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In the late 1990s, the Optical Gravitational Lensing Experiment (OGLE) team conducted the second phase of their long-term monitoring programme, OGLE-II, which since has been superseded by OGLE-III. All the monitoring data of this second…

Astrophysics · Physics 2009-11-13 I. Snellen , R. van der Burg , M. de Hoon , F. Vuijsje

Active Galactic Nuclei (AGN) are ideal sources for multi-wavelength studies as their emission can cover almost 20 orders of magnitude in frequency from the radio to the gamma-ray band. After reviewing their basic properties, I will assess…

Astrophysics · Physics 2007-05-23 Paolo Padovani

Previous studies based on the latest realisation of the International Celestial Reference Frame (ICRF3) have suggested a correlation between astrometric properties (such as the radio-optical offset) and redshift for active galactic nuclei…

Instrumentation and Methods for Astrophysics · Physics 2026-04-01 Zhiyun Zhang , N. Liu , Xiaxuan Zhang , I. Nurul Huda , Sufen Guo , Z. Zhu , J. -C. Liu , J. Yao , Z. -W. Wang , H. -F. Yu , D. -D. Zhang

The Off-plane Grating Rocket Experiment (OGRE) is a soft X-ray grating spectrometer to be flown on a suborbital rocket. The payload is designed to obtain the highest-resolution soft X-ray spectrum of Capella to date with a resolution goal…

We have carried out a deep X-ray observation on a typical Galactic plane region with the Chandra ACIS-I instrument with unprecedented sensitivity and spatial resolution, and detected 274 unidentified X-ray point sources in the \~500 arcmin2…

The Galactic center offers us a unique opportunity to test General Relativity (GR) with the orbits of stars around a supermassive black hole. Observations of these stars have been one of the great successes of adaptive optics on 8-10 m…

Astrophysics of Galaxies · Physics 2017-11-20 Tuan Do , Aurelien Hees , Arezu Dehghanfar , Andrea Ghez , Shelley Wright

This paper joins a series compiling consistent emission line measurements of large AGN spectral databases, useful for reliable statistical studies of emission line properties. It is preceded by emission line measurements of 993 spectra from…

For the first time, we present a systematic search for galaxies with extended emission line and potential outflow features using \textit{JWST} medium-band images in the GOODS-S field. This is done by comparing the morphology in medium-band…

We tackle the problem of accurate optical tracking of distant man-made probes, on Halo orbit around the Earth-Sun libration point L2 and beyond, along interplanetary transfers. The improved performance of on-target tracking, especially when…

Instrumentation and Methods for Astrophysics · Physics 2016-04-06 Alberto Buzzoni , Giuseppe Altavilla , Silvia Galleti

We interpret the recent discovery of a preferable VLBI/Gaia offset direction for radio-loud active galactic nuclei (AGNs) along the parsec-scale radio jets as a manifestation of their optical structure on scales of 1 to 100 milliarcseconds.…

High Energy Astrophysical Phenomena · Physics 2017-08-25 Leonid Petrov , Yuri Y. Kovalev

(Abridged) Conventional radio surveys of deep fields ordinarily have arc-second scale resolutions often insufficient to reliably separate radio emission in distant galaxies originating from star-formation and AGN-related activity. Very long…

GRAVITY is an adaptive optics assisted Beam Combiner for the second generation VLTI instrumentation. The instrument will provide high-precision narrow-angle astrometry and phase-referenced interferometric imaging in the astronomical K-band…

A key feature of active galactic nuclei (AGN) is their variability across all wavelengths. Typically, AGN vary by a few tenths of a magnitude or more over periods lasting from hours to years. By contrast, extreme variability of AGN -- large…

High Energy Astrophysical Phenomena · Physics 2024-03-12 Summer A. J. McLaughlin , James R. Mullaney , Stuart P. Littlefair

For sensitive optical interferometry, it is crucial to control the evolution of the optical path difference (OPD) of the wavefront between the individual telescopes of the array. The OPD between a pair of telescopes is induced by…

Instrumentation and Methods for Astrophysics · Physics 2021-12-28 Saavidra Perera , Jörg-Uwe Pott , Julien Woillez , Martin Kulas , Wolfgang Brandner , Sylvestre Lacour , Felix Widmann

We present an analysis of the potential follow-up polarimetry microlensing observation to study the stellar atmospheres of the distant stars. First, we produce synthetic microlensing events using the Galactic model, stellar population, and…

Solar and Stellar Astrophysics · Physics 2021-01-20 Elahe Khalouei , Sedighe Sajadian , Sohrab Rahvar

We present measurements of broad emission lines and virial estimates of supermassive black hole masses ($M_{BH}$) for a large sample of ultra-hard X-ray selected active galactic nuclei (AGNs) as part of the second data release of the BAT…

The VLTI Spectro Imager project aims to perform imaging with a temporal resolution of 1 night and with a maximum angular resolution of 1 milliarcsecond, making best use of the Very Large Telescope Interferometer capabilities. To fulfill the…

We present a new gravitational lens modelling technique designed to model high-resolution interferometric observations with large numbers of visibilities without the need to pre-average the data in time or frequency. We demonstrate the…

Instrumentation and Methods for Astrophysics · Physics 2021-01-06 Devon Powell , Simona Vegetti , John P. McKean , Cristiana Spingola , Francesca Rizzo , Hannah R. Stacey

Polarized synchrotron emission at meter to centimeter wavelengths provides an effective tracer of the Galactic magnetic field. Calculating Faraday depth, the most useful parameter for mapping the line-of-sight magnetic field, requires…

We present a method to map the artificial sky brightness across large territories in astronomical photometric bands with a resolution of approximately 1 km. This is useful to quantify the situation of night sky pollution, to recognize…

Astrophysics · Physics 2009-10-31 P. Cinzano , F. Falchi , C. D. Elvidge , K. E. Baugh
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