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Swift follow-up of the renewed flaring phase of blazar SBS 1150+497

ATel #13285; Rukaiya Khatoon (Tezpur Univ.), V. Jithesh (IUCAA), Raj Prince (RRI), Zahir Shah (IUCAA), Ranjeev Misra (IUCAA) and Rupjyoti Gogoi (Tezpur Univ.)
on 11 Nov 2019; 18:45 UT
Credential Certification: V. Jithesh (jitheshthejus@gmail.com)

Subjects: Optical, Ultra-Violet, X-ray, Gamma Ray, AGN, Blazar

The renewed gamma-ray flare from a blazar, SBS 1150+497 (4C 49.22; R.A = 11h53m24.47s, Dec. = +49d31m08.83s, (J2000), Johnston et al. 1995, AJ, 110, 880) located at z=0.334 (Lynds & Wills 1968, ApJ, 153, L23), was observed on 2019 October 30 using Fermi-LAT after eight years of its quiescence state (ATel #13254). We conducted a follow-up observation of this flaring activity using Swift (XRT and UVOT) observatory on 2019 November 8 (observation ID: 00037519003) for an exposure of ~ 2.1 ks.

We report the preliminary analysis results using the Swift-XRT and UVOT data. We extracted the Swift-XRT spectrum (0.3-10 keV band), which can be fitted with an absorbed power-law model, where the absorption is fixed at the Galactic value of N_H = 2.13 x 10^20 cm^-2 (Kalberla et al. 2005, A&A, 440, 775). The resulting unabsorbed flux is 5.80 (+0.85, -0.80) x 10^-12 erg cm^-2 s^-1 with a photon index of 1.72+/-0.18. Previous observations conducted during the flaring period (on 2011 May 2 and 2011 May 15) showed an increase in the flux from (7.6+/-0.6) x 10^-12 erg cm^-2 s^-1 to (2.1+/-0.1) x 10^-11 erg cm^-2 s^-1, by a factor of ~ 3 and the photon index changed from 1.77 to 2.04 (ATel #3353). The photon index obtained from our analysis is comparable to the previous observation conducted on 2011 May 2, however, the flux is marginally lower. Referring to the X-ray activity in 2011, we expect the flux value obtained on 2019 November 8 may be increased after a few weeks.

The UVOT observation was performed with four filters, viz. U, B, UVW1 and UVW2 with time exposure as 314.53s, 314.50s, 629.46s and 856.76s, respectively. The magnitudes obtained in the AB system are 17.27 +/- 0.04 mag (statistical error only) for U band, 17.23 +/- 0.05 mag for B band, 17.29 +/- 0.03 mag for UVW1 band and 17.24 +/- 0.03 mag for UVW2 band.

We encourage further multi-wavelength observations of this object. We would like to thank the Swift Team for the extremely rapid and efficient scheduling of the ToO observation.