IC 3599: Back in an High Optical/UV Flux State

ATel #7812; Dirk Grupe (Morehead State University), S. Komossa (Max-Planck-Institut fuer Radioastronomie), & Richard Saxton (European Space Astronomy Center)
on 20 Jul 2015; 02:01 UT
Credential Certification: Dirk Grupe (dgrupe007@gmail.com)

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We report on an unusually high optical/UV flux state of the Seyfert 1.9 galaxy IC 3599 discovered by Swift on 2015 July 06. Compared with the previous observation on March 29 (Grupe et al., 2015, ApJ 803, L28) it doubled its flux in the optical and UV filters. New observations on July 12, 15, and 19 confirmed this high state. However, in X-rays, IC 3599 remained at the level seen before in March at about (1.3+0.4-0.3)e-16 W/m2. The observed magnitudes measured in all 6 UVOT filters are currently (July 19): V: 15.94+/-0.06 B: 16.57+/-0.06 U: 16.39+/-0.07 W1: 16.70+/-0.08 M2: 16.74+/-0.09 W2: 16.78+/-0.07 IC 3599 has had a history of high-amplitude X-ray outbursts seen during the ROSAT All-Sky Survey and most recently in February 2010 (Grupe et al., 1995, A&A 299; Brandt et al., 1995, MNRAS 273; Grupe et al., 2015, ApJ 803). During the outburst in 1990 dramatic changes in the optical spectrum of IC 3599 were observed (see Grupe et al. 1995 and Brandt et al. 1995). Most likely these events are due to accretion disk instabilities. The current event may be the precursor of one of these events. We will continue monitoring with Swift with a weekly cadence until IC 3599 will go into its sun-constraint on August 10. We encourage optical observers to obtain an optical spectrum of IC 3599. We thank Neil Gehrels for approving our most recent Swift ToO requests and the Swift science operation team for executing these so promptly.