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We report on the results of multi-epoch VLBI observations with VERA (VLBI Exploration of Radio Astrometry) of the 22 GHz H2O masers associated with the young stellar object SVS 13 in the NGC 1333 region. We have carried out…

We present the results of phase-referenced VLBA+Effelsberg observations at five frequencies of the double-image gravitational lens JVAS B0218+357, made to establish the precise registration of the A and B lensed image positions. The…

Astrophysics · Physics 2009-11-11 Rupal Mittal , Richard Porcas , Olaf Wucknitz , Andy Biggs , Ian Browne

Using the Very Long Baseline Array and the European VLBI Network, we have observed 22.2 GHz H_2O and 1612 MHz OH masers in the "water fountain" source IRAS 18460-0151. The H_2O maser spectrum has a very wide line-of-sight velocity range…

Solar and Stellar Astrophysics · Physics 2015-06-16 Hiroshi Imai , Shuji Deguchi , Jun-ichi Nakashima , Sun Kwok , Philip J. Diamond

The VLA was used to determine precise positions for 4765-MHz OH maser emission sources toward star-forming regions which had been observed about seven months earlier with the Effelsberg 100-meter telescope. The observations were successful…

Astrophysics · Physics 2009-11-10 Patrick Palmer , W. M. Goss , J. B. Whiteoak

We observed at 22 GHz with the VLBI array VERA a sample of 1536 sources with correlated flux densities brighter than 200 mJy at 8 GHz. One half of target sources has been detected. The detection limit was around 200 mJy. We derived the…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-26 Leonid Petrov , Mareki Honma , Katsunori M. Shibata

The KVN(Korean VLBI Network)-style simultaneous multi-frequency receiving mode is demonstrated to be promising for mm-VLBI observations. Recently, other Very long baseline interferometry (VLBI) facilities all over the globe start to…

We present ATCA observations of the H2O maser line and radio continuum at 18.0GHz and 22.8GHz, toward a sample of 192 massive star forming regions containing several clumps already imaged at 1.2mm. The main aim of this study is to…

Astrophysics of Galaxies · Physics 2015-06-12 A. Sanchez-Monge , M. T. Beltran , R. Cesaroni , F. Fontani , J. Brand , S. Molinari , L. Testi , M. Burton

We present Very Large Array (VLA) observations of the water maser emission towards IRAS 16552-3050. The maser emission shows a velocity spread of ~170 km/s, and a bipolar distribution with a separation between the red and blueshifted groups…

Astrophysics · Physics 2009-11-13 Olga Suárez , J. F. Gómez , L. F. Miranda

We present the results of a 22GHz H2O maser survey toward a new sample of AGB and post-AGB star candidates. Most of the objects are selected for the first time based on the AKARI data, which have high flux sensitivity in the mid-infrared…

Solar and Stellar Astrophysics · Physics 2015-06-15 Bosco Yung , Jun-ichi Nakashima , Hiroshi Imai , Shuji Deguchi , Christian Henkel , Sun Kwok

In this document we layout a new method to achieve "bona fide" high precision Very-Long-Baseline-Interferometry (VLBI) astrometric measurements of frequency-dependent positions of celestial sources (even) in the high (mm-wavelength)…

Instrumentation and Methods for Astrophysics · Physics 2009-10-08 Richard Dodson , Maria J. Rioja

This paper describes the overview of the FLASHING (Finest Legacy Acquisitions of SiO-/ H$_2$O-maser Ignitions by the Nobeyama Generation) project promoted using the 45 m telescope of Nobeyama Radio Observatory, which aims to intensively…

W75N(B) is a massive star-forming region that contains three radio continuum sources (VLA 1, VLA 2, and VLA 3), which are thought to be three massive young stellar objects at three different evolutionary stages. VLA 1 is the most evolved…

Solar and Stellar Astrophysics · Physics 2014-05-28 G. Surcis , W. H. T. Vlemmings , H. J. van Langevelde , C. Goddi , J. M. Torrelles , J. Cantó , S. Curiel , S. -W. Kim , J. -S. Kim

We report on the results of two epochs of Very Long Baseline Array (VLBA) observations of the 22 GHz water masers toward IRAS 19190+1102. The water maser emission from this object shows two main arc-shaped formations perpendicular to their…

Solar and Stellar Astrophysics · Physics 2015-05-18 F. M. Day , Y. M. Pihlstrom , M. J. Claussen , R. Sahai

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…

Instrumentation and Methods for Astrophysics · Physics 2015-05-18 I. Marti-Vidal , E. Ros , M. A. Perez Torres , J. C. Guirado , S. Jimenez-Monferrer , J. M. Marcaide

We present new Far Ultraviolet Spectroscopic Explorer (FUSE) observations of Mira A's wind-accreting companion star, Mira B. We find that the strongest lines in the FUSE spectrum are H2 lines fluoresced by H I Lyman-alpha. A previously…

Astrophysics · Physics 2009-11-10 Brian E. Wood , Margarita Karovska

We propose bigradient phase referencing (BPR), a new radio-observation technique, and report its performance using the Japanese very-long-baseline-interferometry network (JVN). In this method, a weak source is detected by phase-referencing…

The class II methanol maser source G9.62+0.20E undergoes periodic flares at both 6.7 and 12.2 GHz. The flare starting in 2001 October was observed at seven epochs over three months using the VLBA at 12.2 GHz. High angular resolution images…

Astrophysics · Physics 2009-11-10 S. Goedhart , V. Minier , M. J. Gaylard , D. J. van der Walt

Space Very-Long-Baseline-Interferometry (S-VLBI) observations at high frequencies hold the prospect of achieving the highest angular resolutions and astrometric accuracies, resulting from the long baselines between ground and satellite…

Instrumentation and Methods for Astrophysics · Physics 2012-01-12 M. Rioja , R. Dodson , J. Malarecki , Y. Asaki

We have conducted phase-reference multi-epoch observations of the 22.2 GHz water masers using the VLBA and multi-frequency study of the continuum emission using the VLA towards the high-mass SFR AFGL 5142. The water maser emission comes…

Astrophysics · Physics 2009-11-11 C. Goddi , L. Moscadelli

Spatial phase-referencing in dual-field optical interferometry is reconsidered. Our analysis is based on the 2-sample variance of the differential phase between target and reference star. We show that averaging over time of the atmospheric…

Astrophysics · Physics 2009-11-07 Gerard Daigne , Jean-Francois Lestrade