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16 results on '"Commichau, S"'

1. FACT -- the First Cherenkov Telescope using a G-APD Camera for TeV Gamma-ray Astronomy (HEAD 2010)

Author

Anderhub, H., Backes, M., Biland, A., Boller, A., Braun, I., Bretz, T., Commichau, S., Commichau, V., Domke, M., Dorner, D., Gendotti, A., Grimm, O., von Gunten, H., Hildebrand, D., Horisberger, U., Köhne, J. -H., Krähenbühl, T., Kranich, D., Krumm, B., Lorenz, E., Lustermann, W., Mannheim, K., Neise, D., Pauss, F., Renker, D., Rhode, W., Rissi, M., Ribordy, M., Röser, U., Stark, L. S., Stucki, J. -P., Tibolla, O., Viertel, G., Vogler, P., Warda, K., and Weitzel, Q.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Geiger-mode Avalanche Photodiodes (G-APD) bear the potential to significantly improve the sensitivity of Imaging Air Cherenkov Telescopes (IACT). We are currently building the First G-APD Cherenkov Telescope (FACT) by refurbishing an old IACT with a mirror area of 9.5 square meters and construct a new, fine pixelized camera using novel G-APDs. The main goal is to evaluate the performance of a complete system by observing very high energy gamma-rays from the Crab Nebula. This is an important field test to check the feasibility of G-APD-based cameras to replace at some time the PMT-based cameras of planned future IACTs like AGIS and CTA. In this article, we present the basic design of such a camera as well as some important details to be taken into account., Comment: Poster shown at HEAD 2010, Big Island, Hawaii, March 1-4, 2010

Published
2010

2. MAGIC observation of the GRB080430 afterglow

Author

MAGIC Collaboration, Aleksić, J., Anderhub, H., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Balestra, S., Barrio, J. A., Bastieri, D., González, J. Becerra, Becker, J. K., Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. de Cea, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fernández, E., Firpo, R., Fonseca, M. V., Font, L., Galante, N., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Goebel, F., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paoletti, R., Paredes, J. M., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Strah, N., Struebig, J. C., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Tescaro, D., Teshima, M., Torres, D. F., Turini, N., Vankov, H., Wagner, R. M., Zabalza, V., Zandanel, F., Zanin, R., Zapatero, J., and de Ugarte-Postigo, A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Context: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment. Aim: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at $\sim 100$\,GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies. Methods: We used the results of the MAGIC telescope observation of the moderate resdhift ($z\sim0.76$) \object{GRB\,080430} at energies above about 80\,GeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes. Results: We obtained an upper limit of $F_{\rm 95%\,CL} = 5.5 \times 10^{-11}$\,erg\,cm$^{-2}$\,s$^{-1}$ for the very-high energy emission of \object{GRB\,080430}, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift ($z \lesssim 0.8$), provided the observations are carried out at early times, close to the onset of their afterglow phase., Comment: 6 pages, 1 figure. Astronomy & Astrophysics, in press. Revision affects only the author list.

Published
2010
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3. Search for an extended VHE gamma-ray emission from Mrk 421 and Mrk 501 with the MAGIC Telescope

Author

MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fonseca, M. V., Font, L., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paiano, S., Paoletti, R., Paredes, J. M., Partini, S., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Struebig, J. C., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Torres, D. F., Vankov, H., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Neronov, A., and Semikoz, D. V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Context: Part of the very high energy $\gamma$-ray radiation coming from extragalactic sources is absorbed through the pair production process on the extragalactic background light photons. Extragalactic magnetic fields alter the trajectories of these cascade pairs and, in turn, convert cosmic background photons to gamma-ray energies by inverse Compton scattering. These secondary photons can form an extended halo around bright VHE sources. Aims: We searched for an extended emission around the bright blazars Mrk 421 and Mrk 501 using the MAGIC telescope data. Methods: If extended emission is present, the angular distribution of reconstructed gamma-ray arrival directions around the source is broader than for a point-like source. In the analysis of a few tens of hours of observational data taken from Mrk 421 and Mrk 501 we used a newly developed method that provides better angular resolution. This method is based on the usage of multidimensional decision trees. Comparing the measured shapes of angular distributions with those expected from a point-like source one can detect or constrain possible extended emission around the source. We also studied the influence of different types of systematic errors on the shape of the distribution of reconstructed gamma-ray arrival directions for a point source. Results: We present upper limits for an extended emission calculated for both sources for various source extensions and emission profiles. We discuss possible constraints on the extragalactic magnetic fields strength. We obtain upper limits on the extended emission around the Mrk~421 (Mrk~501) on the level of < 5% (< 4%) of the Crab Nebula flux above the energy threshold of 300 GeV. Using these results we discuss possible constraints on the extragalactic magnetic fields strength around a few times $10^{-15}$~G., Comment: 8 pages, 9 figures, accepted for publication in A&A

