Related papers: Is there a standard measuring rod in the Universe?
Systematic surveys of astronomical objects often lead to discoveries, but always provide invaluable information for statistical studies of well-defined samples. They also promote follow-up investigations of individual objects or classes.…
Very Long Baseline Interferometry (VLBI) observations can provide the position of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object…
Very long baseline interferometry (VLBI) is a technique for imaging celestial radio emissions by simultaneously observing a source from telescopes distributed across Earth. The challenges in reconstructing images from fine angular…
We present results from a large global VLBI(Very Long Baseline Interferometry) survey of compact radio sources at 86 GHz which started in October 2001. The main goal of the survey is to increase the total number of objects accessible for…
Astrometry at centimeter wavelengths using Very Long Baseline Interferometry is approaching accuracies of ~1 uas for the angle between a target and a calibrator source separated by <1 degree on the sky. The BeSSeL Survey and the Japanese…
Very long baseline interferometry (VLBI) astrometry is used to determine the three-dimensional position and proper motion of astronomical objects. A typical VLBI astrometric campaign generally includes around ten observations, making it…
Less than $200$ radio-loud active galactic nuclei (AGN) are known above redshift $4$. Around $40$ of them have been observed at milliarcsecond (mas) scale resolution with very long baseline interferometry (VLBI) technique. Some of them are…
Very Long Baseline Interferometry (VLBI) observations can provide the position of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object…
A space-based very long baseline interferometry (VLBI) programme, named as the Cosmic Microscope, is proposed to involve dual VLBI telescopes in the space working together with giant ground-based telescopes (e.g., Square Kilometre Array,…
Space Very Long Baseline Interferometry is a radio astronomy technique distinguished by a record-high angular resolution reaching single-digit microseconds of arc. The paper provides a brief account of the history of developments of this…
For Very Long Baseline Interferometry (VLBI), the fringe spacing is extremely narrow compared to the field of view imposed by the primary beam of each element. This means that an extremely large number of resolution units can potentially be…
In this paper, we use multi-frequency angular size measurements of 58 intermediate-luminosity quasars reaching the redshifts $z\sim 3$ and demonstrate that they can be used as standard rulers for cosmological inference. Our results indicate…
We report on the first wide-field, very long baseline interferometry (VLBI) survey at 90 cm. The survey area consists of two overlapping 28 deg^2 fields centred on the quasar J0226+3421 and the gravitational lens B0218+357. A total of 618…
A review is given on the current status and selected results from large VLBI surveys of compact extragalactic radio sources made between 13 cm and 3 mm wavelengths and covering the entire sky. More than 4200 objects are observed and imaged…
VLBI at millimeter wavelengths (mm-VLBI) allows the detailed imaging of compact galactic and extragalactic radio sources with micro-arcsecond scale resolution, unaccessible by other observing techniques. Here we discuss the scientific…
We present a milliarcsecond-resolution radio survey of 17 high-redshift (4 < z < 5.4) blazar candidates observed with the European Very Long Baseline Interferometry (VLBI) Network at 5 GHz. The primary objective of this study was to…
Very long baseline interferometry (VLBI) technique allows us to determine positions of thousands of radio sources using the absolute astrometry approach. I have investigated the impact of a selection of observing frequencies in a range from…
Finding a suitable very long baseline (VLBI) interferometer geometry is a key task in planning observations, especially imaging sessions. The main characteristic of the quality of VLBI imaging data is the (u, v)-coverage. In the case when…
When comparing modern fundamental reference frames in the radio (International Celestial Reference Frame) and optical (Gaia), a couple of bright radio reference sources appear to have very large radio-optical offsets, from tens up to…
The next generation of very long baseline interferometry (VLBI) is stepping into the era of microarcsecond ($\mu$as) astronomy, and pushing astronomy, especially astrometry, to new heights. VLBI with the Square Kilometre Array (SKA),…