MAGIC observation of the ANTARES-detected neutrino sky region

The MAGIC telescopes performed follow-up observations in the very high energy band (VHE ; E>100 GeV) of a ~3 degree-diameter sky region centered at the proposed X-ray counterpart of the ANTARES-detected neutrino event (#ATel 7987). MAGIC observed the source under non-optimal conditions due to the large zenith angle (above 60 deg), starting from Sep. 3 at 20:54 UT, 2.5 days after ANTARES detection. Observations were carried out for 6 nights, ending on Sep. 8, and collecting a total on-source exposure of 4 hours. We neither detected significant emission from the location of the X-ray source, nor found any other gamma-ray source within the ~3 degree field of view of MAGIC. The preliminary analysis centered on the proposed X-ray counterpart gave an integral flux upper limit at 95 % c.l. of 4.7e-12 cm-2 s-1 above E>500 GeV, which corresponds to 8% of the Crab Nebula flux above the same energy, assuming a Crab-like spectral index. The nightly light curve above 500 GeV did not show any hint of a transient signal. The MAGIC contact persons for these observations are R. Mirzoyan (razmik.mirzoyan@mpp.mpg.de), A. Carosi (alessandro.carosi@oa-roma.inaf.it), K. Noda (knoda@mppmu.mpg.de) and G. Pedaletti (giovanna.pedaletti@desy.de). MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located at the Canary island of La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV.