We report the observation by the Compton Gamma Ray Observatory of a spectacular flare of radio source PKS 1622−297. A peak flux of (17 ± 3) × 10 −6 cm −2 s −1 (E > 100 MeV) was observed. The corresponding isotropic luminosity is 2.9×10 49 erg/s. We find that PKS 1622−297 exhibits γ-ray intra-day variability. A flux increase by a factor of at least 3.6 was observed to occur in less than 7.1 hours (with 99% confidence). Assuming an exponential rise, the corresponding doubling time is less than 3.8 hours. A significant flux decrease by a factor of ∼2 in 9.7 hours was also observed. Without beaming, the rapid flux change and large isotropic luminosity are inconsistent with the Elliot-Shapiro condition (assuming that gas accretion is the immediate source of power for the γ-rays). This inconsistency suggests that the γ-ray emission is beamed. A minimum Doppler factor of 8.1 is implied by the observed lack of pair-production opacity (assuming x-rays are emitted co-spatially with the γ-rays). Simultaneous observation by EGRET and OSSE finds a spectrum adequately fit by a power law with photon index of −1.9. Although the significance is not sufficient to establish this beyond doubt, the high-energy γ-ray spectrum appears to evolve from hard to soft as a flare progresses. quasars:general -quasars:individual:PKS 1622−297 -gamma rays: observations
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.