Volume 481, Number 2, April II 2008
|Page(s)||L79 - L82|
|Published online||25 February 2008|
Letter to the Editor
Multifrequency monitoring of the blazar 0716+714 during the GASP-WEBT-AGILE campaign of 2007*
INAF, Osservatorio Astronomico di Torino, Italy e-mail: firstname.lastname@example.org
2 Astronomical Institute, St.-Petersburg State University, Russia
3 Pulkovo Observatory, Russia
4 Abastumani Astrophysical Observatory, Georgia
5 Astrophysikalisches Institut Potsdam, Germany
6 Landessternwarte Heidelberg-Königstuhl, Germany
7 Tuorla Observatory, University of Turku, Finland
8 Department of Astronomy, University of Michigan, MI, USA
9 Metsähovi Radio Obs., Helsinki Univ. of Tech. TKK, Finland
10 Radio Astronomy Lab. of Crimean Astrophysical Obs., Ukraine
11 Max-Planck-Institut für Radioastronomie, Germany
12 Circolo Astrofili Talmassons, Italy
13 SARA Observatory, Florida International University, FL, USA
14 INAF, Osservatorio Astrofisico di Catania, Italy
15 Astrophys. Inst., Dept. of Phys. & Astron., Ohio Univ., OH, USA
16 Oss. Astronomico della Regione Autonoma Valle d'Aosta, Italy
17 Armenzano Astronomical Observatory, Italy
18 Instituto de Astrofísica de Andalucía, CSIC, Spain
19 INAF, Osservatorio Astronomico di Roma, Italy
20 INAF, Osservatorio Astronomico di Teramo, Italy
21 Agrupació Astronòmica de Sabadell, Spain
22 Instituto de Astronomía, UNAM, Mexico
23 INAF, Istituto di Radioastronomia Sezione di Noto, Italy
24 INAF, IASF-Roma, Italy
25 INAF, IASF-Milano, Italy
Accepted: 15 February 2008
Aims. Since the CGRO operation in 1991–2000, one of the primary unresolved questions about the blazar γ-ray emission has been its possible correlation with the low-energy (in particular optical) emission. To help answer this problem, the Whole Earth Blazar Telescope (WEBT) consortium has organized the GLAST-AGILE Support Program (GASP) to provide the optical-to-radio monitoring data to be compared with the γ-ray detections by the AGILE and GLAST satellites. This new WEBT project started in early September 2007, just before a strong γ-ray detection of 0716+714 by AGILE.
Methods. We present the GASP-WEBT optical and radio light curves of this blazar obtained in July–November 2007, about various AGILE pointings at the source. We construct NIR-to-UV spectral energy distributions (SEDs), by assembling GASP-WEBT data together with UV data from the Swift ToO observations of late October.
Results. We observe a contemporaneous optical-radio outburst, which is a rare and interesting phenomenon in blazars. The shape of the SEDs during the outburst appears peculiarly wavy because of an optical excess and a UV drop-and-rise. The optical light curve is well sampled during the AGILE pointings, showing prominent and sharp flares. A future cross-correlation analysis of the optical and AGILE data will shed light on the expected relationship between these flares and the γ-ray events.
Key words: galaxies: active / galaxies: BL Lacertae objects: general / galaxies: BL Lacertae objects: individual: S5 0716+71 / galaxies: jets
© ESO, 2008
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