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4-station ultra-rapid EOP experiment with e-VLBI technique and automated correlation/analysis

1st International VLBI Technology Workshop MIT Haystack Observatory 22-24 October 2012. 4-station ultra-rapid EOP experiment with e-VLBI technique and automated correlation/analysis. Shinobu Kurihara (GSI), Kentaro Nozawa (GSI/AES), Rüdiger Haas (OSO),

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4-station ultra-rapid EOP experiment with e-VLBI technique and automated correlation/analysis

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  1. 1st International VLBI Technology Workshop MIT Haystack Observatory 22-24 October 2012 4-station ultra-rapid EOP experiment with e-VLBI techniqueand automated correlation/analysis Shinobu Kurihara (GSI), KentaroNozawa (GSI/AES), RüdigerHaas (OSO), Jim Lovell (UTAS), Jonathan Quick (HartRAO), Thomas Hobiger (NICT)

  2. Overview • Purpose: To produce dUT1/EOP as soon as possible • Data transfer (real-time or near real-time) by Tsunami UDP protocol to Tsukuba correlator • Data conversion Mark5 to K5 • Distributed K5 software correlation processing • Automated analysis by C5++

  3. Background • Started in 2007, for dUT1 measurement as Japan-Fennoscandian projectTsukuba/Kashima–Onsala/Metsähovi • 2009~, behind a regular IVS session a continuous dataset of dUT1 was derived by a “sliding window” approach [S. Matsuzaka, et al.: IVS GM2010] • Sep. 2011, we succeeded in 15-day continuous dUT1 measurement (Tsukuba-Onsala) in IVS CONT11 campaign • Nov. 2011, Tsukuba–Onsala–Hobart3-station/2-baseline for Xp, Yp & dUT1 [K. Kokado, et al.: IVS GM2012]

  4. Dataflow Onsala Hobart Tsukuba Stations Data transfer Data transfer K5 data Data transfer Mark5B data Mark5B data K5 data Lustre File System NFS Data conversion Correlator Data conversion Mark5A data Mark5A data K5 data K5 data 8 conversion servers Correlation Correlation 16 correlation servers/ 48 sockets Management Serverto control data transfer, conversion, correlation and analysis Correlator outputs Analysis AnalysisServer Analysis (dUT1 & Polar motion)

  5. Analysis strategy ~ sliding window To derive a continuous dataset of EOP/dUT1 Session start : one correlator output of each baseline 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 Tsukuba-Onsala Tsukuba-HartRAO Tsukuba-Hobart HartRAO-Onsala : Solutions (dUT1)

  6. Analysis strategy ~ sliding window Session start : one correlator output of each baseline 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 Tsukuba-Onsala 6 hours window Tsukuba-HartRAO Tsukuba-Hobart HartRAO-Onsala Solutions (dUT1) Set a “sliding window”, which means one period of correlator output used in one analysis.

  7. Analysis strategy ~ sliding window Session start : one correlator output of each baseline 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 Tsukuba-Onsala 6 hours window Tsukuba-HartRAO Tsukuba-Hobart HartRAO-Onsala Solutions (dUT1) UT1-UTC 03:00 04:00 05:00 06:00 Time

  8. Analysis strategy ~ sliding window Session start : one correlator output of each baseline 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 Tsukuba-Onsala 6 hours window Tsukuba-HartRAO Tsukuba-Hobart HartRAO-Onsala Slide forward Solutions (dUT1) New corr. outputs UT1-UTC 03:00 04:00 05:00 06:00 Time

  9. Analysis strategy ~ sliding window Session start : one correlator output of each baseline 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 Tsukuba-Onsala 6 hours window Tsukuba-HartRAO Tsukuba-Hobart HartRAO-Onsala ….. Solutions (dUT1) ….. UT1-UTC 03:00 04:00 05:00 06:00 Time