Published
2010
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4. Gamma-ray excess from a stacked sample of high- and intermediate-frequency peaked blazars observed with the MAGIC telescope

Author

MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fonseca, M. V., Font, L., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E, Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paiano, S., Paoletti, R., Paredes, J. M., Partini, S., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J, Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Struebig, J. C., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Tibolla, O., Torres, D. F., Vankov, H., Wagner, R. M., Weitzel, Q., Zabalza, V, Zandanel, F., and Zanin, R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Between 2004 and 2009 a sample of 28 X-ray selected high- and intermediate-frequency peaked blazars with a X-ray flux larger than 2 uJy at 1 keV in the redshift range from 0.018 to 0.361 was observed with the MAGIC telescope at energies above 100 GeV. Seven among them were detected and the results of these observations are discussed elsewhere. Here we concentrate on the remaining 21 blazars which were not detected during this observation campaign and present the 3 sigma (99.7 %) confidence upper limits on their flux. The individual flux upper limits lie between 1.6 % and 13.6 % of the integral flux from the Crab Nebula. Applying a stacking method to the sample of non-detections with a total of 394.1 hours exposure time, we find evidence for an excess with a cumulative significance of 4.9 standard deviations. It is not dominated by individual objects or flares, but increases linearly with the observation time as for a constant source with an integral flux level of ~1.5 % of that observed from the Crab Nebula above 150 GeV., Comment: 14 pages, 6 figures, accepted by ApJ

Published
2010
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5. MAGIC TeV Gamma-Ray Observations of Markarian 421 during Multiwavelength Campaigns in 2006

Author

MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Balestra, S., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, Mendez, C. Delgado, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fonseca, M. V., Font, L., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paiano, S., Paoletti, R., Paredes, J. M., Partini, S., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Struebig, J. C., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Torres, D. F., Vankov, H., Wagner, R. M., Zabalza, V., Zandanel, F., and Zanin, R.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Major Atmospheric Gamma Imaging Cerenkov (MAGIC) telescope participated in three multiwavelength (MWL) campaigns, observing the blazar Markarian (Mkn) 421 during the nights of 2006 April 28, 29, and 2006 June 14. We analyzed the corresponding MAGIC very-high energy observations during 9 nights from 2006 April 22 to 30 and on 2006 June 14. We inferred light curves with sub-day resolution and night-by-night energy spectra. A strong gamma-ray signal was detected from Mkn 421 on all observation nights. The flux (E > 250 GeV) varied on night-by-night basis between (0.92+-0.11)10^-10 cm^-2 s^-1 (0.57 Crab units) and (3.21+-0.15)10^-10 cm^-2 s^-1 (2.0 Crab units) in 2006 April. There is a clear indication for intra-night variability with a doubling time of 36+-10(stat) minutes on the night of 2006 April 29, establishing once more rapid flux variability for this object. For all individual nights gamma-ray spectra could be inferred, with power-law indices ranging from 1.66 to 2.47. We did not find statistically significant correlations between the spectral index and the flux state for individual nights. During the June 2006 campaign, a flux substantially lower than the one measured by the Whipple 10-m telescope four days later was found. Using a log-parabolic power law fit we deduced for some data sets the location of the spectral peak in the very-high energy regime. Our results confirm the indications of rising peak energy with increasing flux, as expected in leptonic acceleration models., Comment: 11 pages, 7 figures, accepted for publication by Astron. Astrophys

Published
2010
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6. A novel camera type for very high energy gamma-ray astronomy based on Geiger-mode avalanche photodiodes

