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Abstracts:
| Authors | Title | Abstract | Talk/ Poster |
|---|---|---|---|
| C.S. Jacobs (1), J.E. Clark (1), C. Garcia-Miro (2), S. Horiuchi (3), L.J. Skjerve (1), O.J. Sovers (1) (1) Jet Propulsion Laboratory, California Institute of Technology / NASA (2) Ingenieria y Servicios Aeroespaciales, Instituto Nacional de Tecnica Aeroespacial/NASA (3) C.S.I.R.O. Astronomy and Space Science/NASA | THE CELESTIAL REFERENCE FRAME AT X/KA-BAND | In order to extend the International Celestial Reference Frame from its S/X-band (2.3/8.4 GHz) basis to a complementary frame at X/Ka-band (8.4/32 GHz), we began an ongoing series of X/Ka observations starting in mid-2005 using NASA\'s Deep Space Network DSN) radio telescopes. We have detected 455 radio sources. We will report global astrometric results from the first 51 sessions. These sessions covered the full 24 hours of right ascension and declination down to -45 degrees. Source position accuracy is at approximately the part-per-billion level. We have developed an error budget which shows the main errors are caused by limited sensitivity, mis-modelling of the troposphere, uncalibrated instrumental effects, and the lack of a southern baseline. Sensitivity has been increased by improving pointing calibrations and by increasing the data rate four-fold. Troposphere calibration has been demonstrated at the mm level. Construction of instrumental phase calibrators for Ka-band began in recent months. We will show projections for the expected effect on the X/Ka frame as these improvements enter the production data stream. The research described in this paper was done under contract with NASA. Government sponsorship acknowledged. | T |
| Arthur Niell and the VLBI2010 Broadband Development Group | Status of the NASA VLBI2010 Proof-of-concept System | The first VLBI2010 antenna with broadband capability is nearing 'first light'. The antenna is complete and the new hardware is being installed. Observations will initially be made at X-band using the Westford antenna with standard geodetic S/X antenna and receiver, followed by observations using the broadband system on Westford. The status of the 12m implementation and plans for the next stage of development will be reported. | T |
| Alessandra Bertarini | Polarization Leakage: Final Result | 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 telescop | 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, Axel Nothnagel | Geodetic VLBI Intensive scheduling based on singular value decomposition | The scheduling of Very Long Baseline Interferometry (VLBI) observing sessions is a crucial step to obtain reliable results with the best possible accuracy. At present, there is no clear strategy for the scheduling of VLBI Intensive sessions for the purpose of dUT1 determination. Here, a new approach for scheduling one hour long Intensive VLBI sessions is presented based on singular value decomposition (SVD). The SVD is a tool that enables a detailed analysis of a matrix X by the decomposition into three matrices that contain the singular values as well as the left-singular vectors (a basis for data space of the matrix X) and the right-singular vectors (a basis for model space of the matrix X). Assuming a least-squares adjustment of the observations for a given schedule, the Jacobian matrix containing the partial derivatives of the functional model with respect to the unknown parameters can be built. The parameters that are usually estimated for an Intensive are: zenith wet delay at both stations, one relative clock offset and one rate as well as the phase of the Earth’s rotation, ∆U T 1. Here we present preliminary results of the scheduling strategy based on SVD. By performing SVDs of the Jacobian matrix, the geometrical concept of projections onto the model space and the data space is used to derive indicators of how precisely the model parameters are determined from the observations and how well the adjusted observations match the original ones. Thereby, a schedule is obtained that is – in sense of a least-squares adjustment – optimal for the parameters that are presumably estimated. | T |
