Table of contents
Abstracts:
| Authors | Title | Abstract | Talk/Poster |
| Martin Ettl, Alexander Neidhardt, Matthias Mühlbauer, Christian Plötz, Hayo Hase, Sergio Sobarzo, Cristian Herrera, Eric Oñate, Pedro Zaror, Felipe Pedreros, Octavio Zapato | Experiences with regular remote attendance towards new observation strategies | Current VLBI observations are controlled and attended locally at the radio telescopes on the basis of pre-scheduled session files. Operations have to deal with system specific station commands and individual setup procedures. Either the scheduler nor the correlator or analyst get real-time feedback about system parameter during a session. Changes in schedules after the start of a session by remote are impossible or at least quite difficult. For future scientific approaches a more flexible mechanism would optimize the usage of resources at the sites. Therefore shared-observation control between world-wide telescopes, remote attendance/control as well as completely unattended-observations could be useful, besides the classic way to run VLBI observations. To reach these goals the Geodetic Observatory Wettzell in cooperation with the Max-Planck-Institute for Radio Astronomy (Bonn) develop a software extension to the existing NASA Field System for remote control. Meanwhile remote control possibilities are regularly used and established at Wettzell. Based on this technology the completely remote attended and controlled geodetic VLBI session between Wettzell, Germany and Concepción, Chile were successfully performed over 24 hours. Also the intensives on weekends are regularly operated by remote. These first tests are extraordinary valuable to gather information about the differences between VLBI systems and to measure the performance of internet connections and automatic connection re-establishments. In addition, future developments for an authentication and user role management will be realized within the upcoming NEXPRES project. | P |
| Martin Ettl, Alexander Neidhardt, Matthias Mühlbauer, Wlater Alef, Ed Himwich, Christopher Beaudoin, Christian Plötz, Arpad Szomoru | Concepts for continuous quality monitoring and station remote control | In the Work Package 5 of the third task in the newly funded “Novel EXploration Pushing Robust e-VLBI Services”–project (NEXPReS) the Technische Universitaet Muenchen realize concepts for continuous quality monitoring and station remote control in cooperation with the Max-Planck-Institute for Radioastronomy, Bonn. NEXPReS is a three-year project aimed at further developing e-VLBI services of the European VLBI Network (EVN), with the goal of incorporating e-VLBI into every astronomical observation conducted by the EVN. This project focus on developments of an operational e-control system with authentication and authorization. It includes an appropriate role management with different remote access states for future observation strategies. To allow a flexible control of different systems in parallel sophisticated graphical user interfaces are designed and realized. It requires also a session oriented data management. Because of the higher degree of automation additional system parameters and information is collected with a new system monitoring. The whole system for monitoring and control is fully compatible to the NASA field system as extension. The concept will be proofed with regular tests between Wettzell and Effelsberg. The project is scheduled for the coming three years. | T |
| Alexander Neidhardt, Martin Ettl, Helge Rottmann, Christian Plötz, Matthias Mühlbauer, Hayo Hase, Walter Alef, Sergio Sobarzo, Cristian Herrera, Ed Himwich | New observation strategies with e-control | With new remote control technologies it is not necessary anymore that the operator is on location. He can control the system from remote (remote observation). This technology can also be used to control more than one telescope by one operator. The control can be shared between operators (shared observation). At Wettzell also completely unattended observations have been done especially for the weekend sessions for over 2 years now. The goal is to simplify operational workflows in combination with general control structures. These new observation strategies are not only designed for VLBI. They also offer other space techniques new possibilities for technical realization of a Global Geodetic Observing System (GGOS). To realize continuous and reliable observations it is necessary to ease inconvenient night and weekend sifts. Remote and autonomous observations are necessary steps to reach this goal. Therefore the developed software for control and monitoring is offered to the community in releases for download. Several new and comfortable features are already implemented to support the daily work of an operator. | T |
