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Swift follow-up of the high-redshift blazar PKS 1329-049

ATEL # 2739; F. D'Ammando (INAF-IASF Palermo), K. V. Sokolovsky (MPIfR/ASC Lebedev), D. Donato (NASA/GSFC) on behalf of the Fermi Large Area Telescope Collaboration and J. Gelbord (PSU)
on 15 Jul 2010; 16:59 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Filippo D'Ammando (

Subjects: Optical, Ultra-Violet, X-ray, Gamma Ray, >GeV, Request for Observations, AGN, Quasars

Following the Fermi-LAT detection of a GeV flare from the high-redshift blazar PKS 1329-049 (also known as 1FGL J1331.9-0506, Abdo et al. 2010, ApJS, 188, 405; z = 2.15, Thompson et al. 1990, PASP, 102, 1235) on July 07, 2010 (ATel #2728) Swift Target of Opportunity observations were performed on July 10 and 13, 2010, with an exposure of about 5.0 ksec and 4.2 ksec, respectively.

The Swift/XRT spectrum of PKS 1329-049 can be fit (0.3-10 keV) with an absorbed power law model with a neutral hydrogen column density consistent with the Galactic value in the direction of the source (n_H = 2.18x10^20 cm^-2, Kalberla et al. 2005) and a photon index of 1.37+/-0.14 and 1.38+/-0.15, respectively. The corresponding unabsorbed 0.3-10 keV fluxes are (4.5+/-0.6) and (4.9+/-0.6)x10^-12 erg cm^-2 s^-1. The fluxes observed are a factor of two higher than that previously observed by Swift/XRT on August 11, 2009 (2.3+/-0.4x10^-12 erg cm^-2 s^-1, with a photon index of 1.39+/-0.19) confirming the high activity of the source also in X-rays. Notwithstanding the difference in fluxes we noted that the photon indexes are well compatible between the observations performed on 2009 and 2010. Moreover, the same flux level observed on 10 and 13 July suggests an ongoing activity of the source.

Simultaneous Swift/UVOT observations found PKS 1329-049 about 0.5 mag brighter in U band on July 10, 2010 (U = 17.28+/-0.09) compared to the UVOT observation performed on August 11, 2009 (U = 17.75+/-0.05). A slight decrease was observed by UVOT in U band on July 13, 2010 (U = 17.48+/-0.08).

In consideration of the ongoing activity of this source, confirmed also by the Swift X-ray observations, we strongly encourage further multiwavelength observations. For this source the LAT contact person is D. Donato (

We thank the Swift Team for their rapid scheduling of these observations.

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R. E. Rutledge , Editor
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