Setnam Shemar

Setnam Shemar works in the National Time Scale group of the Time and Frequency Department. He joined NPL in 1998 following a period in industry working as an analyst/software engineer. Prior to that he completed his B.Sc.(Hons) in Physics with astrophysics and postgraduate studies at the University of Manchester, the latter leading to a PhD in Radio Astronomy from Jodrell Bank Observatory in 1995 on timing studies of radio pulsars. Between 2002 and 2008 he was a Senior Scientist at QinetiQ in the Centre for propagation and atmospheric research, focusing on signal propagation in Galileo and GPS.

Setnam’s specialist area of research expertise is time and frequency transfer using satellite and other space-based techniques, in particular state-of-the-art methods for comparing national time scales and optical clocks over international and intercontinental distances. He is responsible for the UK’s contribution to ESA’s Atomic Clock Ensemble in Space (ACES) mission and is also the lead for developing time and frequency transfer methods for comparing clocks at distant sites in the National Timing Centre programme.

Setnam is a member of ESA’s ACES Investigator Working Group and the Positioning, Navigation and Timing (PNT) Technology Working Group within the Department for Science, Innovation and Technology. Between 2017 and 2019 he was a member of the Space Environments Working Group of the UK Space Agency.

Areas of interest

• Advanced time and frequency transfer techniques for comparing optical clocks over international and intercontinental distances by use of satellites
• Developing a resilient time scale infrastructure for the UK by building and linking a new atomic clock network distributed geographically in secure locations
• Mitigating the vulnerabilities of GNSS when used for timing in critical national infrastructure
• Use of space-based techniques to compare clocks globally for a redefinition of the second and tests of fundamental physics, and applications of the timing of pulsars
• Diversity and inclusion, in particular promoting an inclusive culture where staff from all ethnic backgrounds are supported and empowered (member of NPL’s Ethnicity group)

Key publications

• Direct comparisons of European primary and secondary frequency standards via satellite techniques
  F. Riedel, A. Al-Masoudi, E. Benkler, S. Dörscher, V. Gerginov, C. Grebing, S. Häfner, N. Huntemann, B. Lipphardt, C. Lisdat, E. Peik, D. Piester, C. Sanner, C. Tamm, S. Weyers, H. Denker, L. Timmen, C. Voigt, D. Calonico, G. Cerretto, G. A. Costanzo, F. Levi, I. Sesia, J. Achkar, J. Guéna, M. Abgrall, D. Rovera, B. Chupin, C. Shi, S. Bilicki, E. Bookjans, J. Lodewyck, R. Le Targat, P. Delva, S. Bize, F. N. Baynes, C. F. A. Baynham, W. Bowden, P. Gill, R. M. Godun, I. R. Hill, R. Hobson, J. M. Jones, S. A. King, P. B. R. Nisbet-Jones, A. Rolland, S. L. Shemar, P. B. Whibberley and H. S. Margolis
  Metrologia 57, 045005 (2020)
• Towards practical autonomous deep-space navigation using X-ray pulsar timing      S. Shemar, G. Fraser, L. Heil, D. Hindley, A. Martindale, P. Molyneux, J. Pye, R. Warwick, and A. Lamb
  Experimental Astronomy 42, 2, 101-138 (2016)
• PulChron: A pulsar time scale demonstration for PNT systems
  R. Píriz, E. Garbin, P. Roldán, M. Keith, B. Shaw, S. Shemar, K. Burrows, J. Davis,  S. Binda
  Proceedings of the 50th Annual Precise Time and Time Interval Systems and Applications Meeting, Reston, Virginia, January 2019, pp. 191-205
• Local representations of UTC in national laboratories
  P. B. Whibberley, J. A. Davis and S.L. Shemar
  Metrologia 48, S154-S164 (2011)

Setnam Shemar

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