Published in:

Astrophysical Journal 621,1 (2005) 181-187;


The blazar 1ES 1959+650 was observed in a flaring state with the Whipple 10 m Imaging Atmospheric Cerenkov Telescope in 2002 May. A spectral analysis has been carried out on the data from that time period, and the resulting very high energy gamma-ray spectrum (E greater than or equal to 316 GeV) can be well fitted by a power law of differential spectral index alpha = 2.78 +/- 0.12(stat) +/- 0.21(sys). On 2002 June 4, the source flared dramatically in the gamma-ray range without any coincident increase in the X-ray emission, providing the first unambiguous example of an "orphan'' gamma-ray flare from a blazar. The gamma-ray spectrum for these data can also be described by a simple power-law fit with alpha = 2.82 +/- 0.15(stat) +/- 0.30(sys). There is no compelling evidence for spectral variability or for any cutoff to the spectrum.


bl lacertae objects : individual (1es 1959+650);; gamma rays : observations;; techniques : spectroscopic;; cherenkov telescopes;; strong flares;; tev energies;; radiation;; system;; markarian-421;; calibration;; h1426+428;; project

Date of this Version

January 2005



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