Alert Notice 611: Flaring of Blazar 3C 279

January 26, 2018: AAVSO member/observer Adolfo Darriba (Madrid, Spain) informs us that Dr. Dave Thompson, Multiwavelength Coordinator for the Large Area Telescope (LAT) of NASA's Fermi Gamma-Ray Telescope, on behalf of the Fermi LAT Collaboration has called for observations of the blazar 3C 279, which is undergoing a major gamma-ray flare.

The Fermi LAT team reported that the gamma-ray flux level reached a high state on 2018 January 15 UT, a few days after it began rising (ATel #11189; P. van Zyl (Hartebeesthoek Radio Astronomy Observatory) and R. Ojha (NASA/GSFC/UMBC) on behalf of the Fermi LAT Collaboration). As of January 17 it was higher than had been recorded since the flare that occurred in 2015.

Lucarelli et al. subsequently reported that the Italian Space Agency's X-ray/gamma-ray astronomical satellite AGILE detected the flare on 2018 January 18-19 UT (ATel #11200; F. Lucarelli (SSDC and INAF/OAR) et al.) and the gamma-ray flux level was higher than at the time of the report by van Zyl and Ojha.

3C 279 is also presently in an optical high state, as indicated by recent observations submitted to the AAVSO International Database. Observations by K. Hills (Hartford, Cheshire, UK) and A. Darriba  show 3C 279 brightening since mid-December 2017:

2017 Dec. 15.22535 UT, 16.188 V +/-0.276 (Hills);
2017 Dec. 21.24036, 15.324 V +/-0.173 (Hills);
2018 Jan. 13.29603, 15.006 V +/-0.108 (Hills);
2018 Jan. 20.09834, 14.388 V +/-0.017 (Darriba);
2018 Jan. 20.10943, 14.405 V +/-0.129 (Hills);
2018 Jan. 23.19677, 14.503 V +/-0.149 (Hills);

This blazar has been in the AAVSO observing program since 1992, and has an optical range in V of 13.0 - 18.0. Multiple observation reports confirm this optical high state (ATels #11190 (D'Ammando et al.), #11196 (Marchini et al.), #11202 (A. Kaur et al.), #11216 (Turner and Miller)).

Observations are requested in V until 3C 279 has returned to its low state (V~16-18). Other bands are welcome, as are visual observations.

Coordinates (2000.0) (optical): R.A. 12 56 11.17  Dec. -05 47 21.5

Charts: Finder charts with a comparison star sequence for 3C 279, which is in Virgo, may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations to the AAVSO International Database using the name 3C 279.

A thread has been created for this event on the AAVSO's Campaigns and Observation Reports Forum at

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.


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