Optical variability of some quasars important to ICRF-Gaia CRF link
نویسندگان
چکیده
منابع مشابه
Gaia Space Mission and Quasars
Quasars are often considered to be point-like objects. This is largely true and allows for an excellent alignment of the optical positional reference frame of the ongoing ESA mission Gaia with the International Celestial Reference Frame. But presence of optical jets in quasars can cause shifts of the optical photo-centers at levels detectable by Gaia. Similarly, motion of emitting blobs in the ...
متن کاملOptical Monitoring of Quasars: I. Variability
We present an analysis of quasar variability from data collected during a photometric monitoring of 50 objects carried out at CNPq/Laboratório Nacional de Astrof́ısica, Brazil, between March 1993 and July 1996. A distinctive feature of this survey is its photometric accuracy, ∼ 0.02 V mag, achieved through differential photometry with CCD detectors, what allows the detection of faint levels of v...
متن کاملGaia Data Release 1 - Reference frame and optical properties of ICRF sources
Context. As part of the data processing for Gaia Data Release 1 (Gaia DR1) a special astrometric solution was computed, the so-called auxiliary quasar solution. This gives positions for selected extragalactic objects, including radio sources in the second realisation of the International Celestial Reference Frame (ICRF2) that have optical counterparts bright enough to be observed with Gaia. A s...
متن کاملCan Microlensing Explain the Long-Term Optical Variability of Quasars?
Although controversial, the scenario of microlensing as the dominant mechanism for the long-term optical variability of quasars does provide a natural explanation for both the statistical symmetry, achromaticity and lack of cosmological time dilation in quasar light curves. Here, we investigate to what extent dark matter populations of compact objects allowed in the currently favored ΩM = 0.3, ...
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ژورنال
عنوان ژورنال: Serbian Astronomical Journal
سال: 2019
ISSN: 1450-698X,1820-9289
DOI: 10.2298/saj1999055j