1. Implementation and design of a web-based GNSS data management system at Hartebeesthoek Radio Astronomy Observatory Z.O. Mashaba 1, L. Combrinck 2, O.J. Botai 3 1 Hartebeesthoek Radio Astronomy Observatory (HartRAO), P O Box 443, Krugersdorp 1740, South Africa, zinhle@hartrao.ac.za 2 Hartebeesthoek Radio Astronomy Observatory (HartRAO), P O Box 443, Krugersdorp 1740, South Africa, ludwig@hartrao.ac.za 3 Centre for Geoinformation Science, Department of Geography, Geoinformatics and Meteorology, University of Pretoria, South Africa, joel.botai@up.ac.za 10 th Inkaba yeAfrica/!Khure Africa (AEON) Conference/Workshop Lord Milner Hotel, Matjiesfontein - Karoo 29 September – 3 October 2014

2. The Hartebeesthoek Radio Astronomy Observatory (HartRAO) has four collocated space geodetic techniques (GPS, VLBI, SLR and LLR). The geodetic data collected by the instruments are required to be available in near-real time. This project specifically focuses on Global Navigation Satellite Systems (GNSS) data management. Background

3. HartRAO is a scientific institution with instruments doing measurements at a high temporal resolution (i.e. seconds, minutes). The measurements are in various formats and archived at various locations in the server, computers and disks. Accessing this data currently takes a lot of time due to lack of systematic guidelines or system to facilitate faster data retrieval. As a result, a data management system (including quality analysis & visualization) is required to help users to gain easy access to these data sets. Background

4. The regional GNSS network archived by HartRAO. Background

5. Data acquisition process Background

6. The teqc and GAMIT/GLOBK software are utilized at various steps during data processing. The GNSS data products are then moved to the interactive web map. This procedure is designed to minimize human intervention and limit inconsistencies in data processing. Methodology

7. Results (Precipitable Water Vapour)

8. Results (Data products) Sky plots Displays the motions of satellites along an orbit plane.

9. Time Series plot Depicts the direction in which the station is moving in terms of N, E and Height over time. Results (Data products)

10. Quality check report Teqc program provides quality check information about the GNSS signals. Results (Data products)

11. Results (Web-Map) Results (Web-Map)

13. GNSS remote monitoring system

14. Data are not as useful to users if its not updated in real time and loses its value. Implementing an automated data management system aids in solving these problems. Such a data management system should be implemented for the other space geodetic data (VLBI, SLR and LLR) at HartRAO in future for researchers and the public to gain easy access to data and data products. This project contributes towards the establishment of a geodetic analysis centre. Conclusions and Recommendations

15. We appreciate support towards this project from the Inkaba yeAfrica project, the NRF and HartRAO. Acknowledgments