| Hase, H., Behrend, D., Ma, C., Petrachenko, W., Schuh, H., Whitney, A. (V2PEG members) | The future global VLBI2010 network of the IVS | The VLBI2010 concept was developed by the International VLBI Service for Geodesy and Astrometry (IVS) in order to create the next generation VLBI system which meets the goals of the Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG). The performance goals of 1mm position error and 0.1mm/y site velocity error require new radio telescope designs, new VLBI receiving and recording systems, new concepts for data transmission and correlation, as well as completely updated software for scheduling, data analysis, and archiving. In December 2010 the IVS VLBI2010 Project Executive Group (V2PEG) conducted a survey among the IVS network stations to measure awareness of VLBI2010 and to find out about modernization plans towards VLBI2010. The analysis of this survey indicates that most of the IVS network stations are already planning the transition to VLBI2010. The survey showed that up to 20 new radio telescopes at 17 sites with full VLBI2010 compliance could become operational by 2017. By 2014/15 a sufficient number of VLBI2010-compatible radio telescopes will be available for initial continuous VLBI2010 operations. The survey also showed that many network stations need technical consultation about VLBI2010 and support letters to be successful with VLBI2010 initiatives on the administration and funding level. | 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 |
| Hana Spicakova | Terrestrial reference frame solutions with the Vienna VLBI Software VieVS | The Vienna VLBI Software (VieVS) has been developed at the Institute of Geodesy and Geophysics at TU Vienna since 2008. In this presentation, we present the module Vie_glob which is the part of VieVS that allows the parameter estimation from multiple VLBI sessions in a so-called global solution. We focus on the determination of the terrestrial reference frame (TRF) using all suitable VLBI sessions since 1984. We compare different analysis options like the choice of loading corrections or of one of the models for the tropospheric delays. The effect of atmosphere loading corrections on station heights if neglected at observation level will be shown. Time series of station positions (using a previously determined TRF as a priori values) are presented and compared to other estimates of site positions from individual IVS (International VLBI Service for Geodesy and Astrometry) Analysis Centers. | T |
| Manuela Seitz | Common realization of Terrestrial and Celestial Reference System | The International Celestial Reference System (ICRS) is realized through more than 25 years of VLBI observation data. The realization is referred to as International Celestial Reference Frame (ICRF). VLBI is the only space geodetic technique, which allows for observing extragalactic radio sources with high accuracy and therefore for the realization of the ICRS. Hence, it is also the only technique which links the ICRF and the International Terrestrial Reference Frame (ITRF). Even if consistency between ICRF and ITRF is aspired and achieved to a certain extent, ICRF and ITRF are not adjusted consistently in one adjustment so far. Inconsistencies between the frames are the consequence. The paper deals with the consistent realization of CRF and TRF. We present results from a combination of homogeneously processed VLBI, GNSS and SLR data. We discuss the computation strategy and the advantages of the TRF-CRF solution as well as the related Earth Orientation Parameters regards consistency and stability. But, we also critically assess the aspect of network deformation caused by local tie misfits at co-location sites, which is a crucial point in ITRF computation. | T |
| Mark Kaufman, A. Sinev | Rapid EOP calculations using VLBI data by means of VieVS software | Many years the Main metrological center of Russian Time, Frequencies and Earth rotation Service executes the rapid EOP data calculations on the basis of GNSS, VLBI and SLR observations. In 2011 we began to process of new series of VLBI data using VieVS software developed at the Institute of Geodesy and Geophysics (IGG), Vienna University of Technology. According to requirements of operative calculations (the fast automated processing of\r\nsingle session without participation of the operator), the control program\r\n\\textit{eop{\\_}start.m} was writen. Its functions are as follows.\r\n\r\n1. Argument -- only a NGS-file name. Operating parameters and options for\r\nVieVS are adjusted in advance for daily and hour sessions.\r\n\r\n2. Calculated EOP values and some related data are presented in one string\r\naccording to IVS EOP FORMAT, Version 2.2. This string is than connected to\r\none of two files (for daily or hourly sessions), containing long time\r\nseries. Introduction of a string in a chronological order or replacement of\r\nits earlier version is provided.\r\n\r\n3. According to requirements IVS EOP FORMAT, the control program\r\n\\textit{eop{\\_}start.m} makes reduction of calculated EOP values to the mean time of observed\r\nsession, calculation of daily rates of EOP and their errors, calculation of\r\ncorrelation factors between EOP components. A code designation of session\r\naccording to IVS \\textit{masterXX.txt} files and the list of t he used stations in a 2-letter code\r\nis made also.