  10. Review: 3-station Ultra-rapid EOP • The first multi-baseline U-EOP exp. • Onsala-Tsukuba-Hobart 3 stations, but 2 baselines, due to software • Nov. 29-30 in 2011 • Failed in real-time data transfer and data processing  Tsukuba Onsala Hobart

  11. Result of 3-station U-EOP ~ offline processing dUT1 Avg. sigma 45.2 usec Xpole Avg. sigma 0.945 mas Ypole Avg. sigma 0.795 mas

  12. What’s new? 4-stations/6-baseline network • To add HartRAO as the 4th station •  Good network environment ~1 Gbps • Program modifications for 4-station experiment • Analysis software c5++ βupdated version • Support multi-baseline • User can decide which parameters to estimate • Support SINEX output Tag-along by sked program

  13. Recent ultra-rapid EOP experiments * +Hb means Hobart is tagged along Hh: HartRAO 26-m On: Onsala 20-m Ts: Tsukuba 32-m Hb: Hobart 12-m “Tag along” means to add one station into the original schedule without any effects on the other stations.

  14. Number of scans and obs. IVS-R1.554 on October 11, 2012 Tag along by sked * Scans between other station is also included. The original schedule is not optimized for Hobart.  Cause imbalance of the # of obs. # observations (baselines) correlated / scheduled The E-W baseline accounts for 70%. A dedicated experiment with an optimized schedule is needed to avoid the imbalance.

  15. How many sol’ns were derived within a short latency? All of processing (trans., conv., corr. & analysis) was done quite smoothly in near real-time. IVS-R1.555 on October 15, 2012 + Hobart (tag-along) 90% Latency: time elapsing from the end of last scan in a sliding window to deriving a solution About 90% of solutions were derived within 10 minutes!   

  16. R1.555 on Oct 15 U-EOP exp. Comparison between C5++ and CALC/SOLVE First half: start ~ 6:00 am outliers? 900 usec consistent UT1-UTC (usec) C5++: 6-h sliding window (near real-time) Calc/Solve: 3-h piecewise linear Observed by 4 stations; Tsukuba, HartRAO, Onsala and Hobart, and all four stations data was used in all solutions.

  17. R1.555 on Oct 15 U-EOP exp. Comparison between C5++ and CALC/SOLVE whole duration: start ~ end UT1-UTC (usec) C5++: 6-h sliding window (near real-time) Calc/Solve: 3-h piecewise linear Observed by 4 stations; Tsukuba, HartRAO, Onsala and Hobart, and all four stations data was used in all solutions.

  18. R1.555 on Oct 15 U-EOP exp. Comparison between C5++ and CALC/SOLVE First half: start ~ 6:00 am outliers? Xpole (arcsec) Xpole (arcsec) consistent Ypole (arcsec) Ypole (arcsec) consistent outliers?

  19. R1.555 on Oct 15 U-EOP exp. Comparison between C5++ and CALC/SOLVE whole duration: start ~ end Xpole (arcsec) Xpole (arcsec) Ypole (arcsec)

  20. Webcams 3-D fringe plots

  21. www.spacegeodesy.go.jp/vlbi/dUT1/ Solution plots of dUT1 & polar motion

  22. ToDo and future plan • Evaluation of solutions • The size of a sliding window, 1h, 3h, 6h, … which is better? Further analysis is needed. • Comparison with other analysis software, ex VieVS, … • C5++ is still beta version, and further improvement is ongoing by T. Hobiger (NICT). • Further modification of management programs for stable operation is needed. • Correlation job management program has not completely supported the multi-baseline processing. • A dedicated 4-station experiment is planned on December 17-18, 2012.

  23. Summary • Onsala, Hobart, HartRAO and Tsukuba just started 4-station ultra-rapid EOP experiment this August.  • We succeeded in near real-time processing; data transfer, conversion, correlation and analysis smoothly.  • Tsunami, Lustre File System, C5++, …etc • About 90% of solutions were derived within 10 minutes after the last scan of a sliding window.  

  24. Thank you for your attention.

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