| 1. |
- Bartel, N., et al.
(author)
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The Compact Radio Source 2021+614 : Simultaneous 2.3 and 8.3 GHz Mark III VLBI Observations
- 1984
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In: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 279:1, s. 116-121
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Journal article (peer-reviewed)abstract
- Second-epoch VLBI observations of the flat-spectrum radio source 2021+614 made simultaneously at 2.3 and 8.3 GHz with the Mark III system are reported. The maps derived from these observations reveal a complex, frequency-dependent radio structure on the milliarcsecond scale. The object has four nearly collinear components oriented at a position angle of about 35 degrees and embedded in an extended region. Two of these are optically thin, one has a flat spectrum, and the other appears to be synchrotron self-absorbed in the frequency range 2.3-8.3 GHz. No significant structural variation is found at either frequency between epochs separated by about three years. The formal estimate of the transverse velocity between two components, one with a flat and the other with an inverted spectrum, is v/c = 0.7 + or - 2.3. Remarkable similarities between 2021+614 and the unusual source 0316+413 are discussed.
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| 2. |
- Bååth, L.B. 1948-, et al.
(author)
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The Radio Fine Structure of the BL Lacertae Objects AO0235+164, 0735+178, BL Lac, 1749+701, Mk 421 and 3C 66 A at 5 GHz
- 1981
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In: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 96:1-2, s. 316-324
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Journal article (peer-reviewed)abstract
- Very long baseline interferometer observations at 4997 MHz (lambda = 6 cm) on European and intercontinental baselines with lengths up to 1.35 108lambda have been used to probe the milliarc s structure of the BL Lacertae objects AO 0235+164, 0735+178, BL Lac, 1749+701, Mk 421, and 3C 66A. Two sets of observations are reported, made in November 1978 and March 1979. AO 0235+164 and 0735+178 both showed structures consisting of a very bright, unresolved core and a jet-like component extending ˜5".4 10-3 along position angle ˜20° and ˜4".2 10-3 along position angle ˜45°, respectively. AO 0235+164 contained more than 98% of the total flux density within a diameter of ≲ 36" 10-3. BL Lac, 1749+701 and Mk 421 all showed evidence for a complex structure of several components, including an unresolved core. 3 C 66A was elongated along position angle ˜ -45°.
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| 3. |
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| 4. |
- Matveenko, L. I., et al.
(author)
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The structure of the quasar 3C-345
- 1992
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In: Soviet Astronomy Letters. - Moscow : Rossijskaja akademija nauk / Russian Academy of Sciences. - 0320-0108. ; 18:6, s. 379-391
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Journal article (peer-reviewed)abstract
- We study the fine structure of the quasar 3C 345 at a wavelength of 49 cm. The apparent size of the core and low-frequency variability are due to the opacity of the surrounding ionized medium and the electron density distribution. We find the distance dependence of the size and brightness temperature of the components. Relativistic plasma is being ejected into a cone, with vertex angle approximately 40-degrees in position -110-degrees. The jet consists of narrow twisted filaments.
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| 5. |
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| 6. |
- Standke, K. J., et al.
(author)
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High Sensitivity VLBI at 86 GHz : First Fringes with the 100 m Radio Telescope at Effelsberg
- 1993
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In: VLBI Technology. - Tokyo : Terra Scientific. - 4887041128 ; , s. 75-85
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Book chapter (peer-reviewed)abstract
- Inclusion of large and sensitive antennas is of essential importance to further improve the imaging capabilities of VLBI at 3.5 mm wavelength. The combination of the 100 m radio telescope at Effelsberg (illuminated diameter ~60 m at lambda = 3.5 mm) with the 30 m radio telescope at Pico Veleta presently allows the detection of compact flux down to a level of 0.2 Jy (for τ=360 seconds integration time). Fringes have been found for 23 radio sources many of them not observed previously with VLBI at 86 GHz. On European baselines to Effelsberg the SNR typically was 10 to 30 (and ranged up to 107 for 3C279), facilitating model fitting for the brightest sources. Even in spite of chaning weather conditions during the observations (coherence times ranged between 10 to 100 seconds) and a still non-optimum pointing model for the 100 m antenna for observations at high frequencies, these results demonstrate that the 100 m radio telescope can be successfully incorporated in global VLBI experiments at 3.5 mm wavelength.
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