MATERIALES Y MÉTODOS

DETIC NETWORKS

RESEARCH GROUP: (ITRF-Tie vectors) Luca Vittuari, Pierguido Sarti, Claudio Abbondanza, Monia Ne- gusini, Maria Alessandra Tini (Network analysis) Maurizio Barbarella, Stefano Gandolfi, Antonio Zanutta, Luca Poluzzi, Luca Tavasci

KEYWORDS: ITRF, IERS, Tie vectors, ETRF, RND, NRTK

The realization of precise and reliable global geo- detic reference frames is one of the innovations that have most contributed to the efficiency of po- sitioning techniques, i.e. for monitoring surveys, land surveying and cadastral procedures, the stack- ing-out of large infrastructures, or for maritime, terrestrial and aerial navigation.

Starting from the initial applications exclusively conducted by research institutions, we can now observe a wide dissemination of the techniques of space geodesy for consumer applications, and it is sufficient to cite satellite car navigation systems or applications based on global positioning installed in smartphones or tablets PC. The reference frame more accurate is the International Terrestrial Ref- erence Frame (ITRF) maintained by the Inter- national Earth Rotation and Reference Systems Service (IERS). The update of ITRF, entirely de- pends on the voluntary effort of a large number of agencies and research infrastructures, this creates a fundamental relationship between public and private, national and global technical services. This reference frame is now the backbone also for the realization of national reference frames. As exam- ple in Italy the Presidency of the Council of Min- isters established by the Decree of 10 November 2011, the institution of the Rete Dinamica Nazi- onale (RDN) as official national reference frame, composed by 99 GNSS permanent stations. A team of DICAM studied in collaboration with the Institute of Radio Astronomy (IRA-INAF) the ensemble of high-accuracy survey methodologies and geometrical/statistical procedures necessary for the measure of eccentricity vectors between the reference points (RP) of co-located geodetic instruments and a WG was established in 2003 within the IERS - IAG Sub-Commission 1.2. Moreover DICAM is involved both in real time GNSS network for NRTK positioning and for the RDN analysis by means of the most advanced sci-

Fig. 1. Topographical measurements for the estimation of the tie-vectors GPS-VLBI at the IRA-INAF observatories of Medicina (BO) and Noto (SR).

Fig. 2. Residual velocities in ETRF of GNSS permanent stations belonging the Rete Dinami- ca Nazionale (RDN).

MAIN PUBLICATIONS

Abbondanza C., Negusini M., Sarti P., Vittuari L.. (2006). An investigation on a GPS-based ap- proach to local tie computation. International VLBI Service for Geodesy and Astrometry 2006 General Meeting Proceedings. Fourth IVS Gen- eral Meeting. Concepción, Chile. January 9-13, 2006. (vol. NASA/CP-2006-214140, pp. 162 - 166). -: NASA Conference Publication (US). Abbondanza C., Vittuari L., Sarti P., Negusini M.. (2007). An Analysis of Local Tie Vectors’ Tem- poral Evolution and Site Stability at Medicina Observatory through Terrestrial and GPS-based Observations. GEOWISSENSCHAFTLICHE MITTEILUNGEN. 18th European VLBI for Geodesy and Astrometry Working Meeting. Vi- enna. 12-13 April 2007. (vol. 79, pp. 188 - 183). ISSN 1811-8380. VIENNA: edited by J. Boehm, A. Pany, and H. Schuh (Austria).

Barbarella M., Cenni N., Gandolfi S., Ricucci L., Zanutta A., (2009), Technical and scientific as- pects derived by the processing of GNSS networks using different approaches and software, ION GNSS 22th International Technical Meeting of the Satellite Division, 23-25 September 2009, Sa- vannah, GA, USA, 2677-2688.

Barbarella M., Gandolfi G., Ricucci L, Zanutta A., (2009) The new Italian geodetic reference network (RDN): a comparison of solutions using different software packages; http://www.euref.eu/ symposia/2009Florence/06-03-p-gandolfi.pdf Barbarella M., Gandolfi S., Ricucci L., 2010, Esperienze di calcolo della Rete Dinamica Na- zionale, Bollettino SIFET (ISSN 1721-971X), 2010, 2, 27-43.

Bolli P., Montaguti S., Negusini M., Sarti P., Vittu- ari L., Deiana GL. (2006). Photogrammetry, laser scanning, holography and terrestrial surveying of the Noto VLBI dish. International VLBI Ser- vice for Geodesy and Astrometry 2006 General Meeting Proceedings. Fourth IVS General Meet- ing. Concepción, Chile. January 9-13, 2006. (vol. NASA/CP-2006-214140, pp. 172-176).-: NASA Conference Publication (US).

Dawson J., Sarti P., Johnston G. M., Vittuari L.. (2007). Indirect approach to invariant point de- termination for SLR and VLBI systems: an assess-

441 ISSN: 0949-7714. DOI 10.1007/s00190- 006-0125-x.

Montaguti S., Vittuari L., Sarti P., Negusini M. (2007). Medicina and Noto VLBI Radiotel- escopes: gravitational deformations evaluated with terrestrial laser scanning. GEOWISSEN- SCHAFTLICHE MITTEILUNGEN. Pro- ceedings of the 18th European VLBI for Geodesy and Astrometry Working Meeting. Vienna. 12-13 April 2007. (vol. 79, pp. 4-9). VIENNA: edited by J. Boehm, A. Pany, and H. Schuh (Austria). Sarti, P., Abbondanza, C., Legrand, J., Bruyninx, C., Vittuari, L., Ray, J., 2013, Intra-site motions and monument instabilities at Medicina ITRF co-location site, Geoph. J. Int., vol. 192, p. 1042- 1051, ISSN: 0956-540X, doi: 10.1093/gji/ ggs092. pp. 1042-1051.

Sarti P., Sillard P., Vittuari L. (2004) - Surveying co-located Space Geodesy techniques for ITRF computation, Journal of Geodesy, vol.78, n. 3, Springer, 210-222. DOI 10.1007/s00190-004- 0387-0.

Vittuari L., Sarti P., Sillard P., Tomasi P., Negusini M.. (2005). Surveying the GPS-VLBI Eccentricity at Medicina: Methodological Aspects and Practi- calities. IERS Technical Note. Proceedings of the IERS Workshop on site co-location. Matera. Italy, 23 - 24 October 2003. (vol. 33, pp. 38 - 48). ISBN: 3-89888-793.

RESEARCH PROJECTS

PRIN 2007: “Uso degli osservatori geodetici co-lo- cati VLBI-GPS per l’omogeneizzazione ed il con- fronto di serie storiche derivate da PS INSAR e livellazione geometrica, nello studio dei movimenti del suolo a scala regionale” (National PI A. Capra). FARB 2012 – Linea 1 Studi di fattibilità. Titolo della ricerca: “Metodi matematici per l’esplorazi- one ambientale sostenibile”. PI: V. Simoncini. CISIS 2011 e 2012: Monitoraggio della Rete Di- namica Nazionale Italiana (RDN)

CONTACTS ITRF tie-vectors: [email protected] [email protected]

National reference networks: [email protected]