Issue |
A&A
Volume 489, Number 3, October III 2008
|
|
---|---|---|
Page(s) | L33 - L36 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:200810423 | |
Published online | 11 September 2008 |
Letter to the Editor
Serendipitous VLBI detection of rapid, large-amplitude, intraday variability in QSO 1156+295
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: [tsavolainen;ykovalev]@mpifr-bonn.mpg.de
2
Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow, Russia
Received:
19
June
2008
Accepted:
18
August
2008
Aims. We report a serendipitous detection of rapid, large amplitude flux density variations in the highly core-dominated, flat-spectrum radio quasar 1156+295 during an observing session at the Very Long Baseline Array (VLBA).
Methods. The source was observed as a part of the MOJAVE survey programme with the VLBA at 15 GHz on February 5, 2007. Large amplitude variability in the correlated flux density, unexplainable in terms of the source structure, was first discovered while processing the data, and later confirmed by calibrating the antenna gains using 24 other sources observed in the experiment.
Results. The source shows variations in the correlated flux density as high as 40% on a timescale of only 2.7 h. This places 1156+295 between the classical IDV sources and the so-called intra-hour variables. The observed variability timescale and the modulation index of 13% are consistent with interstellar scintillation by a nearby, highly turbulent scattering screen. The large modulation index at 15 GHz implies a scattering measure that is atypically high for a high galactic latitude source such as 1156+295.
Key words: galaxies: active / galaxies: jets / galaxies: quasars: individual: QSO 1156+295 / techniques: interferometric / scattering / ISM: structure
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.