Prior to its strong outbursts in 2011, blazar 4C +71.07 was a weak source for Fermi’s LAT. These images centered on 4C +71.07 show the rate at which the LAT detected gamma rays with energies above 100 million electron volts; lighter colors equal higher rates. The image at left covers 2.5 years, from the start of Fermi’s mission to 2011. The image at right shows 10 weeks of activity in late 2011, when 4C +71.07 produced its strongest outburst. A more frequently active blazar, S5 0716+71, appears in both images.
Credit: NASA/DOE/Fermi LAT Collaboration