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 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.

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.

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).

scholarly journals The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars

2019 ◽  
Vol 489 (4) ◽  
pp. 5365-5380 ◽  
Author(s):  
J Y Koay ◽  
D L Jauncey ◽  
T Hovatta ◽  
S Kiehlmann ◽  
H E Bignall ◽  
...  
Keyword(s):  
Flux Density ◽  
High Energy ◽  
Short Term ◽  
Owens Valley ◽  
Hot Stars ◽  
Radio Observatory ◽  
Interstellar Scintillation ◽  
The Galaxy ◽  
Rare Class

ABSTRACT We have conducted the first systematic search for interday variability in a large sample of extragalactic radio sources at 15 GHz. From the sample of 1158 radio-selected blazars monitored over an ∼10 yr span by the Owens Valley Radio Observatory 40-m telescope, we identified 20 sources exhibiting significant flux density variations on 4-d time-scales. The sky distribution of the variable sources is strongly dependent on the line-of-sight Galactic H α intensities from the Wisconsin H α Mapper Survey, demonstrating the contribution of interstellar scintillation (ISS) to their interday variability. 21 per cent of sources observed through sightlines with H α intensities larger than 10  rayleighs exhibit significant ISS persistent over the ∼10 yr period. The fraction of scintillators is potentially larger when considering less significant variables missed by our selection criteria, due to ISS intermittency. This study demonstrates that ISS is still important at 15 GHz, particularly through strongly scattered sightlines of the Galaxy. Of the 20 most significant variables, 11 are observed through the Orion–Eridanus superbubble, photoionized by hot stars of the Orion OB1 association. The high-energy neutrino source TXS 0506+056 is observed through this region, so ISS must be considered in any interpretation of its short-term radio variability. J0616−1041 appears to exhibit large ∼20 per cent interday flux density variations, comparable in magnitude to that of the very rare class of extreme, intrahour scintillators that includes PKS0405−385, J1819+3845, and PKS1257−326; this needs to be confirmed by higher cadence follow-up observations.

scholarly journals VSOP, A Space VLBI Programme

1990 ◽  
Vol 123 ◽  
pp. 263-269
Author(s):  
H. Hirabayashi
Keyword(s):  
Active Galactic Nuclei ◽  
Phase Transfer ◽  
Galactic Nuclei ◽  
Satellite Orbit ◽  
Radio Sources ◽  
Space Observatory ◽  
Stellar Objects ◽  
Radio Observatory ◽  
Star Forming ◽  
Star Forming Regions

AbstractVSOP, VLBI Space Observatory Programme, is an approved space VLBI programme of ISAS for the study of very compact radio sources with the synthesized aperture of 30,000 km diameter, by connecting an orbiting radio observatory with ground radiotelescopes. The VSOP satellite carrying 10 m antenna with 1.6, 5, and 22 GHz band receivers will be launched in early 1995 by M-V rocket of ISAS into an eccentric orbit with 20,000 km in apogee height. The tracking network will be formed for the satellite orbit determination, phase transfer and IF down-link. VSOP aims imaging capability with best resolution of 0.0001 arc second in 22 GHz band. Imaging of active galactic nuclei, star forming regions and stellar objects, and radioastrometry are main scientific targets.

scholarly journals An Upper Limit to the Intrinsic Anisotropy of the Microwave Background Radiation on a Scale of 7 Arc Minutes

1988 ◽  
Vol 130 ◽  
pp. 37-41
Author(s):  
A. C. S. Readhead ◽  
C. R. Lawrence ◽  
S. T. Myers ◽  
W. L. W. Sargent
Keyword(s):  
Background Radiation ◽  
Microwave Background ◽  
Owens Valley ◽  
Radio Observatory ◽  
Upper Limit ◽  
Microwave Background Radiation ◽  
Intrinsic Anisotropy

For the last four years we have been engaged on a program to look for intrinsic variations in the Microwave Background Radiation (MBR) at the Owens Valley Radio Observatory (OVRO). We summarize here the results of this continuing search.

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