Julien N. Girard

I am radio astronomer. I have been working as a post-doctoral researcher (LabEx UnivEarthS Frontier Project 3) at CEA Saclay from October 2013 to October 2015. I am specialized in low frequency radio interferomety (LOFAR) and (exo)planetary radio emissions.


I work with Jean-Luc Starck (AIM/LCS) and Stéphane Corbel (AIM/LEPCHE). 
I am member of the LOFAR Transient Key Project: "Planets & Exoplanets" and Co-I of the NenuFAR project (SKA pathfinder) in Nançay radio observatory.

I am now SKA Post-doctoral fellow of Rhodes University, Grahamstown, based at the SKA office in Cape Town (South Africa)


Contact information:

Phone: +33 (0)6 86 02 96 76 (France) / +27 (0) 79 703 1431 (South Africa) 

Email: jgirard (at) ska.ac.za ( alternative julien.girard (at) cea.fr or julien.girard (at) obspm.fr)

Address: SKA SA - 3rd Floor - The Park, Park Road - 7405 Pinelands


Research Interests

Sparse reconstruction of interferometric data

  • Application of Sparse theorems to LOFAR/SKA radio interferometry imaging
  • Development of a 3-D time-agile and multi-channel Sparse imager for the search of radio transients
  • Application to Weak lensing studies in preparation for the SKA

(Exo)planetary radio emissions at low frequencies

  • Jovian non-thermal emissions (radiobursts in the decameter range and radiation belts in the decimeter) with LOFAR
  • Abundance of water in Saturn deep atmosphere (kbar level) with LOFAR
  • Detection and study of Saturn Electrostatic Discharges (SED) with LOFAR
  • Search and characterization of exoplanetary transients radio signals with LOFAR

Preparation of NenuFAR/LSS (SKA pathfinder)

  • Instrumental design and simulation (array configuration, phasing)
  • Commissionning and data model and standardisation
  • Incremental development and scientific exploitation

Phased array interferometer optimization

  • Small antenna array beam optimization
  • Inteferometers/phased configurations
  • Graph theory approach for the Cable/Trench minimization problem (CTP)

Antenna design and Electromagnetic Simulations
Numerical Electromagnetic simulations (NEC) for ground-based instruments (LOFAR, NenuFAR) and space-borne instruments (Team member of the RPWI/JENRAGE on the JUICE/Laplace)

 

Education

I graduated from Magistère de Physique Fondamentale d'Orsay (Université Paris XI) and obtained a MSc in Astronomy & Astrophysics at Observatoire de Paris in 2009.

I defended my PhD in 2013 at Observatoire de Paris (LESIA) on the topic Development of the LOFAR Super Station and Planetary observations with LOFAR

I worked as a research scholar at Subaru Telescope (NAOJ & Research Corporation of the University of Hawaii, Hilo, HI) and intern at LESIA (Observatoire de Paris, Meudon)

My resume can be found at here.

Software

SASIR Sparse Aperture Synthesis Image Reconstruction (SASIR) available here.

Publications

Refereed Articles (Full list Here)

  • K. Zyma, J. N. Girard, E. Landquist, G. Schaper and F. J. Vasko, Formulating and solving a radio astronomy antenna connection problem as a generalized cable-trench problem: an empirical study, International Transactions in Operational Research, 1475-3995, 2016 Link
  • J. N. Girard, P. Zarka, C. Tasse, S. Hess, I. de Pater, D. Santos-Costa, Q. Nenon, A. Sicard, S. Bourdarie
    and 64 coauthors. Imaging Jupiter's radiation belts down to 127 MHz with LOFAR. A&A, 587:A3, March
    2016 ADS
  • J.N. Girard, H. Garsden, J.L. Starck, S. Corbel, A. Woiselle, C. Tasse, J.P. McKean and J. Bobin, Sparse representations and convex optimization as tools for LOFAR radio interferometric imaging, JINST, 2015, 10 C08013, doi:10.1088/1748-0221/10/08/C08013
  • Garsden H., Girard J. N., Starck J. L., Corbel S., Tasse C., Woiselle A., J. P. Mckean and xx others. LOFAR Sparse Image Reconstruction, Astron. Astrophys., 575, A90, 2015. Available here.
  • Zarka P., Bougeret J.-L., Briand C., Cecconi B., Falcke H., Girard J. N. et al., Planetary and exoplanetary low frequency radio observations from the Moon, Planet. Space Sci., Vol. 74, Issue 1, Pages 156-166, 2012.
  • Girard J. N., Zarka P., Tagger M. et al., Antenna design and distribution for a LOFAR Super Station, CR Physique Académie des Sciences, Volume 13, Issue 1, Pages 33-37, 2012.
  • Grießmeier J.-M., Zarka P., Girard J. N., Tagger M. et al., Observation of planetary radio emissions using large arrays, Radio Science, Volume 46, RS0F09, 9 PP., 2011.

