Swift follow-up of the high redshift flaring blazar 4C +71.07 (S5 0836+71)
ATel #3835; F. D'Ammando (INAF-IRA Bologna) on behalf of the Fermi Large Area Telescope Collaboration, and A. Falcone, M. Stroh, E. Hoversten (Penn State Univ.)
on 30 Dec 2011; 07:10 UT
Credential Certification: Filippo D'Ammando (filippo.dammando@iasf-roma.inaf.it)
Subjects: Optical, Ultra-Violet, X-ray, AGN, Blazar, Quasar
Following the gamma-ray flare of the high redshift flat spectrum radio quasar 4C +71.07 (also known as S5 0836+71; 1FGL J0842.2+7054, Abdo et al. 2010, ApJS, 188, 405; 2FGL J0841.6+7052, Abdo et al. 2011, submitted to ApJS, ArXiv:1108.1435) detected by Fermi LAT on 2011 December 25 (ATel #3831), a Swift target of opportunity observation was performed on December 27.
Swift/XRT data were taken in Photon Counting mode for a total exposure of about 2.5 ksec. The X-ray spectrum (0.3-10 keV) can be fit by an absorbed power law model with a HI column density consistent with the Galactic value in the direction of the source (n_H = 2.83 x 10^20 cm^-2, Kalberla et al. 2005, A&A, 440, 775) and a photon index of 1.32+/-0.08. The corresponding observed 0.3-10 keV flux is (4.09+/-0.28) x10^-11 erg cm^-2 s^-1. This flux is about 75% higher than that observed by Swift/XRT on 2011 November 6, (2.32+/-0.20) x10^-11 erg cm^-2 s^-1, with a photon index of 1.35+/-0.10.
Taking into consideration the Swift/XRT observations performed during 2006-2011, 4C +71.07 on 2011 December 27 reached the highest count rate in the 0.3-10 keV energy range (see http://www.swift.psu.edu/monitoring/source.php?source=0836+710 ).
Simultaneous Swift/UVOT observations on 2011 December 27 found 4C +71.07 at about the same level observed on 2011 October 7, with only a slight increase in the optical part of the spectrum. The measured Vega magnitudes are:
| Band | 2011-10-07 | 2011-12-27 |
|---|
| V | 17.01+/-0.15 | 16.91+/-0.12 |
| B | 17.20+/-0.11 | 17.01+/-0.07 |
| U | 16.35+/-0.06 | 16.18+/-0.06 |
| W1 | 17.19+/-0.09 | 17.20+/-0.10 |
| M2 | 17.55+/-0.12 | 17.53+/-0.13 |
| W2 | 17.95+/-0.07 | 17.90+/-0.10 |
Further multiwavelength observations are encouraged. For this source the Fermi LAT contact persons are K. Sokolovsky (kirx@scan.sai.msu.ru) and D.J. Thompson (David.J.Thompson@nasa.gov).
We thank the Swift team for their rapid scheduling of this observation.