Author

Anderhub, H., Backes, M., Biland, A., Boller, A., Braun, I., Bretz, T., Commichau, S., Commichau, V., Dorner, D., Gendotti, A., Grimm, O., von Gunten, H., Hildebrand, D., Horisberger, U., Krähenbühl, T., Kranich, D., Lorenz, E., Lustermann, W., Mannheim, K., Neise, D., Pauss, F., Renker, D., Rhode, W., Rissi, M., Röser, U., Rollke, S., Stark, L. S., Stucki, J. -P., Viertel, G., Vogler, P., and Weitzel, Q.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Geiger-mode avalanche photodiodes (G-APD) are promising new sensors for light detection in atmospheric Cherenkov telescopes. In this paper, the design and commissioning of a 36-pixel G-APD prototype camera is presented. The data acquisition is based on the Domino Ring Sampling (DRS2) chip. A sub-nanosecond time resolution has been achieved. Cosmic-ray induced air showers have been recorded using an imaging mirror setup, in a self-triggered mode. This is the first time that such measurements have been carried out with a complete G-APD camera., Comment: 9 pages with 11 figures

Published
2009
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7. Simultaneous multi-frequency observation of the unknown redshift blazar PG 1553+113 in March-April 2008

Author

MAGIC Collaboration, Aleksić, J., Anderhub, H., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Balestra, S., Barrio, J. A., Bastieri, D., González, J. Becerra, Becker, J. K., Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. de Cea, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Mendez, C. Delgado, Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fernández, E., Firpo, R., Fonseca, M. V., Font, L., Galante, N., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Goebel, F., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paoletti, R., Paredes, J. M., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Strah, N., Struebig, J. C., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Tescaro, D., Teshima, M., Torres, D. F., Turini, N., Vankov, H., Wagner, R. M., Zabalza, V., Zandanel, F., Zanin, R., Zapatero, J., Pian, E., Bianchin, V., D'Ammando, F., Di Cocco, G., Fugazza, D., Ghisellini, G., Kurtanidze, O. M., Raiteri, C. M., Tosti, G., Treves, A., Vercellone, S., and Villata, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The blazar PG 1553+113 is a well known TeV gamma-ray emitter. In this paper, we determine its spectral energy distribution using simultaneous multi-frequency data in order to study its emission processes. An extensive campaign was carried out between March and April 2008, where optical, X-ray, high-energy (HE) gamma-ray, and very-high-energy (VHE) gamma-ray data were obtained with the KVA, Abastumani, REM, RossiXTE/ASM, AGILE and MAGIC telescopes, respectively. This is the first simultaneous broad-band (i.e., HE+VHE) gamma-ray observation, though AGILE did not detect the source. We combine data to derive source's spectral energy distribution and interpret its double peaked shape within the framework of a synchrotron self compton model, Comment: 5 pages, 2 figures, published

Published
2009
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8. Correlated X-ray and Very High Energy emission in the gamma-ray binary LS I +61 303

Author

The MAGIC Collaboration, Anderhub, H., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Balestra, S., Barrio, J. A., Bastieri, D., González, J. Becerra, Becker, J. K., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Bigas, O. Blanch, Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. de Cea, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Mendez, C. Delgado, Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fernández, E., Firpo, R., Fonseca, M. V., Font, L., Galante, N., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Goebel, F., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paoletti, R., Paredes, J. M., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Robert, A., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schweizer, T., Shayduk, M., Shore, S. N., Sidro, N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Stark, L. S., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Tescaro, D., Teshima, M., Torres, D. F., Turini, N., Vankov, H., Wagner, R. M., Zabalza, V., Zandanel, F., Zanin, R., Zapatero, J., Falcone, A., Vetere, L., Gehrels, N., Trushkin, S., Dhawan, V., and Reig, P.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The discovery of very high energy (VHE) gamma-ray emitting X-ray binaries has triggered an intense effort to better understand the particle acceleration, absorption, and emission mechanisms in compact binary systems, which provide variable conditions along eccentric orbits. Despite this, the nature of some of these systems, and of the accelerated particles producing the VHE emission, is unclear. To answer some of these open questions, we conducted a multiwavelength campaign of the VHE gamma-ray emitting X-ray binary LS I +61 303 including the MAGIC telescope, XMM-Newton, and Swift during 60% of an orbit in 2007 September. We detect a simultaneous outburst at X-ray and VHE bands, with the peak at phase 0.62 and a similar shape at both wavelengths. A linear fit to the simultaneous X-ray/VHE pairs obtained during the outburst yields a correlation coefficient of r=0.97, while a linear fit to all simultaneous pairs provides r=0.81. Since a variable absorption of the VHE emission towards the observer is not expected for the data reported here, the correlation found indicates a simultaneity in the emission processes. Assuming that they are dominated by a single particle population, either hadronic or leptonic, the X-ray/VHE flux ratio favors leptonic models. This fact, together with the detected photon indices, suggests that in LS I +61 303 the X-rays are the result of synchrotron radiation of the same electrons that produce VHE emission as a result of inverse Compton scattering of stellar photons., Comment: To appear in The Astrophysical Journal Letters. 6 pages, 2 figures