\r\n\r\n4. The information of outliers detected by the VIE{\\_}LSM module and also of\r\nproblem station (with many bad data) detected by \\textit{eop{\\_}start.m} are entering in OUT and\r\nOPT files. The new iteration of all process of calculations is then\r\nautomatically carried out.\r\n\r\nAny changes in blocks VieVS was not brought by development of the control\r\nprogram. Its task is receiving, processing and sending data without manual\r\nintervention. In rare case, however, the visual graphical analysis is\r\nrequired, which can be executed by means of VieVS. | T |
| Roger Cappallo | Correlator Post-processing Algorithms for VLBI2010 | Many of the characteristics of the new VLBI2010 observing system require changes to the post-processing software that is applied at the correlator. The principal areas of change lie in the phase cal tone distribution, the increased number of channels, broad RF band coverage that enables ionospheric estimation and removal, and linearly polarized feeds that are correlated against circularly polarized feeds from pre-existing antennas. The algorithmic and code changes that are being implemented in the fourfit fringe-fitting program will be discussed. | T |
| Volkmar Thorandt | VLBI Analysis at BKG | The VLBI group of the Federal Agency for Cartography and Geodesy (BKG) in Leipzig is part of the jointly operated IVS Analysis Center of BKG and the Institute for Geodesy and Geoinformation of the University of Bonn (IGGB). BKG is responsible for regular ubmissions of time series of Earth Orientation Parameters (EOP) and tropospheric parameters, the generation of daily SINEX \r\n(Solution INdependent EXchange format) files for 24-hours sessions and Intensive VLBI sessions, quarterly updated solutions to produce terrestrial and celestial reference \r\nframe realizations (TRF, CRF), and generating Intensive schedules (mainly Tsukuba-Wettzell). \r\nThe data processing steps are explained and also some problems in the procedure of data analysis are pointed out. | P |
| Jing Sun | Status and future plans for the VieVS scheduling package | The development of the new VLBI2010 network, which uses smaller and fast-slewing antennas observing at broader bandwidths, is progressing rapidly with several new radio telescopes currently being constructed or planned. The new VLBI2010 operating modes will require a scheduling strategies different from today. The VieVS scheduling package (VIE_SCHED) is a new scheduling software in Matlab which has been developed at the Institute of Geodesy and Geophysics of the Vienna University of Technology since 2010. Algorithms and models of source structure, slewing time calculation, SNR calculations, and cable wrap have been developed. We generate different schedules and test these through simulations in order to evaluate what is the best observing strategy for the next generation VLBI network. These schedules differ in terms of number of observations and scans, slew time intervals, sky coverage at the individual stations, as well as coverage of the celestial sphere with sources. We also compare the schedules generated by VIE_SCHED with schedules generated with the SKED software, and the differences are analyzed. The planned future developments of VIE_SCHED include an option to analyze the covariance information and allow to consider sites with multiple antennas. We also plan to develop the graphical interface to make it easy to use. | T |
| John Gipson | Report on IVS Working Group 4: Data Structures | I describe the proposed data structure for storing, archiving and processing VLBI data. In this scheme, most VLBI data is stored in NetCDF files. NetCDF has the advantage that there are interfaces to most common computer languages including Fortran, Fortran-90, C, C++, Perl, etc, and the most common operating systems including linux, Windows and Mac. The data files for a particular session are organized by special ASCII "wrapper" files which contain pointers to the data files. This allows great flexibility in the processing and analysis of VLBI data, and also allows for extending the types of data used, e.g., source maps. I discuss the use of the new format in calc/solve and other VLBI analysis packages. I also discuss plans for transitioning to the new structure. | T |
| Christopher Beaudoin | Sensitivity evaluation of two VLBI2010 candidate feeds | The VLBI2010 effort will usher in a new generation of geodetic VLBI observing systems possessing far more bandwidth than their predecessors. As such, MIT Haystack Observatory has been actively involved in the evaluation of broadband microwave feeds for the new Patriot 12m antenna installed at the Goddard Geophysical Astronomical Observatory in Greenbelt MD, USA. In our contribution to the meeting, we will present sensitivity measurements of the Patriot 12m antenna as fed by the Chalmers University of Technology design (i.e. the Eleven antenna) as well as a new California Institute of Technology design (i.e. the quadridge feed horn - QRFH) both of which have been realized in hardware prototypes and are considered to be contending feeds for VLBI2010. | T |
| Vincenza Tornatore, Sergei Pogrebenko, Dimitry Duev,Ruediger Haas, Simon Casey, Guifre Molera | Single baseline GLONASS observations with VLBI: preliminary results | Several tests to observe signals transmitted by GLONASS (GLObal NAvigation Satellite System) satellites have been performed using the geodetic VLBI (Very Long Baseline Interferometry) technique. The radio telescopes involved in these experiments were Medicina (Italy) and Onsala (Sweden), both equipped with L-band receivers. Observations at the stations were performed using the standard Mark4 VLBI data acquisition rack and Mark5A disk-based recorders. The goals of the observations were to develop and test the scheduling, signal acquisition and processing routines to verify the full tracking pipeline, foreseeing the cross-correlation of the recorded data on the baseline Onsala-Medicina. The natural radio source 3c286 was used as a calibrator before the starting of the satellite observation sessions. Delay models, including the tropospheric and ionospheric corrections, which are consistent for both far- and near-field sources are under development. Correlation of the calibrator signal has been performed using the DiFX software, while the satellite signals have been processed using the narrow band approach with the Metsaehovi software and analysed with a near-field delay model. Delay models both for the calibrator signals and the satellites signals, using the same geometrical, tropospheric and ionospheric models, are under investigation to make a correlation of the satellite signals possible. | P |
| Franz Kirsten | Proper motion measurement of pulsars using multi-epoch VLBI mappings of M15 | The globular cluster M15 hosts two low-mass X-ray binaries (LMXB) and at least eight millisecond pulsars (MSP) detected via pulsed radio searches. Using multi-epoch 1.6 GHz VLBI observations at high spectral resolution, we detect the already known MSPs and perform a model independent proper motion analysis. Furthermore, we search for new radio sources being potential candidates for new LMXBS or MSPs in the vicinity of the core of M15. Combining the proper motion results of all sources under consideration we will be able to further constrain the central mass distribution in the cluster and, in case of high proper motions near the core, find further evidence for the central object being an intermediate mass black hole. I will present preliminary results from the first three of a total of six observation epochs. | P |
| Tobias Nilsson | Status and future plans for the Vienna VLBI Software VieVS | The Vienna VLBI Software (VieVS) is a new VLBI analysis software which has been developed at the Institute of Geodesy and Geophysics of the Vienna University of Technology since 2008. In this software, which is written in Matlab, the most recent IERS Conventions and are implemented, and through a graphical user interface it is easy to use. Lately, two new modules have been added to the official version of VieVS. One is a simulation module (VIE_SIM) which allows to create simulated VLBI observations. The other is a global solution module (VIE_GLOB) which can be used for combining several sessions in a global solution in order to derive e.g. a terrestrial and/or a celestial reference frame. In this presentation an overview of VieVS and its current status will be given and its performance will be demonstrated by showing selected results. We also discuss the planned future developments of VieVS. These include the possibility to use external tropospheric delays obtained, e.g. by ray-tracing through numerical weather models, to use external ionospheric corrections from, e.g. GNSS TEC maps, and to implement a Kalman filter solution. We also plan to cover earlier steps in the VLBI data processing chain, like ambiguity resolution, which have not been considered so far in VieVS. | T |
