E.J. Blackhurst, C. Copley, R.J. Davis, C. Dickinson, C. M. Holler, M. O. Irfan, J. J. John, J. P. Leahy, J. Leech, S. J. C. Muchovej, T. J. Pearson, M. A. Stevenson, Angela C. Taylor . Monthly Notices of the Royal Astronomical Society, 438, 2426-2439 (March 2014) 
    DOI: 10.1093/mnras/stt2359 — Preprint: arXiv:1310.7129
  4. “A Circularly Symmetric Antenna Design With High Polarization Purity and Low Spillover”. Holler, C. M., Taylor, A. C., Jones, M. E., King, O. G., Muchovej, S. J. C., Stevenson, M. A., Wylde, R. J., Copley, C. J., Davis, R. J., Pearson, T. J., Readhead, A. C. S.  IEEE Transactions on Antennas and Propagation, 61, 117 (January 2013) . DOI: 10.1109/TAP.2012.2219843 — Preprint: arXiv:1111.2702
  5. "Blazars in the Fermi Era: The Ovro 40 m Telescope Monitoring Program", J. L. Richards, W. Max-Moerbeck, V. Pavlidou, O. G. King, et al.The Astrophysical Journal Supplement Series, 194:29 (22pp), 2011. doi:10.1088/0067-0049/194/2/29. June, 2011. (pdf)
  6. “The C-Band All-Sky Survey: instrument design, status, and first-look data”. Oliver G. King, Charles Copley, Rod Davies, Richard Davis, Clive Dickinson, Yaser A. Hafez, Christian Holler, Jaya John John, Justin L. Jonas, Michael E. Jones, J. Patrick Leahy, Stephen J. C. Muchovej, Timothy J. Pearson, Anthony C. S. Readhead, Matthew A. Stevenson, Angela C. Taylor . Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V. Edited by Holland, Wayne S.; Zmuidzinas, Jonas. Proceedings of the SPIE, Volume 7741, pp. 77411I-77411I-10 (2010). Jul 2010 . ADS: 2010SPIE.7741E..42K — DOI: 10.1117/12.858011 — Preprint: arXiv:1008.4082
  7. “Compact broadband planar orthomode transducer”. Grimes, P. K., King, O. G., Yassin, G., Jones, M. E.  Electronics Letters, 43(21), pp. 1146-1148 (October 2007). DOI: 10.1049/el:20071649 — Preprint: arXiv:0709.1777