scholarly journals VGOS Intensives Ishioka-Onsala

2020 ◽  
Author(s):  
Rüdiger Haas ◽  
Eskil Varenius ◽  
Grzegorz Klopotek ◽  
Periklis-Konstantinos Diamantidis ◽  
Saho Matsumoto ◽  
...  
Keyword(s):  
Radio Source ◽  
Radio Telescopes ◽  
Analysis Software ◽  
Space Observatory ◽  
Software Packages ◽  
University Of Technology ◽  
Onsala Space Observatory ◽  
Observation Program ◽  
International Vlbi Service ◽  
Near Future

<p>The VLBI Global Observing System (VGOS) is the VLBI contribution to GGOS. During the last years, several VGOS stations have been established, the VGOS observation program has started, and by 2020 VGOS has achieved an operational state involving eight international VGOS stations. Further VGOS stations are currently installed, so that the number of active VGOS stations will increase drastically in the near future. In the end of 2019 the International VLBI Service for Geodesy and Astrometry (IVS) decided to start a new and so-far experimental VGOS-Intensive series, called VGOS-B, involving Ishioka (Japan) and Onsala (Sweden). Both sites operate modern VGOS stations with 13.2 m diameter radio telescopes, i.e. ISHIOKA (IS) in Japan, and ONSA13NE (OE) and ONSA13SW (OW) in Sweden. In total 12 VGOS-B sessions were planned to be observed between December 2019 and February 2020, one every week, in parallel and simultaneously to legacy S/X INT1 Intensive sessions that involve the stations KOKEE (KK) on Hawaii and WETTZELL (WZ) in Germany. The 1-hour long VGOS-B sessions consist of more than fifty radio source observations, resulting in about 1.6 TB of raw data that are collected at each station. The scheduling of the VGOS-B sessions is done at Vienna University of Technology using <em>VieSched++</em> and the subsequent steps (correlation, fringe-fitting, database creation) are planned to be carried out at the Onsala Space Observatory using <em>DIFX</em> and <em>HOPS</em>. The resulting VGOS databases are planned to be analysed with several VLBI analysis software packages, involving <em>nuSolve</em>, <em>c5++</em> and <em>ivg::ASCOT</em>. In this presentation, we give an overview on the VGOS-B series, present our experiences, and discuss the obtained results.</p>

scholarly journals VGOS Intensives Ishioka-Onsala

2021 ◽  
Author(s):  
Rüdiger Haas ◽  
Eskil Varenius ◽  
Periklis-Konstantinos Diamantidis ◽  
Saho Matsumotu ◽  
Matthias Schartner ◽  
...  
Keyword(s):  
Earth Rotation ◽  
Mean Square ◽  
Radio Telescopes ◽  
Analysis Software ◽  
Space Observatory ◽  
Software Packages ◽  
Onsala Space Observatory ◽  
Observation Program ◽  
International Vlbi Service ◽  
Near Future

<p>The VLBI Global Observing System (VGOS) is the VLBI contribution to GGOS. During the last years, several VGOS stations have been established, the VGOS observation program has started, and by 2021 VGOS has achieved an operational state involving nine international VGOS stations. Further VGOS stations are currently being installed, so that the number of active VGOS stations will increase drastically in the near future. In the end of 2019 the International VLBI Service for Geodesy and Astrometry (IVS) decided to start a new and so-far experimental VGOS-Intensive series, called VGOS-B, involving Ishioka (Japan) and Onsala (Sweden). Both sites operate modern VGOS stations with 13.2~m diameter radio telescopes, i.e. ISHIOKA (IS) in Japan, and ONSA13NE (OE) and ONSA13SW (OW) in Sweden. In total 12 VGOS-B sessions were observed between December 2019 and February 2020, one every week, in parallel and simultaneously to legacy S/X INT1 Intensive sessions that involve the stations KOKEE (KK) on Hawaii and WETTZELL (WZ) in Germany. These 1-hour long VGOS-B sessions consist of more than fifty radio source observations, resulting in about 1.6 TB of raw data that are collected at each station. The scheduling of the VGOS-B sessions was done using <em>VieSched++</em> and the subsequent steps (correlation, fringe-fitting, database creation) were carried out at the Onsala Space Observatory using <em>DIFX</em> and <em>HOPS</em>. The resulting VGOS databases were  analysed with several VLBI analysis software packages, involving <em>nuSolve</em>, <em>c5++</em> and <em>ASCOT</em>. In this presentation, we give an overview on the VGOS-B series, present our experiences, and discuss the obtained results. The derived UT1-UTC results were compared to corresponding results from standard legacy S/X Intensive sessions (INT1/INT2), as well to the final values of the International Earth Rotation and Reference Frame Service (IERS), provided in IERS Bulletin~B. <br>The VGOS-B series achieve 3-4 times lower formal uncertainties for the UT1-UTC results than standard legacy S/X INT series.  Furthermore, the root mean square (RMS) agreement with respect to the IERS Bulletin B is 30-40 % better for the VGOS-B results than for the INT1/INT2 results.</p>