Published
2009
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9. MAGIC Gamma-ray Telescope Observation of the Perseus Cluster of Galaxies: implications for cosmic rays, dark matter, and NGC1275

Author

The MAGIC Collaboration, Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Balestra, S., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Mendez, C. Delgado, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fonseca, M. V., Font, L., Galante, N., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Krähenbühl, T., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paiano, S., Paoletti, R., Paredes, J. M., Partini, S., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Struebig, J. C., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Torres, D. F., Vankov, H., Wagner, R. M., Zabalza, V., Zandanel, F., Zanin, R., Zapatero, J., Pfrommer, C., Pinzke, A., Enßlin, T. A., Inoue, S., and Ghisellini, G.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hr during 2008 November and December. The resulting upper limits on the gamma-ray emission above 100 GeV are in the range of 4.6 to 7.5 x 10^{-12} cm^{-2} s^{-1} for spectral indices from -1.5 to -2.5, thereby constraining the emission produced by cosmic rays, dark matter annihilations, and the central radio galaxy NGC1275. Results are compatible with cosmological cluster simulations for the cosmic-ray-induced gamma-ray emission, constraining the average cosmic ray-to-thermal pressure to <4% for the cluster core region (<8% for the entire cluster). Using simplified assumptions adopted in earlier work (a power-law spectrum with an index of -2.1, constant cosmic ray-to-thermal pressure for the peripheral cluster regions while accounting for the adiabatic contraction during the cooling flow formation), we would limit the ratio of cosmic ray-to-thermal energy to E_CR/E_th<3%. The upper limit also translates into a level of gamma-ray emission from possible annihilations of the cluster dark matter (the dominant mass component) that is consistent with boost factors of ~10^4 for the typically expected dark matter annihilation-induced emission. Finally, the upper limits obtained for the gamma-ray emission of the central radio galaxy NGC1275 are consistent with the recent detection by the Fermi-LAT satellite. Due to the extremely large Doppler factors required for the jet, a one-zone synchrotron self-Compton model is implausible in this case. We reproduce the observed spectral energy density by using the structured jet (spine-layer) model which has previously been adopted to explain the high-energy emission of radio galaxies., Comment: 15 pages, 5 figures; accepted for publication in ApJ; updated to match the journal final version

Published
2009
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10. MAGIC Collaboration: Contributions to the 31st International Cosmic Ray Conference (ICRC 2009)

