scholarly journals Recent Results of Radio Interferometric Determinations of a Transcontinental Baseline, Polar Motion, and Earth Rotation

1979 ◽  
Vol 82 ◽  
pp. 217-224 ◽  
Author(s):  
D. S. Robertson ◽  
W. E. Carter ◽  
B. E. Corey ◽  
W. D. Cotton ◽  
C. C. Counselman ◽  
...  
Keyword(s):  
Polar Motion ◽  
Pole Position ◽  
Baseline Length ◽  
Radio Sources ◽  
Mean Square ◽  
A Posteriori ◽  
Weighted Mean ◽  
Owens Valley ◽  
Radio Observatory ◽  
International Polar

Radio interferometric observations of extragalactic radio sources have been made with antennas at the Haystack Observatory in Massachusetts and the Owens Valley Radio Observatory in California during fourteen separate experiments distributed between September 1976 and May 1978. The components of the baseline vector and the coordinates of the sources were estimated from the data from each experiment separately. The root-weighted-mean-square scatter about the weighted mean (“repeatability”) of the estimates of the length of the 3900 km baseline was approximately 7 cm, and of the source coordinates, approximatelyor less, except for the declinations of low-declination sources. With the source coordinates all held fixed at the best available,a posteriori, values, and the analyses repeated for each experiment, the repeatability obtained for the estimate of baseline length was 4 cm. From analyses of the data from several experiments simultaneously, estimates were obtained of changes in the x component of pole position and in the Earth's rotation (UT1). Comparison with the corresponding results obtained by the Bureau International de l'Heure (BIH) discloses systematic differences. In particular, the trends in the radio interferometric determinations of the changes in pole position agree more closely with those from the International Polar Motion Service (IPMS) and from the Doppler observations of satellites than with those from the BIH.

Hohenheimer Inventar zum Politikwissen (HIP)

Diagnostica ◽  
2017 ◽  
Vol 63 (3) ◽  
pp. 206-218 ◽  
Author(s):  
Sabine Trepte ◽  
Laura Loy ◽  
Josephine B. Schmitt ◽  
Siegmar Otto
Keyword(s):  
Mean Square ◽  
A Posteriori ◽  
Weighted Mean ◽  
Plausible Values

Zusammenfassung. Politisches Wissen der Bürgerinnen und Bürger gilt als wesentlich für die Handlungsfähigkeit einer Demokratie und wird intensiv erforscht. Derzeit liegt jedoch kein Messinstrument vor, das theoretisch hergeleitet relevante Dimensionen des politischen Wissens diagnostiziert und frei für Forschungszwecke verfügbar ist. Wir entwickelten daher auf Basis des Rasch-Modells das Hohenheimer Inventar zum Politikwissen (HIP) mit den Dimensionen a) Grundlagen (staatliche Strukturen und historische Fakten) und b) Aktuelles (Themen und Akteure aus verschiedenen Politikfeldern). In einer deutschlandweiten Online-Befragung (N = 1 082) ergaben sich zufriedenstellende weighted-mean-square (WMNSQ)-infit-Werte der 85 Items (0.82 ≤ x ≤ 1.24) und eine expected-a-posteriori/plausible-values (EAP/PV)-Reliabilität von .92 für das eindimensionale Modell und von jeweils .91 für beide Dimensionen. Eine Validierung der Skala zeigte, dass die Personenwerte mit politischem Interesse, politischer Partizipation, politischer Informationsnutzung (Kriteriumsvalidierung) sowie dem subjektiven Wissen der Befragten (konvergente Konstruktvalidierung) zusammenhingen. Wir diskutieren die Herausforderung, die Dimension Aktuelles an sich verändernde politische Gegebenheiten anzupassen, sowie weitere Schritte der Skalenvalidierung.

OBSERVATIONS OF THE OWENS VALLEY RADIO OBSERVATORY, 5. ACCURATE RIGHT ASCENSIONS FOR 227 RADIO SOURCES

1964 ◽  
Author(s):  
E. B. Fomalont ◽  
T. A. Matthews ◽  
D. Morris ◽  
J. D. Wyndham
Keyword(s):  
Radio Sources ◽  
Owens Valley ◽  
Radio Observatory

scholarly journals The road to quasars

2014 ◽  
Vol 10 (S313) ◽  
pp. 190-195 ◽  
Author(s):  
K. I. Kellermann
Keyword(s):  
Radio Source ◽  
Optical Measurements ◽  
Radio Sources ◽  
Optical Counterpart ◽  
Owens Valley ◽  
True Nature ◽  
Radio Observatory ◽  
The Road ◽  
Lunar Occultation ◽  
Faint Galaxy

