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ST14-A004 (Invited), AOGS 2011 – Taipei, Taiwan – 11 August 2011

ST14-A004 (Invited), AOGS 2011 – Taipei, Taiwan – 11 August 2011. Past, Present, and Future Radio Heliospheric Remote-Sensing Studies Using the EISCAT, ESR, MERLIN, LOFAR, and EISCAT-3D Radio Systems.

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ST14-A004 (Invited), AOGS 2011 – Taipei, Taiwan – 11 August 2011

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  1. ST14-A004 (Invited), AOGS 2011 – Taipei, Taiwan – 11 August 2011 Past, Present, and Future Radio Heliospheric Remote-Sensing Studies Using the EISCAT, ESR, MERLIN, LOFAR, and EISCAT-3D Radio Systems. Mario M. Bisi1,2(Mario.Bisi@aber.ac.uk), Richard A. Fallows2, Andrew R. Breen2, Periasamy K. Manoharan3, Elizabeth A. Jensen4, Stuart Hardwick2, Bernard V. Jackson1, and John M. Clover1. 1Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Drive #0424, La Jolla, CA 92093-0424, USA. 2Institute of Mathematics and Physics, Aberystwyth University, Penglais Campus, Aberystwyth, SY23 3BZ, Wales, UK. 3Radio Astronomy Centre, National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Udhagamandalam (Ooty), 643 001, India. 4Planetary Sciences Institute, 1700 East Fort Lowell, Suite 106. Tucson, AZ 85719-2395, USA.

  2. Outline • The Multi-Site IPS Experiment • Present and Future IPS Telescopes/Arrays in this Talk • Highlights of Past works with EISCAT/ESR and MERLIN by Aberystwyth University and those in close collaboration with the University of California, San Diego • IPS with LOFAR: Initial Test Observations and Results • Overall Summary and Future Prospects

  3. Multi-Site IPS (1) Radio signals received at each site are very similar except for a small time-lag.The cross-correlation function can be used to infer the solar wind velocity(s) across the line of sight (LOS). (Not to scale) Hubble Deep Field – HST (WFPC2) 15/01/96 – Courtesy of R. Williams and the HDF Team and NASA IPS is most-sensitive at and around the P-Point of the LOS to the Sun and is only sensitive to the component of flow that is perpendicular to the LOS; it is variation in intensity of astronomical radio sources on timescales of ~0.1s to ~10s that is observed.

  4. Multi-Site IPS (2)

  5. IPS Arrays/Telescopes (1) Above: The European Incoherent SCATter radar (EISCAT) and EISCAT Svalbard Radar (ESR) radio telescopes from left-to-right: Tromsø, Norway (M.M. Bisi, October 2003); Kiruna, Sweden (M.M. Bisi, May 2003); Sodankylä, Finland (http://www.eiscat.com/sodan.html); and the ESR 42m in the foreground and steerable 32m in the background (M.M. Bisi, May 2005). Left: The Multi-Element Radio-Linked Interferometer Network (MERLIN) MkIa (Lovell) radio telescope at Jodrell Bank (near Manchester, England); and Right: The MERLIN MkII radio telescope also at Jodrell Bank (M.M. Bisi, May 2004).

  6. IPS Arrays/Telescopes (2) LOFAR Core High-Band Antenna (top) and LOFAR Core Low-Band Antenna (bottom); both with Richard Fallows (~ 5’ 5½” tall) in for size comparison. LOFAR superterp (top) and LOFAR Chilbolton (bottom).

  7. Array of radio telescopes. • Centred in the Netherlands. • International stations extending from the UK to Ukraine. The LOw Frequency ARray (LOFAR) The Netherlands core stations contain 48 dipoles per array and the International stations 96 dipoles per array: overall band width up to 48 MHz.