Author

The MAGIC Collaboration, Anderhub, H., Antonelli, L. A., Antoranz, P., Backes, M., Baixeras, C., Balestra, S., Barrio, J. A., Bastieri, D., González, J. Becerra, Becker, J. K., Bednarek, W., Berger, K., Bernardini, E., Biland, A., Bock, R. K., Bonnoli, G., Bordas, P., Tridon, D. Borla, Bosch-Ramon, V., Bose, D., Braun, I., Bretz, T., Britzger, D., Camara, M., Carmona, E., Carosi, A., Colin, P., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. de Cea, Mendez, C. Delgado, Reyes, R. De los, De Lotto, B., De Maria, M., De Sabata, F., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Errando, M., Ferenc, D., Fernández, E., Firpo, R., Fonseca, M. V., Font, L., Galante, N., López, R. J. García, Garczarczyk, M., Gaug, M., Godinovic, N., Goebel, F., Hadasch, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Hsu, C. C., Jogler, T., Klepser, S., Kranich, D., La Barbera, A., Laille, A., Leonardo, E., Lindfors, E., Lombardi, S., Longo, F., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moles, M., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., Orito, R., Oya, I., Paoletti, R., Paredes, J. M., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R. G., Perez-Torres, M. A., Persic, M., Peruzzo, L., Prada, F., Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribó, M., Rico, J., Rissi, M., Robert, A., Rügamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sánchez-Conde, M., Satalecka, K., Scalzotto, V., Scapin, V., Schweizer, T., Shayduk, M., Shore, S. N., Sierpowska-Bartosik, A., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Stark, L. S., Suric, T., Takalo, L., Tavecchio, F., Temnikov, P., Tescaro, D., Teshima, M., Torres, D. F., Turini, N., Vankov, H., Wagner, R. M., Zabalza, V., Zandanel, F., Zanin, R., and Zapatero, J.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Index entry listing the contributed papers of the MAGIC collaboration to the 31th International Cosmic Ray Conference (ICRC 2009), July 7-15 2009, \L\'od\'z, Poland. The individual papers are sorted by subject: Overview and Highlight Papers; MAGIC-II Status and Components; Software and Analysis Techniques; Technical Developments; Scientific Results. This HTML document includes clickable links to the papers that exist on the astro-ph arXiv. We hope that this will make it easy to access the MAGIC contributions in a systematic way., Comment: Index of the MAGIC conference proceedings for ICRC 2009. Added 6 papers missing in v1

Published
2009

11. Monte Carlo Studies of Geomagnetic Field Effects on the Imaging Air Cherenkov Technique for the MAGIC Telescope Site

Author

Commichau, S. C., Biland, A., Contreras, J. L., Reyes, R. de los, Moralejo, A., Sitarek, J., and Sobczynska, D.

Subjects
Astrophysics
Abstract

Imaging air Cherenkov telescopes (IACTs) detect the Cherenkov light from extensive air showers (EAS) initiated by very high energy (VHE) gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is vital. The influence of the geomagnetic field (GF) on the development of EAS can further complicate the imaging air Cherenkov technique. The amount and the angular distribution of Cherenkov light from EAS can be obtained by means of Monte Carlo (MC) simulations. Here we present the results from dedicated MC studies of GF effects on images from gamma-ray initiated EAS for the MAGIC telescope site, where the GF strength is ~40 micro Tesla. The results from the MC studies suggest that GF effects degrade not only measurements of very low energy gamma-rays below ~100 GeV but also those at TeV-energies., Comment: minor text changes

Published
2008
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12. The MAGIC Project: Contributions to ICRC 2007

Author

Albert, J., Aliu, E., Anderhub, H., Antoranz, P., Armada, A., Baixeras, C., Barrio, J. A., Bartko, H., Bastieri, D., Becker, J. K., Bednarek, W., Berger, K., Bigongiari, C., Biland, A., Bock, R. K., Bordas, P., Bosch-Ramon, V., Bretz, T., Britvitch, I., Cabras, G., Camara, M., Carmona, E., Chilingarian, A., Coarasa, J. A., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Curtef, V., Danielyan, V., Dazzi, F., De Angelis, A., Delgado, C., Reyes, R. de los, De Lotto, B., De Maria, M., De Sabata, F., Dorner, D., Doro, M., Errando, M., Fagiolini, M., Ferenc, D., Fernández, E., Firpo, R., Flix, J., Fonseca, M. V., Font, L., Fuchs, M., Galante, N., García-López, R. J., Garczarczyk, M., Gaug, M., Giller, M., Goebel, F., Hakobyan, D., Hayashida, M., Hengstebeck, T., Herrero, A., Höhne, D., Hose, J., Hsu, C. C., Jacon, P., Jogler, T., Kosyra, R., Kranich, D., Kritzer, R., Laille, A., Lindfors, E., Lombardi, S., Longo, F., López, J., López, M., Lorenz, E., Majumdar, P., Maneva, G., Mannheim, K., Mansutti, O., Mariotti, M., Martínez, M., Mazin, D., Merck, C., Meucci, M., Meyer, M., Miranda, J. M., Mirzoyan, R., Mizobuchi, S., Moralejo, A., Nieto, D., Nilsson, K., Ninkovic, J., na-Wilhelmi, E. O, Otte, N., Oya, I., Paneque, D., Paoletti, R., Paredes, J. M., Pasanen, M., Pascoli, D., Pauss, F., Pegna, R., Persic, M., Peruzzo, L., Piccioli, A., Prandini, E., Puchades, N., Raymers, A., Rhode, W., Ribó, M., Rico, J., Rissi, M., Robert, A., Rügamer, S., Saggion, A., Saito, T. Y., Sánchez, A., Sartori, P., Scalzotto, V., Scapin, V., Schmitt, R., Schweizer, T., Shayduk, M., Shinozaki, K., Shore, S. N., Sidro, N., Sillanpää, A., Sobczynska, D., Spanier, F., Stamerra, A., Stark, L. S., Takalo, L., Temnikov, P., Tescaro, D., Teshima, M., Torres, D. F., Turini, N., Vankov, H., Venturini, A., Vitale, V., Wagner, R. M., Wibig, T., Wittek, W., Zandanel, F., Zanin, R., and Zapatero, J.

Subjects
Astrophysics
Abstract

The MAGIC Project: Contributions to ICRC 2007, Merida, Mexico. Contents pages for the Contribution on behalf of the MAGIC Collaboration to the 30th ICRC that took place in July 2007 in Merida, Mexico. The contents are in html form with clickable links to the papers that exist on the Astrophysics archive. We hope that this will make it easier to access the output of the conference in a systematic way. Comments on how useful this is/ how it could be improved should be sent to michela.demaria@iuav.it., Comment: HTML file with clickable links to papers

Published
2007

13. Geomagnetic Field Effects on the Imaging Air Shower Cherenkov Technique

Author

Commichau, S. C., Biland, A., Kranich, D., Reyes, R. de los, Moralejo, A., and Sobczynska, D.

Subjects
Astrophysics
Abstract

Imaging Air Cherenkov Telescopes (IACTs) detect the Cherenkov light flashes of Extended Air Showers (EAS) triggered by very high energy (VHE) gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is rather difficult, in particular at energies below 100 GeV. The influence of the Geomagnetic Field (GF) on the EAS development can further complicate this discrimination and, in addition, also systematically affect the gamma efficiency and energy resolution of an IACT. Here we present the results from dedicated Monte Carlo (MC) simulations for the MAGIC telescope site. Additionally we show that measurements of sub-TeV gamma-rays from the Crab nebula are affected even for a low GF strength of less than 33 micro Tesla., Comment: Contribution to the 30th ICRC, Merida Mexico, July 2007 on behalf of the MAGIC Collaboration Changes: corrected typos, changed content (figure 1)

Published
2007

14. MAGIC upper limits on the very high energy emission from GRBs

Author

Albert, J., Aliu, E., Anderhub, H., Antoranz, P., Armada, A., Baixeras, C., Barrio, J. A., Bartko, H., Bastieri, D., Becker, J., Bednarek, W., Berger, K., Bigongiari, C., Biland, A., Bock, R. K., Bordas, P., Bosch-Ramon, V., Bretz, T., Britvitch, I., Camara, M., Carmona, E., Chilingarian, A., Ciprini, S., Coarasa, J. A., Commichau, S., Contreras, J. L., Cortina, J., Costado, M. T., Curtef, V., Danielyan, V., Dazzi, F., De Angelis, A., Delgado, C., Reyes, R. de los, De Lotto, B., Domingo-Santamaria, E., Dorner, D., Doro, M., Errando, M., Fagiolini, M., Ferenc, D., Fernandez, E., Firpo, R., Flix, J., Fonseca, M. V., Font, L., Fuchs, M., Galante, N., Garcia-Lopez, R., Garczarczyk, M., Gaug, M., Giller, M., Goebel, F., Hakobyan, D., Hayashida, M., Hengstebeck, T., Herrero, A., Hohne, D., Hose, J., and Hsu, C. C.