AbstractAlthough the extragalactic nature of 3C 48 and other quasi stellar radio sources was discussed as early as 1960 by John Bolton and others, it was rejected largely because of preconceived ideas about what appeared to be unrealistically high radio and optical luminosities. Not until the 1962 occultations of the strong radio source 3C 273 at Parkes, which led Maarten Schmidt to identify 3C 273 with an apparent stellar object at a redshift of 0.16, was the true nature understood. Successive radio and optical measurements quickly led to the identification of other quasars with increasingly large redshifts and the general, although for some decades not universal, acceptance of quasars as the very luminous nuclei of galaxies.Curiously, 3C 273, which is one of the strongest extragalactic sources in the sky, was first cataloged in 1959 and the magnitude 13 optical counterpart was observed at least as early as 1887. Since 1960, much fainter optical counterparts were being routinely identified using accurate radio interferometer positions which were measured primarily at the Caltech Owens Valley Radio Observatory. However, 3C 273 eluded identification until the series of lunar occultation observations led by Cyril Hazard. Although an accurate radio position had been obtained earlier with the OVRO interferometer, inexplicably 3C 273 was initially misidentified with a faint galaxy located about an arc minute away from the true quasar position.

Practical Realization of a Reference System for Earth Dynamics by Satellite Methods

1975 ◽  
Vol 26 ◽  
pp. 341-380 ◽  
Author(s):  
R. J. Anderle ◽  
M. C. Tanenbaum
Keyword(s):  
Reference Frame ◽  
Polar Motion ◽  
Pole Position ◽  
Control Points ◽  
Significant Information ◽  
Crustal Motion ◽  
Average Reference ◽  
Future Data ◽  
Existing Data

AbstractObservations of artificial earth satellites provide a means of establishing an.origin, orientation, scale and control points for a coordinate system. Neither existing data nor future data are likely to provide significant information on the .001 angle between the axis of angular momentum and axis of rotation. Existing data have provided data to about .01 accuracy on the pole position and to possibly a meter on the origin of the system and for control points. The longitude origin is essentially arbitrary. While these accuracies permit acquisition of useful data on tides and polar motion through dynamio analyses, they are inadequate for determination of crustal motion or significant improvement in polar motion. The limitations arise from gravity, drag and radiation forces on the satellites as well as from instrument errors. Improvements in laser equipment and the launch of the dense LAGEOS satellite in an orbit high enough to suppress significant gravity and drag errors will permit determination of crustal motion and more accurate, higher frequency, polar motion. However, the reference frame for the results is likely to be an average reference frame defined by the observing stations, resulting in significant corrections to be determined for effects of changes in station configuration and data losses.

Indikatoren schulischen Wohlbefindens bei gesunden und chronisch kranken Kindern: Psychometrische Prüfung und Validierung adaptierter FEESS-Skalen

2020 ◽  
Vol 34 (3-4) ◽  
pp. 201-219
Author(s):  
Kathleen Schnick-Vollmer ◽  
Christiane Diefenbach ◽  
Christine Gräf ◽  
Dorle Hoffmann ◽  
Isabell Hoffmann ◽  
...  
Keyword(s):  
Item Response ◽  
Mean Square ◽  
Weighted Mean ◽  
Externe Validität ◽  
Chronisch Kranke

Zusammenfassung. Das schulbezogene Wohlbefinden (SBWB) ist eine wichtige Voraussetzung für schulischen Erfolg. Trotzdem existieren – insbesondere mit Blick auf die Erfassung des SBWB von Erstklässlern – im deutschsprachigen Raum nur vereinzelt Studien. Dies lässt sich möglicherweise durch das Fehlen geeigneter Instrumente begründen. Dies gilt auch und insbesondere dann, wenn der Gesundheitszustand der Kinder berücksichtigt werden soll. Das Ziel der vorliegenden Arbeit besteht in der Validierung des adaptierten Fragebogens zur Erfassung von emotionalen und sozialen Schulerfahrungen (FEESS 1 – 2; Rauer & Schuck, 2004 ) mit Fokus auf die Eignung des Instruments für chronisch kranke und gesunde Kinder. Dafür wird zunächst das Konstrukt Wohlbefinden (WB) resp. SBWB definiert und in einschlägige Theorien – die Selbstbestimmungstheorie nach Deci und Ryan (1985) und das Erwartung-mal-Wert-Modell nach Wigfield und Eccles (2000) – eingebettet. Die Bedeutung der verwendeten FEESS-Skalen und ihr Zusammenhang zum schulischen Erfolg werden aufgezeigt. 1491 Kinder wurden zu ihrer Lernfreude (LF), sozialen Integration (SI) und zu ihrem schulbezogenen Fähigkeitsselbstkonzept (SK) befragt. Die Erfassung des Gesundheitszustands wurde über Elternfragebögen und Schuleingangsuntersuchungen eruiert. Zudem wurden die Eltern zur gesundheitsbezogenen Lebensqualität (LQ) ihrer Kinder mit Hilfe eines Fragebogens zur Erfassung der Lebensqualität von Kindern (KINDL; Bullinger, Mackensen & Kirchberger, 1994 ) befragt. Die psychometrische Qualität der adaptierten FEESS-Skalen wurde für beide Gruppen (erkrankt / gesund) auf Skalen- und Itemebene untersucht. Hierzu kamen sowohl klassische Verfahren als auch Verfahren der Item-Response-Theorie zum Einsatz. Die Ergebnisse untermauern die Validität des Konstruktes SBWB und stützen die Annahme der Dreidimensionalität (LF, SI, SK). Alle drei Skalen zeigen eine zufriedenstellende bis sehr gute Reliabilität. Die Items zeigen sehr gute MNSQ-Werte (weighted mean-square; gewichtete Abweichungsquadrate) und geeignete Trennschärfen. Die externe Validität, für deren Berechnung der Zusammenhang zwischen den Angaben der Kinder und den Angaben der Eltern zur gesundheitsbezogenen LQ untersucht wurde, konnte noch nicht ausreichend nachgewiesen werden. Bis auf diese Einschränkung kann mit Hilfe der adaptierten FEESS-Skalen im nächsten Schritt das SBWB von gesunden und erkrankten Kindern verglichen werden, um mögliche Chancenungleichheiten auszugleichen.