  8. LOFAR Summary • Frequency agile system over two primary bands with observing capabilities of 10 MHz to 250 MHz split into 10 MHz to 90 MHz and 110 MHz to 250 MHz with two antenna types. • Ample collecting area with plenty of combinations of multi-site observations with the International Stations. • Should be able to match Ootacamund (Ooty) Radio Telescope’s number of source-observations per day, and also exceed 50 two-site observations per day (depending on station availability). • Possibilities of ~5° angular resolution in three-dimensional (3-D) tomographic reconstructions look achievable with LOFAR data. • The Murchison Widefield Array (MWA) in Western Australia could match (or possibly exceed) the number of source-observations per day, but it won’t offer simultaneous two-/multi-site observations of the same radio source on the sky.

  9. Highlights of Past works with EISCAT/ESR and MERLIN by Aberystwyth University and those in close collaboration with the University of California, San Diego

  10. Summary of Selected Publications • Extremely-Long Baseline IPS Experiment – e.g. Bisi et al., ESA, 2005; Bisi, Ph.D. Thesis, 2006; Breen et al., JGR, 2006; Jones et al., Ann. Geophys., 2006; Fallows et al., A&A Trans., 2007. • Non-radial Flow of the Solar Wind – e.g.Moran, Ph.D. Thesis, 1998; Moran et al., Ann. Geophys., 1998; Bisi, Ph.D. Thesis, 2006; Breen et al., Ap.J.Lett., 2008. • Dual-Frequency IPS Experiment – e.g.Fallows et al., GRL, 2006; Bisi, Ph.D. Thesis, 2006; Fallows et al., A. and A. Trans., 2007. • EISCAT 3-D C.A.T. Reconstruction – e.g.Bisi et al.,SPIE, 2007; Bisi et al., Sol. Phys., 2010. • Possible Bi-Modal Structure of the Fast Solar Wind – Bisi et al., JGR, 2007. • Advances in Weak-Scattering IPS Analyses with EISCAT – e.g.Fallows, Ph.D. Thesis, 2001; Fallows et al., Ann. Geophys., 2009.

  11. 2007/04/20-2007/05/20 Co-rotating solar-wind velocities (around the declining phase to solar minimum) – EISCAT IPS data - Bisi, M.M., B.V. Jackson, A.R. Breen, G.D. Dorrian, R.A. Fallows, J.M. Clover, and P.P. Hick, “Three-Dimensional (3-D) Reconstructions of EISCAT IPS Velocity Data in the Declining Phase of Solar Cycle 23”, Solar Physics “Remote Sensing of the Inner Heliosphere” Topical Issue (Guest Editors M.M. Bisi and A.R. Breen), 265 (1-2), pp.233-244, doi:10.1007/s11207-010-9594-4, 2010.

  12. EISCAT IPS 3-D Velocity Reconstruction

  13. IPS with LOFAR: Initial Test Observations and Results

  14. LOFAR (Select) Initial Observations of IPS: Overview • Single core station observations of source J1229+020 (3C273) took place on 30 October 2010 – used both a core LOFAR High-Band Antenna (HBA) and a core LOFAR Low-Band Antenna (LBA) at a sampling rate of 96 Hz: HBA – 160 MHz with a 14 MHz band width – 07:40UT-07:55UT;LBA – 64 MHz with a 14 MHz band width – 08:00UT-08:15UT. • Observations of J0137+331 (3C48) with the Superterp on 09 April 2011 using the highest range of HBA over a 40 MHz band width centred on 230 MHz – 11:00UT-11:30UT. • Observations again using Superterp as above in April 2011, but this time of source J0319+415 (3C84) on 07 May 2011 – 14:00UT-14:30UT (joint with the ESR); and ESR with EISCAT Sodankylä (earlier in the day for context) – 08:45UT-09:15UT.

  15. Quick Guide to the IPS Power Spectrum • An example power spectrum from an observation of IPS with its key features marked.

  16. LOFAR (Select)Initial Observations of IPS (1) • Dynamic spectra (top-left with RFI left in, bottom-left with RFI taken out), raw time series (top right), and LOFAR IPS spectrum comparison with Ooty IPS (bottom right). • J1229+020 (3C273): RFI still causing some issues here.

  17. LOFAR (Select)Initial Observations of IPS (2) • 09 April 2011. • Remove the RFI-contaminated channels by averaging over them in the frequency dimension. • Flatten the data by dividing each channel by its median. • Sum over the band width to create RFI-removed raw time series. • J0137+331 (3C48): RFI removal seems more effective this time.

  18. J0137+331 (3C48) Original Processed LOFAR (Select) Initial Observations of IPS (3) • RFI-removed (bottom left) time series looks like IPS should look with noticeable changes from the non-RFI-removed (top left). • The spectrum (right) also looks like IPS with the Fresnel knee marked by the vertical dashed red line roughly where expected.

  19. LOFAR ESR LOFAR (Select) Initial Observations of IPS (4) • Observation of IPS using 0319+415 (3C84). • The fully LOFAR Superterp cleaned-up data set. Notice how the “scintillation”(?) seems patch across frequency channels (top). • Comparison of LOFAR Superterp (230 MHz, 40 MHz band width) and ESR (500 MHz, 5.4 MHz band width) IPS time series (bottom). 07 May 2011

  20. LOFAR (Select) Initial Observations of IPS (5) • Comparison with ESR is encouraging, but possible LOFAR sensitivity issues: expect Superterp to have much greater sensitivity than ESR (may not be – only one observation though!).

  21. LOFAR (Select) Initial Observations of IPS (6) • 08:45UT: “Fresnel knee” about where expected and power laws appear the same for both frequencies; not great S/N from either of the sites. • 14:00UT yields an interesting comparison: “Fresnel knee” (turn-over point of spectrum) at very low frequency with differing power laws. The Superterp also appears slightly less sensitive than ESR!?

  22. LOFAR (Select) Initial Observations of IPS (7) • What happens if we split the wide band width of the LOFAR observation into something more like that of the ESR? We get more questions… • Comparison of ESR and MEXART (courtesy of J.C. Mejia-Ambriz and J.A. Gonzalez-Esparza) with LOFAR data split into two small band widths covering the “best” parts of the dynamic spectrum.

  23. Overall Summary and Future Prospects

  24. Low band LOFAR IPS (all latitudes) High band STEREO HI1 & HI2 (<30º of ecliptic) (Ooty also) SMEI (all latitudes) Observing Summary (not exclusive) Observations of IPS with the Murchison Widefield Array (MWA) will cover a similar range as LOFAR starting perhaps a little closer to the Sun, but not extending so far out from the Sun…

  25. IPS Summary and Future Prospects • There are many world-wide IPS-capable systems and IPS is a very powerful and unique technique for making remote-sensing observations of the inner heliosphere from around 5 solar radii all the way out to 2-3 AU from the Sun. • Aberystwyth has been and continues to be involved with many IPS-based experiments and will continue to do so. • The IPS experiment on LOFAR still needs further development to perform additional and cross-correlation two-site/multi-site observations, for automatic pipelining, automated scheduling, and multi-beam capacity; it is still very early days and commissioning is under way… • Plans for LOFAR observations of Faraday rotation (FR). • Preliminary LOFAR data do look very promising with further observations planned through the Autumn; watch this space!!!

  26. Final Acknowledgements Aberystwyth University thanks the Science and Technology Facilities Council (STFC) in the UK for their rolling and standard grants funding to the Institute of Mathematics and Physics (IMAPS) for continued solar wind and inner-heliosphere research.The University of California, San Diego (UCSD) acknowledges current and recent funding from NASA award NN11AB50G, and NSF awards ATM-0852246 and AGS-1053766. M.M.B. (joint UCSD and Aberystwyth University) also acknowledges an NSF SHINE Postdoctoral Fellowship award ATM-0925023. Thanks for listening! Further Info… LOFAR:http://www.lofar.org/ IPS:http://ips.ucsd.edu/ General:http://www.spacephysicist.com/

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