Orbital elements define the shape, size, and orientation of a satellite’s orbit, as well as the position of the orbiting satellite along the ellipse at a specific time. Currently, precise orbit determination relies solely on satellite observations. However, future plans involve equipping Genesis and Galileo satellites with Very Long Baseline Interferometry (VLBI) transmitters. This would enable to observe satellites with VLBI radio telescopes and allow to determine orbital elements from VLBI observations to satellites.This study investigates the potential of VLBI observations to satellites to contribute to the determination of orbital elements. In a first step, schedules, including satellite and quasar observations, are created using VieSched++. The Vienna VLBI and Satellite Software (VieVS) is used to simulate and analyze these schedules. To introduce the orbital elements in the Least Squares Adjustment, the partial derivatives of the position vector with respect to the orbital elements are needed. There are different approaches available for computing these partials, including numerical, analytical, or using partials obtained from the ORBGEN module in the Bernese GNSS software. Next, the partials of the position vector are utilized to determine the partial derivative of the time delay tau with respect to the orbital elements.This enables the estimation of orbital elements from simulated VLBI observations to satellites. The estimated parameters' quality is evaluated based on the mean formal errors and repeatabilities. Furthermore, the correlations between all orbital elements are examined.

Mission Genesis of the European Space Agency (ESA) has been approved for launch in 2027. Genesis will be the first satellite in orbit to have a dedicated Very Long Baseline Interferometry (VLBI) transmitter on board, next to Global Navigation Satellite System (GNSS) and Doppler Orbitography and Radiopositioning Integrated on Satellite (DORIS) receivers as well as a Satellite Laser Ranging (SLR) reflector; consequently, Genesis will realize a space tie combining all geometric space geodetic techniques. If perfectly calibrated, the space tie will enhance and improve local ties measured on the ground. The following scenario is possible: If the orbit of Genesis is determined from the satellite techniques alone, the station coordinates of the VLBI radio telescopes in the "satellite frame" can be derived by VLBI observations to Genesis, thereby assessing the tie with the "VLBI frame", realized with decades of VLBI observations to quasars. We present our plans to devise observing strategies for VLBI to reach accuracies as defined in the Genesis white paper. We start with our findings for VLBI transmitters on Galileo satellites, before we show the simulation results for the VLBI transmitter on Genesis. We illustrate the advantages of the Genesis satellite at 6000 km altitude compared to Galileo satellites in terms of sky coverage and accuracy of station coordinates, but also in terms of orbit estimation. Furthermore, we provide an outlook on geodetic parameters, which could not be determined with VLBI so far but will be possible with Genesis.

Very Long Baseline Interferometry (VLBI) transmitters on satellites are considered for future satellites of Global Navigation Satellite Systems (GNSS) as well as for the upcoming Genesis mission of the European Space Agency (ESA). In both concepts, VLBI observations to VLBI transmitters on the satellites can contribute to orbit determination, with the geometry of observations to Genesis advantageous compared to GNSS. With Galileo as one of the GNSS, we emphasise the importance of VLBI observations for the estimation of the right ascension of the ascending node Ω , which cannot be determined from GNSS alone. We find that Ω can be estimated with accuracies better than 50 μ as from 24 hour sessions with alternate observations to quasars and the Galileo satellite of interest. Station coordinates, on the other hand, can be determined from observations to three Galileo satellites with an accuracy at the centimetre-level or better from 24 hour sessions, again with alternate observations to the satellites and quasars for a better estimation of tropospheric parameters. Station coordinate results with VLBI observations to VLBI transmitters on satellites form the basis for frame tie and local tie determination. The transfer of space ties to local ties on the ground is of particular relevance for Genesis.

Equipping Galileo satellites with a VLBI transmitter (VT) will allow to observe satellites next to quasars with Very Long Baseline Interferometry (VLBI) radio telescopes. This concept will facilitate the direct estimation of the satellite orbits in the celestial reference frame. Moreover, these observations along with usual Galileo observations can be used to transfer the space tie between the VT and the antenna on the Galileo satellite to the Earth surface realizing the frame tie at the geodetic site with VLBI radio telescope and Galileo antenna. In this study, we assess the accuracy of that frame tie by simulating the estimation of station coordinates from VLBI observations to Galileo satellites next to quasars. We find that at least two or three satellites need to be equipped with a VT with the best results if all satellites with a VT are placed in the same plane. Concerning the ratio between satellite and quasar observations within a schedule, the results suggest that the optimal ratio is around 30% to 40% satellite observations out of the total number of observations in order to have enough observations for the estimation of the station coordinates but still enough quasar observations to ensure a sufficient sky-coverage for the estimation of troposphere parameters. The best scenario with two satellites yields repeatabilities for the east and north components between 7.5 and 10 mm, and for the up component between 9.5 and 12 mm. In case there is a third satellite with a VLBI transmitter in the same plane, the repeatabilities are reduced by up to 2 mm for the horizontal components and up to 3 to 4 mm for the up component. Rotating the schedules over the constellation repeat cycle of Galileo of 10 days reveals that there are differences between the individual days, but there are no days with a significantly worse precision of the estimated station coordinates. Graphical Abstract

Over the last years, ideas of installing a dedicated Very Long Baseline Interferometry (VLBI) transmitter on board of the second generation of Galileo satellites have been proposed. The mounting of such a transmitter on future satellites raises scientific questions and opens new opportunities of extending the current VLBI research with observations to geodetic satellites. These observations allow combining the satellite and the quasar frame due to the unique opportunity of determining the satellite orbit in the International Celestial Reference Frame (ICRF).In this contribution, we present the estimation of orbit arcs based on VLBI observations combined with GNSS measurements. For this purpose, schedules including satellite and quasar observations, are created with the scheduling software VieSched++. These schedules are simulated and analyzed with the Vienna VLBI and Satellite Software (VieVS). In the analysis the partial derivatives of the state vector of the satellite with respect to the orbital elements, obtained from the module ORBGEN in Bernese, are used in VieVS for calculating the partial derivatives of the time delay with respect to the orbital elements. This approach allows to estimate the orbital elements from simulated VLBI observations. The quality of the estimated parameters is investigated and assessed based on the mean formal errors and the repeatabilities.In a further step there is the option to combine the results from VieVS and Bernese at the normal equation (NEQ) level using the ADDNEQ2 and retrieve fully consistent orbital parameters based on VLBI and GNSS observations.

Installing a VLBI transmitter on Galileo satellites will allow observing satellites in parallel to quasars with Very Long Baseline Interferometry (VLBI) telescopes. This offers a variety of new applications such as the direct determination of the absolute orientation of the satellite constellation with respect to the International Celestial Reference Frame (ICRF) and the improvement of the Terrestrial Reference Frame (TRF) exploiting the possibilities of direct high precision tying of the different space geodetic equipment. In preparation of these observations by enhancing the capabilities of the VLBI scheduling program VieSched++, we perform an evaluation study of observations of a Galileo satellite employing Dilution of Precision (DOP) factors. The idea is to introduce DOP factors in the decision process of VieSched++ after a thorough assessment of DOP factors for individual parameters. In our study, we choose an existing network of VLBI Global Observing System (VGOS) type telescopes for observing Galileo satellite GSAT0212 within a 24 h arbitrary session. Preparing the DOP factor analysis, we first carry out a theoretical study to investigate the VLBI sensitivity to satellite orbit displacements in the local orbital frame with normal (radial), tangential and cross-track direction. This analysis shows that the highest sensitivity of a satellite observation is that of the tangential component if the direction of the satellite track is parallel to the direction of the observing baseline. A satellite observation is most sensitive towards the cross-track component if these two directions are orthogonal to each other. The DOP factor analysis itself is performed separating the satellite position again into its three components and adding a separate DOP factor for the UT1-UTC (dUT1) parameter. The periods, where satellite observations are possible, were determined using VieSched++. At a later stage, these DOP factors will be used as an optimization criterion for the scheduling process. The DOP factors of potential observations from the chosen VGOS network to GSAT0212 reach minimum DOP values of 27.13 in normal, 1.49 in tangential, and 1.67 in cross-track direction and 0.45 for determining dUT1. With these results, which have confirmed intuitive considerations on the relative magnitudes, we have laid the groundwork for using DOP factors as driving criteria in the scheduling process of Galileo satellites embedded in regular VLBI observations of quasars.

Observing Earth-orbiting satellites additionally to natural extra-galactic radio sources with Very Long Baseline Interferometry (VLBI) radio telescopes offers a variety of new possibilities and allows expanding the research activities of this highly accurate technique. The combination of observations to satellites and quasars permit the determination of the satellite orbit from VLBI observations in the terrestrial as well as in the International Celestial Reference Frame. The latter is enabled by the unique capability of VLBI to determine Universal Time UT1. In this contribution for the first time, the precision of short satellite orbital arcs determined with simulated VLBI observations to Galileo satellites for different observation geometries using various VLBI networks and arc lengths is investigated. For this purpose, schedules including both, observations to quasars and satellites, are created using the scheduling software VieSched++. The simulations of the scheduled observations and the estimation of the satellite arcs are carried out using the Vienna VLBI and Satellite Software (VieVS). The quality of the estimated orbits is investigated and assessed based on the mean formal errors and the repeatabilities of the individual components of the satellite positions based on Monte Carlo simulations.

Over the last years, ideas have been proposed to install a Very Long Baseline Interferometry (VLBI) transmitter on one or more satellites of the Galileo constellation. Satellites transmitting signals that can be observed by VLBI telescopes provide the opportunity of extending the current VLBI research with observations to geodetic satellites. These observations offer a variety of new possibilities such as high precision tying of space geodetic techniques but also the direct determination of the absolute orientation of the satellite constellation with respect to the International Celestial Reference Frame (ICRF) and have implications on the determination of long-term reference frames. This contribution provides a visibility study of the Galileo satellites from a VLBI network. The newly developed satellite scheduling module in VieSched++ is used to determine the time periods during which a satellite is observable from a VLBI network. The possible satellite observations are evaluated through the number of stations from which a satellite is observable. Moreover, the impact on determining the orientation of the satellite constellation, caused by the observation geometry, is investigated with using the UT1-UTC Dilution of Precision (UDOP) factor.