Subjects
Astrophysics
Abstract

The fast repositioning system of the MAGIC Telescope has allowed during its first data cycle, between 2005 and the beginning of year 2006, observing nine different GRBs as possible sources of very high energy gammas. These observations were triggered by alerts from Swift, HETE-II, and Integral; they started as fast as possible after the alerts and lasted for several minutes, with an energy threshold varying between 80 and 200 GeV, depending upon the zenith angle of the burst. No evidence for gamma signals was found, and upper limits for the flux were derived for all events, using the standard analysis chain of MAGIC. For the bursts with measured redshift, the upper limits are compatible with a power law extrapolation, when the intrinsic fluxes are evaluated taking into account the attenuation due to the scattering in the Metagalactic Radiation Field (MRF)., Comment: 25 pages, 9 figures, final version accepted by ApJ. Changet title to "MAGIC upped limits on the VERY high energy emission from GRBs", re-organized chapter with description of observation, removed non necessaries figures, added plot of effective area depending on zenith angle, added an appendix explaining the upper limit calculation, added some references

Published
2006
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15. Discovery of VHE gamma-ray emission from 1ES1218+30.4

Author

MAGIC collaboration, Albert, J., Aliu, E., Anderhub, H., Antoranz, P., Armada, A., Asensio, M., Baixeras, C., Barrio, J. A., Bartelt, M., Bartko, H., Bastieri, D., Bavikadi, S. R., Bednarek, W., Berger, K., Bigongiari, C., Biland, A., Bisesi, E., Bock, R. K., Bretz, T., Britvitch, I., Camara, M., Chilingarian, A., Ciprini, S., Coarasa, J. A., Commichau, S., Contreras, J. L., Cortina, J., Curtef, V., Danielyan, V., Dazzi, F., De Angelis, A., Reyes, R. de los, De Lotto, B., Domingo-Santamaria, E., Dorner, D., Doro, M., Errando, M., Fagiolini, M., Ferenc, D., Fernandez, E., Firpo, R., Flix, J., Fonseca, M. V., Font, L., Galante, N., Garczarczyk, M., Gaug, M., Giller, M., Goebel, F., Hakobyan, D., Hayashida, M., Hengstebeck, T., Hoehne, D., Hose, J., Jacon, P., Kalekin, O., Kranich, D., Laille, A., Lenisa, T., Liebing, P., and Lindfors, E.

Subjects
Astrophysics
Abstract

The MAGIC collaboration has studied the high peaked BL-Lac object 1ES1218+30.4 at a redshift z = 0.182, using the MAGIC imaging air Cherenkov telescope located on the Canary island of La Palma. A gamma-ray signal was observed with 6.4sigma significance. The differential energy spectrum for an energy threshold of 120GeV can be fitted by a simple power law yielding F_E(E) = (8.1+-2.1)*10^-7 (E/250GeV)^(-3.0+-0.4) TeV^-1 m^-2 s^-1. During the six days of observation in January 2005 no time variability on time scales of days was found within the statistical errors. The observed integral flux above 350GeV is nearly a factor two below the the upper limit reported by the Whipple Collaboration in 2003., Comment: 5 pages, 4 figures, submitted to ApJ

Published
2006
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16. Flux upper limit of gamma-ray emission by GRB050713a from MAGIC Telescope observations

Author

Albert, J., Aliu, E., Anderhub, H., Antoranz, P., Armada, A., Asensio, M., Baixeras, C., Barrio, J. A., Bartelt, M., Bartko, H., Bastieri, D., Bavikadi, R., Bednarek, W., Berger, K., Bigongiari, C., Biland, A., Bisesi, E., Bock, R. K., Bretz, T., Britvitch, I., Camara, M., Chilingarian, A., Ciprini, S., Coarasa, J. A., Commichau, S., Contreras, J. L., Cortina, J., Curtef, V., Danielyan, V., Dazzi, F., De Angelis, A., Reyes, R. de los, De Lotto, B., Domingo-Santamaria, E., Dorner, D., Doro, M., Errando, M., Fagiolini, M., Ferenc, D., Fernandez, E., Firpo, R., Flix, J., Fonseca, M. V., Font, L., Galante, N., Garczarczyk, M., Gaug, M., Giller, M., Goebel, F., Hakobyan, D., Hayashida, M., Hengstebeck, T., Hohne, D., Hose, J., Jacon, P., Kalekin, O., Kranich, D., Laille, A., Lenisa, T., Liebing, P., Lindfors, E., Longo, F., Lopez, J., Lopez, M., Lorenz, E., Lucarelli, F., Majumdar, P., Maneva, G., Mannheim, K., Mariotti, M., Martinez, M., Mase, K., Mazin, D., Meucci, M., Meyer, M., Miranda, J. M., Mirzoyan, R., