The high-frequency peaked BL Lac PKS 2005 - 489 ( z = 0.071 ) was observed in 2003 and 2004 with the H.E.S.S .
stereoscopic array of imaging atmospheric-Cherenkov telescopes in Namibia .
A signal was detected at the 6.7 \sigma level in the 2004 observations ( 24.2 hrs live time ) , but not in the 2003 data set ( 27.3 hrs live time ) .
PKS 2005 - 489 is the first blazar independently discovered by H.E.S.S .
to be an emitter of VHE photons , and only the second such blazar in the Southern Hemisphere .
The integral flux above 200 GeV observed in 2004 is ( 6.9 \pm 1.0 _ { stat } \pm 1.4 _ { syst } ) \times 10 ^ { -12 } cm ^ { -2 } s ^ { -1 } , corresponding to \sim 2.5 % of the flux observed from the Crab Nebula .
The 99 % upper limit on the flux in 2003 , I ( > 200 GeV ) < 5.2 \times 10 ^ { -12 } cm ^ { -2 } s ^ { -1 } , is smaller than the flux measured in 2004 , suggesting an increased level of activity in 2004 .
However , the data show no evidence for significant variability on any time scale less than a year .
An energy spectrum is measured and is characterized by a very soft power law ( photon index of \Gamma = 4.0 \pm 0.4 ) .