@article {2012ApJ...746...80A, title = {{Detection of the {$\gamma$}-Ray Binary LS I +61{\deg}303 in a Low-flux State at Very High Energy {$\gamma$}-Rays with the MAGIC Telescopes in 2009}}, journal = {The Astrophysical Journal}, volume = {746}, year = {2012}, month = {feb}, pages = {80}, abstract = {We present very high energy (E {\gt} 100 GeV) {$\gamma$}-ray observations of the {$\gamma$}-ray binary system LS I +61{\deg}303 obtained with the MAGIC stereo system between 2009 October and 2010 January. We detect a 6.3{$\sigma$} {$\gamma$}-ray signal above 400 GeV in the combined data set. The integral flux above an energy of 300 GeV is F(E {\gt} 300 GeV) = (1.4 {\plusmn} 0.3$_{stat}$ {\plusmn} 0.4$_{syst}$) {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$, which corresponds to about 1.3\% of the Crab Nebula flux in the same energy range. The orbit-averaged flux of LS I +61{\deg}303 in the orbital phase interval 0.6-0.7, where a maximum of the TeV flux is expected, is lower by almost an order of magnitude compared to our previous measurements between 2005 September and 2008 January. This provides evidence for a new low-flux state in LS I +61{\deg}303. We find that the change to the low-flux state cannot be solely explained by an increase of photon-photon absorption around the compact star.}, keywords = {binaries: general, gamma rays: general, stars: individual: LS I +61{\deg}303, X-rays: binaries, X-rays: individual: LS I +61{\deg}303}, doi = {10.1088/0004-637X/746/1/80}, url = {http://adsabs.harvard.edu/abs/2012ApJ...746...80A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Bosch-Ramon, V. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, A. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2012A\&A...539L...2A, title = {{Detection of very-high energy {$\gamma$}-ray emission from NGC 1275 by the MAGIC telescopes}}, journal = {Astronomy and Astrophysics}, volume = {539}, year = {2012}, month = {mar}, pages = {L2}, abstract = {We report on the detection of very-high energy (VHE, E {\gt} 100 GeV) {$\gamma$}-ray emission from NGC 1275, the central radio galaxy of the Perseus cluster of galaxies. The source has been detected by the MAGIC telescopes with a statistical significance of 6.6{$\sigma$} above 100 GeV in 46 h of stereo observations carried out between August 2010 and February 2011. The measured differential energy spectrum between 70 GeV and 500 GeV can be described by a power law with a steep spectral index of {$\Gamma$} = -4.1 {\plusmn} 0.7$_{stat}$ {\plusmn} 0.3$_{syst}$, and the average flux above 100 GeV is F$_{gamma}$ = (1.3 {\plusmn} 0.2$_{stat}$ {\plusmn} 0.3$_{syst}$) {\times} 10$^{-11}$ cm$^{-2}$ s$^{-1}$. These results, combined with the power-law spectrum measured in the first two years of observations by the Fermi-LAT above 100 MeV, with a spectral index of {$\Gamma$} {\sime} - 2.1, strongly suggest the presence of a break or cut-off around tens of GeV in the NGC 1275 spectrum. The light curve of the source above 100 GeV does not show hints of variability on a month time scale. Finally, we report on the nondetection in the present data of the radio galaxy IC 310, previously discovered by the Fermi-LAT and MAGIC. The derived flux upper limit F$^{U.L.}$$_{gamma}$ ({\gt}300 GeV) = 1.2 {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$ is a factor \~{} 3 lower than the mean flux measured by MAGIC between October 2009 and February 2010, thus confirming the year time-scale variability of the source at VHE.}, keywords = {galaxies: active, galaxies: individual: IC310, galaxies: individual: NGC 1275, galaxies: jets, gamma rays: galaxies}, doi = {10.1051/0004-6361/201118668}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...539L...2A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barres de Almeida, U. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Eisenacher, D. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Gozzini, S.~R. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kadenius, V. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lewandowska, N. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Coto, R. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Niedzwiecki, A. and Nieto, D. and Nilsson, K. and Nowak, N. and Orito, R. and Paiano, S. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puerto Gimenez, I. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Sun, S. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Pfrommer, C. and Pinzke, A.} } @article {2012ApJ...754L..10A, title = {{Detection of VHE {$\gamma$}-Rays from HESS J0632+057 during the 2011 February X-Ray Outburst with the MAGIC Telescopes}}, journal = {The Astrophysical Journal Letters}, volume = {754}, year = {2012}, month = {jul}, pages = {L10}, abstract = {The very high energy (VHE) {$\gamma$}-ray source HESS J0632+057 has recently been confirmed to be a {$\gamma$}-ray binary. The optical counterpart is the Be star MWC 148, and a compact object of unknown nature orbits it every \~{}321 days with a high eccentricity of \~{}0.8. We monitored HESS J0632+057 with the stereoscopic MAGIC telescopes from 2010 October to 2011 March and detected significant VHE {$\gamma$}-ray emission during 2011 February, when the system exhibited an X-ray outburst. We find no {$\gamma$}-ray signal in the other observation periods when the system did not show increased X-ray flux. Thus, HESS J0632+057 exhibits {$\gamma$}-ray variability on timescales of the order of one to two months possibly linked to the X-ray outburst that takes place about 100 days after the periastron passage. Furthermore, our measurements provide for the first time the {$\gamma$}-ray spectrum down to about 140 GeV and indicate no turnover of the spectrum at low energies. We compare the properties of HESS J0632+057 with the similar {$\gamma$}-ray binary LS I +61{\deg}303 and discuss the possible origin of the multi-wavelength emission of the source.}, keywords = {binaries: general, gamma rays: general, stars: individual: MWC 148, X-rays: binaries, X-rays: individual: HESS J0632+057}, doi = {10.1088/2041-8205/754/1/L10}, url = {http://adsabs.harvard.edu/abs/2012ApJ...754L..10A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barres de Almeida, U. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Bosch-Ramon, V. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Eisenacher, D. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido Terrats, D. and Giavitto, G. and Godinovi{\'c}, N. and Gonz{\'a}lez Mu{\~n}oz, A. and Gozzini, S.~R. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Huber, B. and Jankowski, F. and Jogler, T. and Kadenius, V. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lewandowska, N. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Coto, R. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Niedzwiecki, A. and Nieto, D. and Nilsson, K. and Nowak, N. and Orito, R. and Paiano, S. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and M. A. P{\'e}rez-Torres and Persic, M. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puerto Gimenez, I. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Sun, S. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2012ApJ...744L..19K, title = {{Discovery of Two Supernovae in the Nuclear Regions of the Luminous Infrared Galaxy IC 883}}, journal = {The Astrophysical Journal Letters}, volume = {744}, year = {2012}, pages = {L19}, abstract = {We report the discovery of two consecutive supernovae (SNe), 2010cu and 2011hi, located at 0farcs37 (180 pc) and 0farcs79 (380 pc) projected distance, respectively, from the center of the K-band nucleus of the luminous infrared galaxy (LIRG) IC 883. The SNe were discovered in an ongoing near-infrared K-band search for core-collapse SNe in such galaxies using the ALTAIR/NIRI adaptive optics system with laser guide star at the Gemini-North Telescope. These are thus the closest SNe yet discovered to an LIRG nucleus in optical or near-infrared wavelengths. The near-infrared light curves and colors of both SNe are consistent with core-collapse events. Both SNe seem to suffer from relatively low host galaxy extinction suggesting that regardless of their low projected galactocentric distances, they are not deeply buried in the nuclear regions of the host galaxy.}, keywords = {galaxies: individual: IC 883, galaxies: starburst, infrared: galaxies, instrumentation: adaptive optics, supernovae: individual: SN 2010cu SN 2011hi}, doi = {10.1088/2041-8205/744/2/L19}, url = {http://adsabs.harvard.edu/abs/2012ApJ...744L..19K}, author = {Kankare, E. and Mattila, S. and Ryder, S. and V{\"a}is{\"a}nen, P. and Alberdi, A. and Alonso-Herrero, A. and Colina, L. and Efstathiou, A. and Kotilainen, J. and Melinder, J. and M. A. P{\'e}rez-Torres and Romero-Ca{\~n}izales, C. and Takalo, A.} } @article {2012A\&A...539A.118A, title = {{Discovery of VHE {$\gamma$}-ray emission from the BL Lacertae object B3 2247+381 with the MAGIC telescopes}}, journal = {Astronomy and Astrophysics}, volume = {539}, year = {2012}, month = {mar}, pages = {A118}, abstract = {
Aims: We study the non-thermal jet emission of the BL Lac object B3 2247+381 during a high optical state.
Methods: The MAGIC telescopes observed the source during 13 nights between September 30th and October 30th 2010, collecting a total of 14.2 h of good quality very high energy (VHE) {$\gamma$}-ray data. Simultaneous multiwavelength data was obtained with X-ray observations by the Swift satellite and optical R-band observations at the KVA-telescope. We also use high energy {$\gamma$}-ray (HE, 0.1-100 GeV) data from the Fermi satellite.
Results: The BL Lac object B3 2247+381 (z = 0.119) was detected, for the first time, at VHE {$\gamma$}-rays at a statistical significance of 5.6{$\sigma$}. A soft VHE spectrum with a photon index of -3.2 {\plusmn} 0.6 was determined. No significant short term flux variations were found. We model the spectral energy distribution using a one-zone SSC-model, which can successfully describe our data.}, keywords = {BL Lacertae objects: individual: B3 2247+381, galaxies: active}, doi = {10.1051/0004-6361/201117967}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...539A.118A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Kadenius, V. and Weidinger, M. and Buson, S.} } @article {2012A\&A...544A.142A, title = {{Discovery of VHE {$\gamma$}-rays from the blazar 1ES 1215+303 with the MAGIC telescopes and simultaneous multi-wavelength observations}}, journal = {Astronomy and Astrophysics}, volume = {544}, year = {2012}, month = {aug}, pages = {A142}, abstract = {Context. We present the discovery of very high energy (VHE, E {\gt} 100 GeV) {$\gamma$}-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to {$\gamma$}-rays.
Aims: We study the VHE {$\gamma$}-ray emission from 1ES 1215+303 and its relation to the emissions in other wavelengths.
Methods: Triggered by an optical outburst, MAGIC observed the source in 2011 January - February for 20.3 h. The target was monitored in the optical R-band by the KVA telescope that also performed optical polarization measurements. We triggered target of opportunity observations with the Swift satellite and obtained simultaneous and quasi-simultaneous data from the Fermi Large Area Telescope and from the Mets{\"a}hovi radio telescope. We also present the analysis of older MAGIC data taken in 2010.
Results: The MAGIC observations of 1ES 1215+303 carried out in 2011 January - February resulted in the first detection of the source at VHE with a statistical significance of 9.4{$\sigma$}. Simultaneously, the source was observed in a high optical and X-ray state. In 2010 the source was observed in a lower state in optical, X-ray, and VHE, while the GeV {$\gamma$}-ray flux and the radio flux were comparable in 2010 and 2011. The spectral energy distribution obtained with the 2011 data can be modeled with a simple one zone SSC model, but it requires extreme values for the Doppler factor or the electron energy distribution.}, keywords = {BL Lacertae objects: individual: 1ES 1215+303, gamma-rays: galaxies}, doi = {10.1051/0004-6361/201219133}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...544A.142A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Ansoldi, S. and Asensio, M. and Backes, M. and Barres de Almeida, U. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Eisenacher, D. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido Terrats, D. and Gaug, M. and Giavitto, G. and Godinovi{\'c}, N. and Gonz{\'a}lez Mu{\~n}oz, A. and Gozzini, S.~R. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Huber, B. and Jankowski, F. and Jogler, T. and Kadenius, V. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lewandowska, N. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Coto, R. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Niedzwiecki, A. and Nieto, D. and Nilsson, K. and Nowak, N. and Orito, R. and Paiano, S. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and M. A. P{\'e}rez-Torres and Persic, M. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puerto Gimenez, I. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Sun, S. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Berdyugin, A. and Buson, S. and J{\"a}rvel{\"a}, E. and Larsson, S. and L{\"a}hteenm{\"a}ki, A. and Tammi, J.} } @article {2011A\&A...533A.111M, title = {{Detection of jet precession in the active nucleus of M 81}}, journal = {Astronomy and Astrophysics}, volume = {533}, year = {2011}, month = {sep}, pages = {A111}, abstract = {We report on very-long-baseline-interferometry (VLBI) monitoring observations of the low-luminosity active galactic nucleus (LLAGN) in the galaxy M 81 at the frequencies of 1.7, 2.3, 5.0, and 8.4 GHz. The observations reported here are phase-referenced to the supernova SN 1993J (located in the same galaxy) and cover from late 1993 to late 2005. The large amount of available observations allows us to study the stability of the AGN position in the frame of its host galaxy at different frequencies and chromatic effects in the jet morphology, together with their time evolution. The source consists at all frequencies of a slightly resolved core and a small jet extension towards the northeast direction (position angle of \~{}65 degrees) in agreement with previous publications. We find that the position of the intensity peak in the images at 8.4 GHz is very stable in the galactic frame of M 81 (proper motion upper limit about 10 {$μ$}as per year). We confirm previous reports that the peaks at all frequencies are systematically shifted among them, possibly due to opacity effects in the jet as predicted by the standard relativistic jet model. We use this model, under plausible assumptions, to estimate the magnetic field in the jet close to the jet base and the mass of the central black hole. We obtain a black-hole mass of \~{}2 {\times} 10$^{7}$ M$_{\&sun;}$, comparable to estimates previously reported using different approaches, but the magnetic fields obtained are 10$^{3}$-10$^{4}$ times lower than previous estimates. We find that the positions of the cores at 1.7, 2.3, and 5.0 GHz are less stable than that at 8.4 GHz and evolve systematically, shifting southward at a rate of several tens of {$μ$}as per year. The evolution in the jet orientation seems to be related to changes in the inclination of the cores at all frequencies. These results can be interpreted as due to a precessing jet. The evolving jet orientation also seems to be related to a flare in the peak flux densities at 5.0 and 8.4 GHz, which lasts \~{}4 years (from mid 1997 to mid 2001). An increase in the accretion rate of the black hole, and its correlation with the jet luminosity via the disk-jet connection model, seems insufficient to explain this long flare and the simultaneous evolution in the jet orientation. A continued monitoring of the flux density and the jet structure evolution in this LLAGN will be necessary to further confirm our jet precession model.}, keywords = {astrometry, galaxies: active, galaxies: individual: M 81, galaxies: jets, radiation mechanisms: non-thermal, radio continuum: galaxies}, doi = {10.1051/0004-6361/201117211}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...533A.111M}, author = {Mart{\'\i}-Vidal, I. and Marcaide, J.~M. and Alberdi, A. and M. A. P{\'e}rez-Torres and Ros, E. and Guirado, J.~C.} } @article {2010ApJ...723L.207A, title = {{Detection of Very High Energy {$\gamma$}-ray Emission from the Perseus Cluster Head-Tail Galaxy IC 310 by the MAGIC Telescopes}}, journal = {The Astrophysical Journal Letters}, volume = {723}, year = {2010}, month = {nov}, pages = {L207-L212}, abstract = {We report on the detection with the MAGIC telescopes of very high energy (VHE) {$\gamma$}-rays from IC 310, a head-tail radio galaxy in the Perseus galaxy cluster, observed during the interval 2008 November to 2010 February. The Fermi satellite has also detected this galaxy. The source is detected by MAGIC at a high statistical significance of 7.6{$\sigma$} in 20.6 hr of stereo data. The observed spectral energy distribution is flat with a differential spectral index of -2.00 {\plusmn} 0.14. The mean flux above 300 GeV, between 2009 October and 2010 February, (3.1 {\plusmn} 0.5) {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$, corresponds to (2.5 {\plusmn} 0.4)\% of Crab Nebula units. Only an upper limit, of 1.9\% of Crab Nebula units above 300 GeV, was obtained with the 2008 data. This, together with strong hints ({\gt}3{$\sigma$}) of flares in the middle of 2009 October and November, implies that the emission is variable. The MAGIC results favor a scenario with the VHE emission originating from the inner jet close to the central engine. More complicated models than a simple one-zone synchrotron self-Compton (SSC) scenario, e.g., multi-zone SSC, external Compton, or hadronic, may be required to explain the very flat spectrum and its extension over more than three orders of magnitude in energy.}, keywords = {galaxies: active, galaxies: individual: IC 310, gamma rays: galaxies}, doi = {10.1088/2041-8205/723/2/L207}, url = {http://adsabs.harvard.edu/abs/2010ApJ...723L.207A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Camara, M. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and Krause, J. and La Barbera, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Neronov, A. and Pfrommer, C. and Pinzke, A. and Semikoz, D.~V. and MAGIC Collaboration} }