In preparation

  • Girard J. N., Tasse C., Hess S., Zarka P., et al., Jupiter synchrotron radiation observed with LOFAR, Astron. & Astroph.
  • Girard J. N., Zarka P., Optimization of a small irregular 2D phased array layout synthesizing a wide-beam antenna pattern, Astron. & Astroph.
  • Zarka P., Tagger M., Denis L., Girard J. N., et al. NenuFAR: the LOFAR Super Station, Astron. & Astroph.

Conference Proceedings

  • M. Jiang, J. N. Girard, J. L. Starck, S. Corbel, and C. Tasse. Compressed sensing and radio interferometry.
    In Signal Processing Conference (EUSIPCO), 2015 23rd European, pages 1646-1650, August 2015 IEEE
  • M. Jiang, J. N. Girard, J.-L. Starck, S. Corbel, and C. Tasse. Interferometric Radio Transient Reconstruction
    in Compressed Sensing Framework. In F. Martins, S. Boissier, V. Buat, L. Cambresy, and P. Petit, editors,
    SF2A-2015: Proceedings of the Annual meeting of the French Society of Astronomy and Astrophysics. Eds.:
    F. Martins, S. Boissier, V. Buat, L. Cambresy, P. Petit, pp.231-236, pages 231-236, December 2015 (ADS)
  • J. N. Girard, P. Zarka, C. Tasse, and S. Hess, Jupiter synchrotron imaging with LOFAR, SF2A-2012 : Proc. Annual meeting of the French Society of Astronomy and Astrophysics, Eds. : S. Boissier, P. de Laverny, N. Nardetto, R. Samadi, D. Valls-Gabaud and H. Wozniak, Nice, France, pp.681-686, 2012
  • P., Zarka, J. N., Girard, M. Tagger, L. Denis, and the LSS team, LSS/NenuFAR : The LOFAR Super Station project in Nançay, SF2A-2012 : Proc. Annual meeting of the French Society of Astronomy and Astrophysics, Eds. : S. Boissier, P. de Laverny, N. Nardetto, R. Samadi, D. Valls-Gabaud and H. Wozniak, Nice, France, pp.687-694, 2012
  • Girard J. N., Zarka P., Tagger M., et al., Antenna Design and Distribution for a LOFAR Super Station in Nançay, in "Planetary Radio Emissions VII", H. O. Rucker et al. eds., Austrian Acad. Sci. Press, Vienna, Austria, p. 495-503, 2011 (refereed)
  • Zarka P., Girard, J. N., J.-M. Grießmeier, et al., Planetary and exoplanetary studies with the giant radio telescope LOFAR, in "Planetary Radio Emissions VII", H. O. Rucker et al. eds., Austrian Acad. Sci. Press, Vienna, Austria, p. 505, 2011 (refereed)
  • J.-M. Grießmeier, P. Zarka, A. Konovalenko, G. Fischer, V. Zakharenko, B. W. Stappers, J. N. Girard, B. Ryabov, D. Vavriv, V. Ryabov, and H. O. Rucker, Ground-based study of Saturn lightning, in "Planetary Radio Emissions VII", H. O. Rucker et al. eds., Austrian Acad. Sci. Press, Vienna, Austria, pp. 145-154, 2011 (refereed)
  • Grießmeier, J.-M., Zarka, P., Girard, J. N., Ter Veen, S. ,Falcke, H., Ground-based study of solar system planetary lightning, in proceedings of 3rd International SKA Forum 2010", PoS(ISKAF2010)022, 2010
  • P. Zarka, J.-M. Grießmeier, J. N. Girard, S. Hess, B. Cecconi, L. Denis, et al., Etudes Planetaires et Exoplanetaires avec le Radiotelescope LOFAR, Programme National de Planetologie, Colloque Quadriennal de Bilan et Prospective, IUEM Plouzané, France, 13-15-9-2010

