  PKS 1510-089 (z=0.361) is one of only a handful of flat spectrum radio
quasars that have been detected at very high energy (VHE, $E>100\,$GeV) gamma
rays. It is a very active source across the entire electromagnetic spectrum.
VHE observations in May 2016 with H.E.S.S. and MAGIC revealed an exceptionally
strong flare, which lasted for less than two nights, and exhibited a peak flux
of about 0.8 times the flux of the Crab Nebula above $200\,$GeV. The flare
provides the first evidence of intranight variability at VHE in this source.
While optical observations with ATOM reveal a counterpart at optical
frequencies, Fermi-LAT observations reveal only low flux variability at high
energy (HE, $E>100\,$ MeV) gamma rays. Interestingly, the HE spectral index
significantly hardens during the peak of the VHE flare, indicating a strong
shift of the peak frequency of the high energy component. Given the expected
strong absorption due to the broad-line region, the VHE emission region cannot
be located deep within that region.