| Geraldine Bourda | Towards an accurate alignment of the VLBI frame and the future Gaia optical frame: Global VLBI observations status to image candidate sources | The space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be important to align the Gaia and VLBI frames with the highest accuracy. However, the number of quasars that are bright in optical wavelength (for the best position with Gaia), that have a compact core (to be detectable on VLBI scales), and that do not exhibit complex structures (to ensure a good astrometric quality), is currently rather limited (Bourda et al. 2008). It was hence realized that the densification of the list of such objects was necessary. Accordingly, we initiated a multi-step VLBI observational project, dedicated to finding additional suitable radio sources for aligning the two frames. The sample consists of ~450 optically-bright radio sources, which have been selected by cross-correlating optical and radio catalogs. The initial observations, aimed at checking whether these sources are detectable with VLBI, and conducted with the European VLBI Network in 2007, showed an excellent ~90% detection rate (Bourda et al. 2010). The second step, dedicated to extract the most point-like sources of the sample, by imaging their VLBI structures, was initiated in 2008. About 25% of the detected targets were observed with the Global VLBI array during a pilot imaging experiment, revealing ~50% of them as point-like sources on VLBI scales (Bourda et al. 2011). The rest of the sources were observed in March and November 2010 with the final imaging experiment planned in February 2011. In this paper, we present the results of these two imaging campaigns from 2010. And finally, the third step of this project, dedicated to measuring accurately the VLBI position of the most point-like sources of the sample, will be engaged in 2011. | T |
| Martin Ettl, Alexander Neidhardt, Matthias Mühlbauer, Walter Alef, Ed Himwich, Christopher Beaudoin, Christian Plötz, Arpad Szomoru | Concepts for continuous quality monitoring and station remote control | 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. | 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 | New remote control technologies for VLBI observations offers the possibilities of remote observations. This means that an operator has not to be on location of the telescope all the time (remote observation). This also allows to control more than one telescope by one operator(shared observation). At Wettzell also completely unattended observations have been done especially for the weekend sessions for over 2 years now. The development goal is to simplify operational workflows in combination with general control structures. These new observation control strategies are not limited to VLBI. They can also be applied to other geodetic space techniques such as SLR which are necessary to realize the Global Geodetic Observing System (GGOS). The demand for continuous and reliable observations requires to ease inconvenient night and weekend shifts. Remote controlled and autonomous observations will become more important in the future. The state-of-the-art software for control and monitoring is publicly available for testing and further developments. The most recent release integrates several new and comfortable features to support the daily work of an operator. | T |
| 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 dealing with system specific station commands and individual setup procedures. Neither the scheduler nor the correlator nor the analyst get a real-time feedback about system parameters during a session. Remotely induced changes in schedules after the start of a session are impossible. For future scientific applications more flexibility in the session control would optimize the station resources. Therefore a proposed shared-observation control of the global network of radio telescopes will be an advantage. Remote attendance/control as well as completely unattended-observations will become a necessity for VLBI2010 observation programs. To approach the goal of remote controlled VLBI operation the Geodetic Observatory Wettzell in cooperation with the Max-Planck-Institute for Radio Astronomy in Bonn are developing a software extension for remote control to the existing NASA Field System. The status of this developments allow already regularly remote controlled observations at Wettzell. The software extension was also tested in both ways in geodetic VLBI session between Wettzell, Germany and Concepción, Chile. The Intensive-sessions during weekends from Wettzell with Tsukuba are regularly operated remotely. The experiences gathered by these different session setups have led to new features like automatic connection reestablishment and internet performance measurements. Future developments for an authentication and user role management will be subject of the upcoming NEXPRES project. | P |