Contributions to conference/workshops

Conferences (full list here)

  • July 2010: XLth YERAC - Young European Radio Astronomers Conference, Alcala de Henares, Espagne (talk)
  • September 2010: 7th International Workshop on Planetary, Solar and Heliospheric Radio Emissions, Graz, Autriche (poster)
  • December 2010: 1st France-Ukraine PICS program meeting (LOC/SOC), Meudon, France (talk)
  • March 2011: Journées scienti ques de l'URSI-France, Les radiotélescopes du futur : technologies et avancées scientifiques, Paris, France (URSI-France award of the best student contribution) (talk)
  • September 2011: TKP first results with LOFAR, Dalfsen, The Netherlands (talk & poster)
  • December 2011: LOFAR TKP meeting, Meudon, France (talk)
  • December 2011: 2nd France-Ukraine PICS program meeting, Meudon, France (talk)
  • August 2011: URSI General Assembly, Istanbul, Turkey (poster)
  • March 2012: UK-Germany National Astronomy Meeting (NAM), Manchester, UK (poster)
  • June 2012: Journées de la Société Française d'Astronomie et d'Astrophysique, Nice, France (talk)
  • June 2013: Semaine de l'Astrophysique Française de la SF2A, Montpellier, France (talk)
  • June 2013: AOGS, Brisbane, Australia (invited talk)
  • July 2013: Magnetospheres of Outer Planets, Athens, Greece (talk)
  • January 2014: LOFAR TKP meeting, Amsterdam, the Netherlands (2 talks)
  • February 2014: SKA-LOFAR Radio Days, Paris, France (talk)
  • April 2014: EGU General Assembly, Vienne, Austria (invited talk)
  • July 2014: 2nd International Summer School on : INtelligent Signal Processing for FrontIEr Research and Industry (INFIERI 2014), Paris, France (lecture)
  • September 2014: EPSC, Cascais, Portugal (invited talk)
  • September 2014: Radio Weak Lensing, Manchester, UK (talk)
  • October 2014: From Gaia to Cosmos: observation and modelling, Florence, Italy (poster)
  • 2015 PhySIS kick-off meeting, Saclay, France (talk)
  • May 2015: Magnetospheres of Outer Planets, Atlanta, USA (invited talk)
  • November 2015: SKA Bursary conference, Stellenbosch, South Africa (poster)

Workshops

  • September 2009: Towards third generation calibration in radio astronomy - MCCT SKADS/MeqTrees Workshop, USN, Nançay, France
  • December 2009: 6th Pulsar busy week, ASTRON, Dwingeloo, The Netherlands
  • April 2010: Transient busy week, ASTRON, Dwingeloo, The Netherlands
  • October 2010: 2nd LOFAR Data Processing School, ASTRON, Dwingeloo, The Netherlands
  • December 2010: LOFAR Programming Tutorial, ASTRON, Dwingeloo, The Netherlands
  • Juillet 2011: LOFAR Programming Tutorial, ASTRON, Dwingeloo, The Netherlands
  • May 2012: Long Baselines busy week, MPIfRA, Bonn, Germany
  • March 2013: LOFAR Dalfsen II : Collaboration Science Workshop, Dalfsen, the Netherlands (talk)
  • January 2014: NenuFAR workshop : the science of NenuFAR, Paris, France (talk)
  • May 2014: 14th NRAO synthesis imaging workshop, Socorro, United States
  • December 2014: LOFAR Imaging busy week, Dwingeloo, the Netherlands
  • March 2015:Next-Generation Radio Interferometric Imaging for the SKA 2015, Delheim, South Africa (here)
  • March 2015: Joint NL-SA radio continuum workshop

Conference & School organisation

  • 2015: International Young Astronomer School, ED127, Sèvres, France
  • 2014: SKA-LOFAR radio days (SOC/LOC), Paris, France
  • 2014: NenuFAR workshop: the science of NenuFAR, Paris, France
  • 2011: 3rd LOFAR TKP meeting (LOC), Meudon, France
  • 2011: 2nd France-Ukraine PICS program meeting (SOC/LOC), Meudon, France
  • 2010: 1st France-Ukraine PICS program meeting (SOC/LOC), Meudon, France