VERITAS Observations of the Unusual Extragalactic Transient Swift   J164449.3+573451
  We report on very-high-energy ($>$100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the {\it Swift} Observatory and later detected by multiple radio, optical and X-ray observatories. A total exposure of 28 hours was obtained on Swift J164449.3+573451 with VERITAS during 2011 March 28 -- April 15. We do not detect the source and place a differential upper limit on the emission at 500 GeV during these observations of $1.4 \times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ (99% confidence level). We also present time-resolved upper limits and use a flux limit averaged over the X-ray flaring period to constrain various emission scenarios that can accommodate both the radio-through-X-ray emission detected from the source and the lack of detection by VERITAS. 
E. Aliu, T. Arlen, T. Aune, M. Beilicke, W. Benbow, M. B\"ottcher, A.   Bouvier, S. M. Bradbury, J. H. Buckley, V. Bugaev, A...
astro-ph.HE