Observing extragalactic radio sources is an integral part of Very Long Baseline Interferometry (VLBI) but observing satellites also provides a variety of new possibilities. Interesting scientific applications can be found in providing space ties instead of using local ties for connecting reference frames of different space-geodetic techniques. To generate schedules including observations to satellites a dedicated module has been implemented in the new scheduling software VieSched++. This newly developed module determines possible satellite observations considering several observation conditions, such as the visibility from the selected station network and antenna slew rates. A schedule including observations to quasars and satellites can be generated in a semi-automatic mode. The scheduling of the satellite scans is done manually by the user who can select and adjust the possible satellite observations before adding them to the schedule. The remaining part of the schedule is filled automatically by the software VieSched++ using the general optimization algorithm with observations to quasars. In this poster an overview of the current status of the satellite scheduling module in VieSched++ is given, as well as an outlook to highlight future plans.

Very Long Baseline Interferometry (VLBI) is a space-geodetic technique observing extragalactic radio sources with globally distributed radio telescopes. Over the last years, ideas have been proposed to equip one or more satellites of the second generation of the Galileo constellation with a VLBI transmitter. Observations of satellites with VLBI antennas provide a variety of new possibilities such as the direct determination of the absolute orientation of the satellite orbit with respect to the International Celestial Reference Frame (ICRF) and providing space ties instead of using local ties for connecting reference frames of different space-geodetic techniques. As more VLBI antennas have to observe a source simultaneously, it is necessary to create an observation plan, a so-called schedule. Common scheduling software packages support the scheduling of observations to extragalactic radio sources but only a few are able to schedule observations to satellites. The newly developed scheduling software VieSched++, written in C++, was equipped with a satellite scheduling module which allows the generation of a schedule including both, observations to quasars and satellites. In this work, an overview about the new satellite scheduling module in VieSched++ is given and the different available approaches to schedule satellite observations, the semimanual and the automatic approach, are described. Moreover, this thesis deals with an evaluation study of possible satellite observations to Galileo satellites from a VLBI network. The time periods during which a satellite is observable from the VLBI network are determined using the satellite scheduling module in VieSched++. The possible satellite observations are evaluated through the number of stations from which the satellite could be observed and by the impact on determining the orientation of the satellite constellation directly with respect to ICRF, caused by the observation geometry. The study shows that Galileo satellites exhibit a high visibility for a VLBI network. There are no differences in terms of visibility between the individual orbital planes of the Galileo constellation and between the different orbital positions within these planes. If one satellite would be equipped with a VLBI transmitter there is therefore no preferable plane or slot within a plane to place this satellite. The investigation of the best combination of two satellites equipped with a VLBI transmitter shows that it has to be distinguished if the satellites are within the same plane or in different orbital planes.

Den aktuella studien handlar om att skapa fordjupad forstaelse for hur patienter anslutna till psykosteamet pa vuxenpsykiatrin i Kristianstad upplevelser sitt sammanhang i samarbetet. Studien belyser mer fokuserat hur patienter upplever tillampningen av centrala malsattningar i vardprogrammet, det kontaktskapande behandlingsarbetet, overgangen till ett specialiserat psykosteam ar 2009 och eventuella andra organisatoriska aspekter pa behandlingssituationen samt hur patienter uppfattar att man skulle kunna utveckla verksamheten. Studien realiseras genom en aktionsforskningsstrategi, vilket innebar att forskningsprocessen inbegriper vaxelverkan mellan samtliga deltagare och att studien syftar till att generera praktiskt tillampbar kunskap i den lokala kontexten. Det empiriska materialet bestar av sexton semistrukturerade patientintervjuer. Dessa transkri¬beras och analyseras. I kunskapsprocessen tillampas en terapeutisk utforsknings¬metod och forstaelsen beskrivs som mellanomradeskunskap. Resultatet visar att de intervjuade patienterna upplever att overgangen till psykosteam varit bra for dem. Patienterna har overlag positiva upplevelser av teamets kontaktskapande samarbete och kanner sig delaktiga och hjalpta. Patienterna uppskattar trygghet, kontinuitet och struktur. Av specifika behandlingsinsatser uppskattar patienter sarskilt case management metodiken och samtalskontakt. Anhorigarbete, hembesok och halsobeframjande insatser upplevs som positiva. Manga av patienterna upplever biverkningar av mediciner. Dessa beskrivs som plagsamma, men hanterliga. Brister i verksamheten som patientintervjuerna vittnar om beror patienternas situation i samband med vistelser pa vardavdelningar samt att manga efterfragar ytterligare mojligheter till fordjupade samtalskontakter. Patienternas socioekonomiska situation framtrader som ytterligare ett viktigt utvecklingsomrade.