Swift observations in all filters of the Seyfert galaxy NGC 1566 in outburst

ATel #11903; Dirk Grupe (Morehead State University), S. Komossa (MPIfR), Norbert Schartel (ESAC)
on 2 Aug 2018; 02:48 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)

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We report on follow-up Swift observations of the nearby Seyfert 1.5 galaxy NGC 1566 (Dai et al., ATel #11893) which was discovered in an outburst in hard X-rays by Integral on 2018-June-12-19 (Ducci et al., ATel #11754). Swift observations immediately after this discovery showed that the X-ray flux in the XRT had significantly increased (Ferrigno et al., ATel #11783) as well as in the UV (Kuin et al., ATel #11786). The most recent Swift observations from July 10, 17, 24, and 31 confirm the high X-ray and UV flux states, but may indicate that the peak of the outburst was reached around July 10. The current flux in the 0.3-10 keV band is (6.79+/-0.19)e-14 W/m2 which corresponds to a 0.3-10 keV luminosity of 3e35 W assuming a distance of 20 Mpc. The enhanced X-ray position (Goad et al. 2007; Evans et al. 2009) at RA-2000 = 04 20 00.37, Dec-2000=-54 56 16.6 (uncertainty 1.4") corresponds to the optical position of the center of the galaxy. Our Swift UVOT observation on 2018-July-31 was performed in the filters V, B, U, W1, and W2. Compared with the 2007 observation we found the following magnitudes: V: 13.49, 13.01 (2007, 2018); B: 14.40, 13.40; U: 14.18, 12.59; W1: 14.50, 12.48; W2: 15.09, 12.60 (note that the extraction radius was 5 arcsec, and that the host galaxy significantly contributes to the magnitudes at low-state). The W2 magnitude is slightly lower than that reported by Kuin et al. (ATel #11786). The uncertainties of all these observations are typically of the order of 0.04 mag and the values given here are not corrected for Galactic reddening. The reddening however in the direction of NGC 1566 is low with E(B-V) = 0.008 mag. We would like to thank Brad Cenko for approving our ToO request and the Swift team for performing the observations. We continue monitoring this AGN with Swift.