The Dynamics of Atmospherically Driven Intraseasonal Polar Motion

2008 ◽  
Vol 65 (7) ◽  
pp. 2290-2307 ◽  
Author(s):  
Steven B. Feldstein
Keyword(s):  
Excitation Function ◽  
Normal Mode ◽  
Polar Motion ◽  
Stationary Wave ◽  
Pole Position ◽  
Heat Fluxes ◽  
Synoptic Scale ◽  
Zonal Wavenumber ◽  
Polar Motion Excitation ◽  
Winter Hemisphere

Abstract The atmospheric dynamical processes that drive intraseasonal polar motion are examined with National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data and with pole position data from the International Earth Rotation Service. The primary methodology involves the regression of different atmospheric variables against the polar motion excitation function. A power spectral analysis of the polar motion excitation function finds a statistically significant peak at 10 days. Correlation calculations show that this peak is associated with the 10-day, first antisymmetric, zonal wavenumber 1, normal mode of the atmosphere. A coherency calculation indicates that the atmospheric driving of polar motion is mostly confined to two frequency bands, with periods of 7.5–13 and 13–90 days. Regressions of surface pressure reveal that the 7.5–13-day band corresponds to the 10-day atmospheric normal mode and the 13–90-day band to a quasi-stationary wave. The regressions of pole position and the various torques indicate not only that the equatorial bulge torque dominates the mountain and friction torques but also that the driving by the equatorial bulge torque accounts for a substantial fraction of the intraseasonal polar motion. Furthermore, although the 10-day and quasi-stationary wave contributions to the equatorial bulge torque are similar, the response in the pole position is primarily due to the quasi-stationary wave. Additional calculations of regressed power spectra and meridional heat fluxes indicate that the atmospheric wave pattern that drives polar motion is itself excited by synoptic-scale eddies. Regressions of pole position with separate torques from either hemisphere show that most of the pole displacement arises from the equatorial bulge torque from the winter hemisphere. Together with the above findings on wave–wave interactions, these results suggest that synoptic-scale eddies in the winter hemisphere excite the quasi-stationary wave, which in turn drives the polar motion through the equatorial bulge torque.

scholarly journals VLBI Measurements of Radio Source Positions at Three U.S. Stations

1981 ◽  
Vol 63 ◽  
pp. 329-336
Author(s):  
Shu-Hua Ye
Keyword(s):  
Radio Source ◽  
Radio Astronomy ◽  
Data Reduction ◽  
Geodetic Survey ◽  
Time Span ◽  
National Geodetic Survey ◽  
Owens Valley ◽  
Radio Observatory ◽  
The U.S

AbstractResults of VLBI measurement of 14 radio source positions at three U.S. stations during the MERIT short campaign is presented. Comparisons with other solutions are given, together with the comparisons between several radio source catalogues.During the MERIT short campaign, several observatories cooperated in VLBI measurements organized jointly by the U.S. National Geodetic Survey (NGS) and the National Aeronautics and Space Administration (NASA). There were two 7-day observations arranged from Sept. 26 to Oct. 2 and from Oct. 16 to Oct. 22, with time span nearly 23 hours per day. Details of the observation and data reduction have been published elsewhere (1). This paper deals with radio source positions determined by three U.S. stations, the Haystack Observatory, the Harvard Radio Astronomy Station (HRAS) and the Owens Valley Radio Observatory (OVRO).

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