Short-baseline interferometry at Onsala Space Observatory

2021 ◽  
Author(s):  
Eskil Varenius ◽  
Rüdiger Haas ◽  
Periklis Diamantidis ◽  
Tobias Nilsson
Keyword(s):  
Mixed Mode ◽  
Reference Frames ◽  
Radio Telescopes ◽  
Space Observatory ◽  
Short Baseline ◽  
Geodetic Vlbi ◽  
Onsala Space Observatory ◽  
X Band ◽  
The Impact ◽  
Local Tie

<p>A growing number of geodetic VLBI stations participate in the VLBI Global Observing System (VGOS). Multiple sites operate both new VGOS telescopes and legacy S/X VLBI telescopes. At Onsala Space Observatory, Sweden, we operate two 13.2 m diameter VGOS radio telescopes, ONSA13NE (OE) and ONSA13SW (OW), as well as the 20~m legacy S/X telescope ONSALA60 (ON). Transitioning from the legacy system and providing continuity of the terrestrial and celestial reference frames necessitate establishing ties between S/X and VGOS telescopes. Since spring 2019, we have carried out more than 20 short-baseline (550 m) interferometric observations at X-band to establish local-tie vectors between ON, OE and OW. The obtained data were correlated at Onsala Space Observatory using DiFX, post-processed using HOPS and analysed with nuSolve and ASCOT. In this presentation we given an overview of the observations, analysis, and results of these local-tie experiments. We investigate the impact of modeling e.g. gravitational deformation, and the possibility of using phase-delays to improve the precision. Finally, we present a comparison with preliminary results from two other methods: global mixed-mode observations and classical local-tie measurements.</p>

scholarly journals Short-baseline interferometry local-tie experiments at the Onsala Space Observatory

2021 ◽  
Vol 95 (5) ◽  
Author(s):  
Eskil Varenius ◽  
Rüdiger Haas ◽  
Tobias Nilsson
Keyword(s):  
Very Long Baseline Interferometry ◽  
A Priori ◽  
Radio Telescopes ◽  
Space Observatory ◽  
Short Baseline ◽  
Long Baseline ◽  
Onsala Space Observatory ◽  
X Band ◽  
Group Delays ◽  
Local Tie

AbstractWe present results from observation, correlation and analysis of interferometric measurements between the three geodetic very long baseline interferometry (VLBI) stations at the Onsala Space Observatory. In total, 25 sessions were observed in 2019 and 2020, most of them 24 h long, all using X band only. These involved the legacy VLBI station ONSALA60 and the Onsala twin telescopes, ONSA13NE and ONSA13SW, two broadband stations for the next-generation geodetic VLBI global observing system (VGOS). We used two analysis packages: $$\nu $$ ν Solve to pre-process the data and solve ambiguities, and ASCOT to solve for station positions, including modelling gravitational deformation of the radio telescopes and other significant effects. We obtained weighted root mean square post-fit residuals for each session on the order of 10–15 ps using group-delays and 2–5 ps using phase-delays. The best performance was achieved on the (rather short) baseline between the VGOS stations. As the main result of this work, we determined the coordinates of the Onsala twin telescopes in VTRF2020b with sub-millimetre precision. This new set of coordinates should be used from now on for scheduling, correlation, as a priori for data analyses, and for comparison with classical local-tie techniques. Finally, we find that positions estimated from phase-delays are offset $$\sim +3$$ ∼ + 3  mm in the up-component with respect to group-delays. Additional modelling of (elevation dependent) effects may contribute to the future understanding of this offset.