| G. Kronschnabl, Hayo Hase, T. Klügel, A. Neidhardt, K. Pausch, W. Göldi | VLBI2010 – The TWIN radio telescope project at Wettzell, Germany | The Twin Telescope Wettzell Project is funded to be executed during the period of 2008−2011. The design of the TTW was based on the VLBI2010 vision of the corresponding IVS Working Group. In the first two project years the design passed the simulations with respect to its specifications and was approved for production. At the Geodetic Observatory Wettzell a thorough soil analysis was made in order to define the sites for the towers of the new radio telescopes. Meanwhile the construction work has begun and acceptance tests of several telescope parts, e.g. azimuth bearings, took place. The new radio telescopes are almost completely assembled and the progress is quite on time. In parallel to the construction work at the Wettzell site, the design work and ordering of the different feed options are under progress. | P |
| Christopher Jacobs | X/Ka Celestial Frame | TBD | T |
| Arthur Niell | Observations with a VLBI2010 System | TBD | T |
| Alessandra Bertarini | Polarization Leakage: Final Results | The precision of geodetic and astrometric measurements is degraded by instrumental errors of which polarization leakage is one of the larger.Its effect can be corrected in the data provided one knows the leakage characteristics of the stations. I describe resulting polarization leakage measurements and the algorithm that was implemented to correct for their effect on the geodetic delay measurables. From the measured leakage terms, one would expect polarization leakage to affect the group delay measurements by 0.5~ps to 7~ps, depending on the stations involved in the baseline. This proved to be below the statistical noise in a single VLBI experiment and so the improvement from the correction could not be detected. Polarization leakage was found, unespectedly, not the dominant source of non-closing errors. | T |
| Walter Alef | Bonn correlator status report | We will present the status of the Bonn MPIfR/BKG VLBI correlator center including a field report on how the MK IV hardware correlator was replaced by the DiFX software correlator. | T |
| T. Hobiger(1), M. Sekido(1), T. Otsubo(2,1) , T. Gotoh(1), T. Kubooka(1), H. Takiguchi(1) and H. Takeuchi(3) (1) National Institute of Information and Communications Technology (NICT), Japan (2) Hitotsubashi University, Japan (3) Japan Aerospace Exploration Agency(JAXA), Japan | VLBI analysis with c5++ - status quo and outlook | Otsubo et al. (2002) have developed an analysis software package based on Java named CONCERTO4 which enabled the user to consistently process SLR, GPS and other satellite tracking data. Driven by the need to update the software and replace the existing Java code, VLBI was added as an additional module to this analysis package and renamed c5++. The software provides state-of-the-art modules for a variety of geodetic, mathematical and geophysical tasks that can be combined to a stand-alone VLBI application. Although many of these modules can be used for any of the space geodetic techniques, a couple of technique specific solutions (like relativity, antenna deformation, etc.) had to be coded exclusively for VLBI. We are going to discuss details of the software and its development and we are going to summarize how the automated analysis procedure of the real-time UT1 experiments has been realized with c5++. Other fields of applications for this software will be shown as well. We conclude our presentation with an outlook on future applications (including time and frequency transfer and space-craft navigation) as well as discuss the next steps towards a software package which allows combination of space geodetic techniques on the observation level. | T |
| Bill Petrachenko | VLBI2010: Status and Prospects | The current status and future prospects of VLBI2010 will be discussed from a technique point of view. | T |
| Oleg Titov (Geoscience Australia) Sebastien Lambert (Paris Observatory) | VLBI measurement of the secular aberration drift | Analysis of VLBI records of distant radio source signals allows to determine the proper motions of the extragalactic objects with an accuracy of a hundred microseconds of arc per year (~$\mu$as/yr). Such an accuracy is sufficient to investigate the aberration in proper motions of distant bodies due to the rotation of the Solar system barycentre around the Galactic centre. We analyzed geodetic and astrometric VLBI data to produce radio source coordinate time series using the CALC/SOLVE software package. We fitted vector spherical harmonic components of degree 1 and 2 to the velocity field made up of the proper motions of 555 sources of good observational history over the period 1990-2010. The acceleration vector has an amplitude of $6.4\pm1.5$~$\mu$as/yr and is directed towards equatorial coordinates $\alpha=263^{\circ}$ and $\delta=-20^{\circ}$. Within errors bars, the magnitude and the direction of the dipole component agree with predictions (magnitude 4--6 ~$\mu$as/yr, $\alpha=266^{\circ}$ and $\delta=-29^{\circ}$). | T |
