High precision difference astrometry applied to the triplet of S 5 radio sources BL 1803 + 784 / QSO 1928 + 738 / BL 2007 + 777

High precision difference astrometry applied to the triplet of S 5 radio sources B 1803 + 784 / Q 1928 + 738 / B 2007 + 777

ASTRONOMY AND ASTROPHYSICS High precision difference astrometry applied to the triplet of S5 radio sources B1803+784/Q1928+738/B2007+777 Abstract. We determined the separations of the radio sources in the triangle formed by the BL Lac objects 1803+784 and 2007+777, and the QSO 1928+738 from in-tercontinental interferometric observations carried out in November 1991 at the frequencies of 2.3 and...

On the way to global phase-delay astrometry

The use of the phase-delay improves substantially the accuracy obtained in VLBI astrometry with respect to the group-delay observable. Recently, Ros et al. (1999) have extended the related phase-connection technique to a triangle of radio sources with relative separations up to 6.8◦ (the S5 sources BL 1803+784/QSO 1928+738/BL 2007+777). This technique has also been extended for separations up t...

Letter to the Editor VLBI difference astrometry at 43 GHz

From 43 GHz VLBA observations of the pair of radio sources QSO 1928+738 and BL 2007+777 we have demonstrated the feasibility of precision phase-delay differential astrometric techniques at millimeter wavelengths. For a pair of sources with 5◦ separation and high antenna elevations, we have shown that present astrometric models and millimeter arrays are advanced enough to model the differential ...

High Precision Astrometry with Vlbi: from the Triangle 1803+784/1928+738/2007+777 to the Complete S5 Polar Cap Sample

Towards global phase-delay VLBI astrometry: Observations of QSO1150+812 and BL1803+784

On 18 November 1993, we observed the QSO 1150+812 and the BL Lac object 1803+784, nearly 15 apart on the sky, with a VLBI array, simultaneously recording at 8.4 and 2.3 GHz. Using difference astrometry techniques, we determined the coordinates of 1803+784 relative to those of 1150+812 to be ∆α = 6 7 33. 18469± 0. 00020 ∆δ = −2 30′ 25. 13557± 0. 00075 These standard errors contain estimated cont...