scholarly journals Molecular Cloud Spiral Arms and Results from Tidal Interaction Modeling

1989 ◽  
Vol 8 ◽  
pp. 579-580
Author(s):  
Åke Hjalmarson
Keyword(s):  
Molecular Cloud ◽  
Theoretical Physics ◽  
Space Observatory ◽  
Spiral Arms ◽  
Tidal Interaction ◽  
University Of Technology ◽  
Onsala Space Observatory ◽  
Interaction Modeling

I wish to report on some results from mapping of molecular cloud distributions in galaxies and from tidal interaction modeling – work performed at Onsala Space Observatory and in the Astrophysics Group of Institute of Theoretical Physics, Chalmers University of Technology/University of Göteborg.

scholarly journals Sensing atmospheric structure: Tropospheric tomographic results of the small-scale GPS campaign at the Onsala Space Observatory

2000 ◽  
Vol 52 (11) ◽  
pp. 941-945 ◽  
Author(s):  
A. Flores ◽  
L. P. Gradinarsky ◽  
P. Elósegui ◽  
G. Elgered ◽  
J. L. Davis ◽  
...  
Keyword(s):  
Small Scale ◽  
Space Observatory ◽  
Atmospheric Structure ◽  
Onsala Space Observatory

scholarly journals Observing UT1-UTC with VGOS

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Rüdiger Haas ◽  
Eskil Varenius ◽  
Saho Matsumoto ◽  
Matthias Schartner
Keyword(s):  
Standard Deviation ◽  
Reference Frame ◽  
Earth Rotation ◽  
Space Observatory ◽  
International Earth Rotation ◽  
Onsala Space Observatory ◽  
X Band ◽  
First Results

AbstractWe present first results for the determination of UT1-UTC using the VLBI Global Observing System (VGOS). During December 2019 through February 2020, a series of 1 h long observing sessions were performed using the VGOS stations at Ishioka in Japan and the Onsala twin telescopes in Sweden. These VGOS-B sessions were observed simultaneously to standard legacy S/X-band Intensive sessions. The VGOS-B data were correlated, post-correlation processed, and analysed at the Onsala Space Observatory. The derived UT1-UTC results were compared to corresponding results from standard legacy S/X-band Intensive sessions (INT1/INT2), as well as to the final values of the International Earth Rotation and Reference Frame Service (IERS), provided in IERS Bulletin B. The VGOS-B series achieves 3–4 times lower formal uncertainties for the UT1-UTC results than standard legacy S/X-band INT series. The RMS agreement w.r.t. to IERS Bulletin B is slightly better for the VGOS-B results than for the simultaneously observed legacy S/X-band INT1 results, and the VGOS-B results have a small bias only with the smallest remaining standard deviation.

3.3 GHz Ground-State Transitions of CH towards Southern HII Regions–1. An Atlas of CH Profiles

1985 ◽  
Vol 6 (1) ◽  
pp. 6-33 ◽  
Author(s):  
J. B. Whiteoak ◽  
F. F. Gardner ◽  
Gwenyth A. Manefield ◽  
B. Höglund ◽  
L. E. B. Johansson
Keyword(s):  
Radio Telescope ◽  
Ground State ◽  
Hii Regions ◽  
State Transitions ◽  
Space Observatory ◽  
Onsala Space Observatory

SummaryThe Parkes 64-m radio telescope equipped with a 3 GHz maser on loan from the Onsala Space Observatory has been used to observe the three ground-state transitions of CH (at 3264, 3335 and 3349 MHz) towards a total of 74 HII regions, mostly at southern declinations. In this paper the regions and related characteristics are listed, and the CH spectra displayed.

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