| Oleg Titov (Geoscience Australia) Sebastien Lambert (Paris Observatory) | Optical spectra of the flat-spectrum radio sources measured at NTT telescope | We present the results of spectroscopic observations of 47 radio sources from the International VLBI Service (IVS) Reference Catalogue, made with the 3,58-meter European Southern Observatory New Technology Telescope (NTT). All of the radio sources are involved in observational VLBI programs to establish the celestial reference frame. Of the 47 sources observed we present 31 new redshifts. | T |
| Axel Nothnagel | TBD | TBD | T |
| Thomas Arzt | TBD | TBD | T |
| Judith Pietzner | TBD | TBD | T |
| Hayo Hase | TBD | TBD | T |
| Barry Geldzahler | TBD | TBD | T |
| Gino Tuccari | DBBC3 - Multigigabit Backend | DBBC3 is the multigigabit evolution of the DBBC backend system. The minimum instataneous band is 4GHz/IF with a typical output rate of 32 Gbps. | T |
| Lucia Plank, J. Boehm, H. Schuh | First steps of processing space VLBI data with VieVS | Since 2008 the VLBI group at the Institute of Geodesy and Geophysics (IGG) of the Vienna University of Technology has developed the Vienna VLBI Software VieVS which is capable to process geodetic VLBI data in NGS format. Constantly we are working on upgrading the new software, e.g. by developing a scheduling tool or extending the software from single session solution to a so-called global solution, allowing the joint analysis of many sessions covering several years. In this presentation we report on first steps to enable the processing of space VLBI data with the software. \r\nDriven by the recently increasing number of space VLBI applications, our goal is the geodetic usage of such data, primarily concerning frame ties between various reference frames, e. g. by connecting the dynamic reference frame of a space probe with the kinematically defined International Celestial Reference Frame (ICRF). Main parts of the software extension w.r.t. the existing VieVS are the treatment of fast moving targets, the implementation of a delay model for radio emitters at finite distances, and the adequate mathematical model and adjustment of the particular unknowns. Actual work has been done for two mission scenarios so far: On the one hand differential VLBI (D-VLBI) data from the two sub-satellites of the Japanese lunar mission Selene were processed, on the other hand VLBI observations of GNSS satellites were modelled in VieVS.\r\nBesides some general aspects, we give details on the calculation of the theoretical delay (delay model for moving sources at finite distances) and its realization in VieVS. First results with real data and comparisons with best fit mission orbit data are also presented.' | T |
| James Campbell | EVGA - Looking back at the early beginnigs | 31 years after the first European VLVI meeting for Geodesy and Astrometry it seems appropriate to take a - perhaps slightly nostalgic - look back at the early beginnings of a cooperative European effort to establish a regional VLBI network dedicated to geodetic, i.e. geodynamic in a broader sense, and astrometric reseach. | T |
| Rosa M. Torres | VLBA Determination of the Distance to Nearby Star-Forming Regions | We will present part of a very large ongoing effort to determine the distance and structure of all star-forming regions within several hundred parsecs of the Sun using multi-epoch VLBA observations. The main results are: (1) the distance to three of the most studied low-mass star-forming regions: Taurus, Ophiuchus and Serpens with accuracies one to two orders of magnitude better than the present values, and (2) the impact to accurate measurements to our understanding of the structure and dynamics of those nearby star-forming regions. | P |
| Stefanie Muehle | Recent Developments at the Joint Institute for VLBI in Europe (JIVE) | After an overview of the European VLBI Network (EVN) including new stations, upgrades and operational aspects, we will review the status and capabilites of the correlators at JIVE. The transition phase from the Mark IV hardware correlator to the SFXC software correlator has now reached the point where the first user experiments correlated on the SFXC correlator have been distributed. In addition, we will report on the expanded capabilities of real-time e-VLBI, which now comprises a significant fraction of EVN operations. | T |
| C.Tierno Ros, J. Boehm, H. Schuh | Use of GNSS-Derived TEC maps for VLBI observations | The ionospheric delay makes up a large fraction of observed VLBI group delays; it depends on the total number of free electrons (TEC) along the ray path. Usually, a correction can be applied by making simultaneous observations in both S and X band. However, this is not always possible. For such cases, the alternative of calculating the ionospheric correction from GNSS TEC maps is studied. A comparison of the ionospheric correction obtained from dual-band VLBI observations and from GNSS TEC maps is shown and first results will be presented if the ionospheric corrections derived from GNSS are applied to VLBI. | P |
