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 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 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.

Density Wave Related Molecular Cloud Spiral Arms in M51

1987 ◽  
pp. 535-538 ◽  
Author(s):  
G. Rydbeck ◽  
Å. Hjalmarson ◽  
L. E. B. Johansson ◽  
O. E. H. Rydbeck
Keyword(s):  
Molecular Cloud ◽  
Density Wave ◽  
Spiral Arms

Molecular Line Observations at Parkes with a 3 GHz Maser

1979 ◽  
Vol 3 (5) ◽  
pp. 321-323 ◽  
Author(s):  
B. Höglund ◽  
J. B. Whiteoak ◽  
F. F. Gardner
Keyword(s):  
Spectral Line ◽  
Radio Telescope ◽  
Ground State ◽  
State Transitions ◽  
Space Observatory ◽  
Molecular Line ◽  
System Sensitivity ◽  
Onsala Space Observatory

A 3 GHz maser from the Onsala Space Observatory, Sweden, is currently at Parkes on a long-term loan basis. So far, it has been used on the 64-m radio telescope for a two-week period of spectral-line observations in February 1979, providing a system sensitivity far superior to that previously available at the same frequency. The observed lines were the ground-state transitions of CH at 3264, 3335 and 3349 MHz, the 211 – 212 transition of H2CS at 3139 MHz, and the 211-212 transition of CH3CHO at 3195 MHz.

scholarly journals Methods of Correction for the “Wet” Atmosphere in Estimating Baseline Lengths from VLBI

1988 ◽  
Vol 129 ◽  
pp. 543-544
Author(s):  
G. Elgered ◽  
J. L. Davis ◽  
T. A. Herring ◽  
I. I. Shapiro
Keyword(s):  
Water Vapor ◽  
Propagation Delay ◽  
Propagation Path ◽  
Baseline Length ◽  
Space Observatory ◽  
Owens Valley ◽  
Use Of Data ◽  
Onsala Space Observatory ◽  
Vlbi Data ◽  
Water Vapor Radiometer

The error in VLBI estimates of baseline length caused by unmodelled variations in the propagation path through the atmosphere is greater for longer baselines. We present and discuss series of estimates of baseline lengths obtained using different methods to correct for the propagation delay caused by atmospheric water vapor. The main methods are use of data from a water-vapor radiometer (WVR) and Kalman-filtering of the VLBI data themselves to estimate the propagation delay. Since the longest timespan of WVR data associated with geodetic VLBI experiments was obtained at the Onsala Space Observatory in Sweden, we present results for the following three baselines: (1) Onsala–Wettzell, FRG (920 km), (2) Onsala–Haystack/Westford, MA (5600 km), and (3) Onsala–Owens Valley (7914 km).

THE ANALYSIS OF THE STABILITY OF PERMANENT GPS STATION VILNIUS (VLNS) / NUOLAT VEIKIANČIOS VILNIAUS (VLNS) GPS STOTIES STABILUMO ANALIZĖ / АНАЛИЗ СТАБИЛЬНОСТИ ПОСТОЯННО ДЕЙСТВУЮЩЕЙ СТАНЦИИ ГПС VILNIUS (VLNS)

2011 ◽  
Vol 37 (3) ◽  
pp. 129-134 ◽  
Author(s):  
Eimuntas Paršeliūnas ◽  
Ričardas Kolosovskis ◽  
Raimundas Putrimas ◽  
Arūnas Būga
Keyword(s):  
Earth Rotation ◽  
Current Status ◽  
Main Task ◽  
Technical Equipment ◽  
Space Observatory ◽  
International Earth Rotation Service ◽  
Gps Satellites ◽  
Onsala Space Observatory ◽  
The Stability ◽  
Gps Station

Lithuania has been participating in the activities of the EUREF permanent network since 1996, when GPS station VILNIUS started regular continuous tracking of GPS satellites. The GPS station was established with a help of the Onsala Space Observatory (Sweden) and was mounted in the territory of Vilnius international airport (Lithuania). Four character identifier VLNS and DOMES number 10801M001 were assigned to VILNIUS GPS station by the International Earth Rotation Service in 1999. VILNIUS station is operated and maintained by the Institute of Geodesy of Vilnius Technical University. The main task of the permanent VLNS GPS station is to take part in EUREF activities and serve as reference to GPS campaigns in Lithuania. The aim of this paper is to describe the evolution and current status of the technical equipment of VILNIUS station. The paper also presents the analysis of data quality and a few years interval of coordinate determination at VLNS within the EUREF network. Santrauka EUREF nuolat veikiančių stočių tinklo veikloje Lietuva dalyvauja nuo 1996 m., kai GPS VILNIAUS stotis pradėjo reguliarius matavimus iš GPS palydovų. Stotis įsteigta padedant Onsalos kosmoso observatorijai (Švedija). GPS stotis įrengta Vilniaus tarptautinio oro uosto teritorijoje 1999 metais. Tarptautinė žemės sukimositarnyba stočiai suteikė keturių simbolių identifikatorių VLNS ir DOMES numerį 10801M001. GPS VILNIAUS stotį prižiūri ir valdo Vilniaus Gedimino technikos universiteto Geodezijos instituto specialistai. Pagrindinis stoties uždavinys yra dalyvauti EUREF veikloje, ir tai turi būti atraminis geodezinis punktas GPS kampanijoms Lietuvoje. Straipsnio tikslas – aprašyti dabartinę techninės įrangos būklę ir jos tobulinimo eigą. Pateikiama kelerių metų matavimo duomenų kokybės analizė ir nustatytos koordinatės EUREF tinkle. Резюме В проекте сети постоянно действующих станций ГПС EUREF Литва участвует с 1996 г., когда станция VILNIUS стала производить постоянные измерения со спутников ГПС. Станция была основана при помощи Онсольской космической oбсерватории (Швеция). Станция ГПС установлена на территории Вильнюсского международного аэропорта. В 1999 г. Международная служба вращения Земли присвоила станции код VLNS и DOMES номер 10801М001. Станцией управляют специалисты из Геодезического института Вильнюсского технического университета им. Гедиминаса. Главной задачей станции является участие в мероприятиях EUREF, а также быть основным геодезическим пунктом в кампаниях ГПС на территории Литвы. В статье преследовалась цель описать состояние технического оборудования станции и меры по его улучшению. Представлен анализ данных измерений ГПС за несколько лет и определены геодезические координаты в сети EUREF.

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