NAGIOS: RODERIC FUNCIONANDO

Coherence loss in phase-referenced VLBI observations

Repositori DSpace/Manakin

IMPORTANT: Aquest repositori està en una versió antiga des del 3/12/2023. La nova instal.lació está en https://roderic.uv.es/

Coherence loss in phase-referenced VLBI observations

dc.contributor.author	Martí Vidal, Iván
dc.contributor.author	Ros Ibarra, Eduardo
dc.contributor.author	Pérez Torres, Miguel Ángel
dc.contributor.author	Guirado Puerta, Jose Carlos
dc.contributor.author	Jiménez-Monferrer, Sergio
dc.contributor.author	Marcaide Osoro, Juan María
dc.date.accessioned	2011-08-18T12:23:32Z
dc.date.available	2011-08-18T12:23:32Z
dc.date.issued	2010
dc.identifier.citation	Martí-Vidal, I., Ros, E., Pérez-Torres, M. A., Guirado, J. C., Jiménez-Monferrer, S. and Marcaide, J. M. (2010): Coherence loss in phase-referenced VLBI observations, Astronomy and Astrophysics, núm. 515, vol. 7, art. no. 14203	en
dc.identifier.uri	http://hdl.handle.net/10550/20042
dc.description.abstract	Context. Phase-referencing is a standard calibration technique in radio interferometry, particularly suited for the detection of weak sources close to the sensitivity limits of the interferometers. However, effects from a changing atmosphere and inaccuracies in the correlator model may affect the phase-referenced images, and lead to wrong estimates of source flux densities and positions. A systematic observational study of signal decoherence in phase-referencing and its effects in the image plane has not been performed yet. Aims. We systematically studied how the signal coherence in Very-Long-Baseline-Interferometry (VLBI) observations is affected by a phase-reference calibration at different frequencies and for different calibrator-to-target separations. The results obtained should be of interest for a correct interpretation of many phase-referenced observations with VLBI. Methods. We observed a set of 13 strong sources (the S5 polar cap sample) at 8.4 and 15 GHz in phase-reference mode with 32 different calibrator/target combinations spanning angular separations between 1.5 and 20.5 degrees. We obtained phase-referenced images and studied how the dynamic range and peak flux-density depend on observing frequency and source separation. Results. We obtained dynamic ranges and peak flux densities of the phase-referenced images as a function of frequency and separation from the calibrator. We compared our results with models and phenomenological equations previously reported. Conclusions. The dynamic range of the phase-referenced images is strongly limited by the atmosphere at all frequencies and for all source separations. The limiting dynamic range is inversely proportional to the sine of the calibrator-to-target separation. Not surpriseingly, we also find that the peak flux densities decrease with source separation, relative to those obtained from the self- calibrated images.	en
dc.language.iso	en	en
dc.subject	Techniques : interferometric; Atmospheric effects; Instrumentation : interferometers	en
dc.title	Coherence loss in phase-referenced VLBI observations	en
dc.type	journal article	es_ES
dc.subject.unesco	UNESCO::ASTRONOMÍA Y ASTROFÍSICA::Otras especialidades astronómicas	en
dc.identifier.doi	10.1051/0004-6361/201014203	en
dc.identifier.idgrec	055572	en
dc.type.hasVersion	VoR	es_ES
dc.identifier.url	http://www.aanda.org/index.php?option=com_article&access=doi&doi=10.1051/0004-6361/201014203&Itemid=129	en