Detection of optical outburst activity in the BL Lac object OT 081 (PKS 1749+096)

ATel #9259; Thomas J. Balonek, R. William Stahlin, Katie J. Chapman, Alina Sabyr, Zachary R. Weaver, Saiyang Zhang (Colgate Univ), Samantha J. Boni (Bridgewater State Univ & Colgate Univ), Valeri M. Larionov, Daria Morozova (St. Petersburg Univ, Russia) and Svetlana Jorstad (Boston Univ & St. Petersburg Univ)
on 23 Jul 2016; 23:23 UT
Credential Certification: Thomas J. Balonek (tbalonek@colgate.edu)

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We report a strong optical outburst in the BL Lac object OT 081 (also known as PKS 1749+096, 4C +09.57) that peaked during the interval 2016 July 16 to 20 at R ~ 14.9. This optical activity is likely associated with a gamma ray flare on July 9 reported by Gonzalez and Thompson (ATel #9231). The Fermi LAT team has informed us of continuing gamma-ray and X-ray activity of the source, peaking near simultaneously with the optical outburst.

Our optical (R) observations reveal that, after four months of only minor variations between R ~ 17.6 and 16.8, OT 081 underwent a steady brightening of over 2.75 magnitudes in a forty-day interval between 2016 June 7 and July 16, reaching an observed peak brightness of R ~ 14.9. This optical outburst is the brightest OT 081 has been observed by our groups since the significantly brighter outbursts in 2007 and 2008 (both which peaked at R ~ 13.9), and is slightly brighter than observed in 2010 (peak R ~ 15.1).

The optical observations were obtained in St.Petersburg (LX-200), Crimea (AZT-8+ST-7) and Lowell (Perkins), and Colgate University Foggy Bottom Observatory (Ferson 0.4-m; FBO). The FBO measurements are averages of a dozen two-minute images taken in a sequence lasting forty-five minutes. There may be a small systematic offset between measurements from the FBO and the other observatories.

2016-06-07 21.86 UT (JD 2457547.411) R=17.64 +/-0.03 AZT-8+ST7

2016-06-12 08.33 UT (JD 2457551.847) R=17.38 +/-0.03 Perkins

2016-06-15 08.52 UT (JD 2457554.855) R=16.94 +/-0.01 Perkins

2016-06-16 08.16 UT (JD 2457555.840) R=16.94 +/-0.02 Perkins

2016-06-27 21.19 UT (JD 2457567.383) R=16.41 +/-0.01 AZT-8+ST7

2016-07-01 03.91 UT (JD 2457570.663) R=16.08 +/-0.03 FBO

2016-07-03 04.66 UT (JD 2457572.694) R=16.12 +/-0.02 FBO

2016-07-07 21.48 UT (JD 2457577.395) R=15.50 +/-0.01 AZT-8+ST7

2016-07-08 20.64 UT (JD 2457578.360) R=15.57 +/-0.01 AZT-8+ST7

2016-07-09 20.21 UT (JD 2457579.342) R=15.51 +/-0.03 AZT-8+ST7

2016-07-11 03.53 UT (JD 2457580.647) R=15.49 +/-0.02 FBO

2016-07-11 21.01 UT (JD 2457581.376) R=15.85 +/-0.01 AZT-8+ST7

2016-07-12 02.32 UT (JD 2457581.597) R=15.73 +/-0.02 FBO

2016-07-12 20.71 UT (JD 2457582.363) R=15.68 +/-0.01 AZT-8+ST7

2016-07-13 04.12 UT (JD 2457582.672) R=15.57 +/-0.02 FBO

2016-07-14 02.37 UT (JD 2457583.599) R=15.34 +/-0.02 FBO

2016-07-15 05.67 UT (JD 2457584.736) R=15.26 +/-0.02 FBO

2016-07-16 03.44 UT (JD 2457585.643) R=14.87 +/-0.02 FBO

2016-07-19 03.83 UT (JD 2457588.659) R=14.95 +/-0.02 FBO

2016-07-20 03.51 UT (JD 2457589.646) R=14.96 +/-0.02 FBO

2016-07-20 22.36 UT (JD 2457590.444) R=15.03 +/-0.01 AZT-8+ST7

2016-07-21 03.51 UT (JD 2457590.646) R=15.02 +/-0.02 FBO

2016-07-21 18.65 UT (JD 2457591.277) R=15.17 +/-0.01 AZT-8+ST7

2016-07-22 03.72 UT (JD 2457591.655) R=15.21 +/-0.02 FBO

2016-07-22 19.80 UT (JD 2457592.325) R=15.14 +/-0.01 AZT-8+ST7

Student research participation at Colgate University is supported by the NASA / New York Space Grant, an NSF grant to the Keck Northeast Astronomy Consortium, and Colgate Schlichting fellowships.

Further multi-wavelength observations are encouraged, as the strong optical outbursts in 2007 and 2008 exhibited multiple peaks.