Technical description of intensive UT1 solution gsiint2b Last update: 05 April, 2013 1. Purpose of solution: Ultra-rapid determination of UT1-UTC from the IVS INT2 sessions. 2 Analysis Center: Geospatial Information Authority of Japan (GSI) 3. Short narrative description of solution: The intensive solution gsiint2b is for the ultra-rapid estimation of UT1 from the IVS-INT2 sessions. Most sessions consist of about 40 observations on one baseline. The solution includes all usable INT2 sessions since 2003.04.09. The rapid solution of INT2 is submitted within a few minutes after the observing session. The processing is automatically implemented by the K5 correlation software and an analysis software. The analysis software, which is called c5++, is compliant to the IERS Conventions 2010[1]. All parameters are estimated by a least-squares estimation using a Gauss-Markov model. Outliers were detected and eliminated by simple 3-sigma criteria before re-iterating the process. For ultra-rapid solutions, predicted values of Xp/Yp are used as a priori pole. The Vienna mapping function (VMF1) [2] is applied for troposphere correction modeling. 3a. Differences with respect to previous (gsiINT2a) solution: The analysis software c5++ that is used in our analysis process was upgraded for the compliance with the IERS Conventions 2010. Furthermore, the flexible parameterization and SINEX input/output with variance/covariance matrix were supported. 4. Estimated parameters: a. celestial frame: No b. terrestrial frame: No c. earth orientation: UT1-UTC d. zenith troposphere: A zenith wet delay offset per station e. troposphere gradient: No f. station clocks: Coefficients of the second order polynomial of clock functions. g. baseline clocks: No 5. Celestial reference frame: a. a priori source positions: ICRF2 b. source positions adjusted in solution: No c. solution identification or reference: ICRF2 6. Terrestrial reference frame: a. a priori station positions: VTRF2008 The Tsukuba 32-m position after the March 11 earthquake in 2011 is applied the post earthquake correction to the VTRF a priori [3]. b. a priori station velocities: VTRF2008 velocity field c. reference epoch: 2000.0 d. station positions/velocities adjusted in solution: No e. solution identification or reference: VTRF2008 7. Earth orientation: a. a priori precession model: IERS Conventions 2010 b. a priori nutation model: IERS Conventions 2010 c. a priori short-period tidal variations in x, y, UT1: IERS Conventions 2010 d. a priori UT1 and polar motion: finals2000A.daily.snx, which is just converted from the IRES Rapid Service/Prediction Center's standard format into SINEX. http://maia.usno.navy.mil/ser7/finals2000A.daily 8. A priori geophysical models: a. troposphere: VMF1 for dry and wet delays b. solid Earth tide: IERS Conventions 2010 c. ocean loading: FES2004 model d. pole tides: IERS Conventions 2010 e. atmosphere loading: Created by http://geophy.uni.lu/ggfc-atmosphere/tide-loading-calculator.html f. antenna thermal deformation: IVS antenna thermal deformation model [4]. g. axis offsets: Values of the official list of VLBI antenna axis offsets issued by the IVS Analysis Coordinator (http://vlbi.geod.uni-bonn.de/IVS-AC/Conventions/antenna-info.txt) 9. Data type: Group delays 10. Data editing : Automatic ambiguity resolution using X/S band data only when both quality flags show no errors. Meteo data and cable cal are automatically extracted from the log files. 11. Data weighting: Observations are weighted by their wet mapping function values. 12. Standard errors reported: Formal errors at the one sigma level are derived from a least-squares adjustment. 13. Software: c5++ beta version, revision date 30 September, 2012 References [1] Hobiger, T., T. Otsubo, M. Sekido, T. Gotoh, T. Kubooka, and H. Takiguchi, Fully automated VLBI analysis with c5++ for ultra-rapid determination of UT1, Earth Planets Space, 45(2), 75-79, 2010. [2] Boehm, J., B. Werl, H. Schuh, Troposphere mapping functions for GPS and very long baseline interferometry from European Centre for Medium-Range Weather Forecasts operational analysis data, Journal of Geophysical Research, 111, B02406, 2006. [3] MacMillan, D., D. Behrend, S. Kurihara, Effects of the 2011 Tohoku Earthquake on VLBI geodetic measurements, IVS 2012 General Meeting Proceedings, 440-444, 2012. [4] Nothnagel, A., Modelling of Radio Telescopes for Geodetic and Astrometric VLBI, Journal of Geodesy, 83, 787-792, 2009. ---- Tsukuba VLBI Analysis Center Contact: Shinobu Kurihara (skuri@gsi.go.jp)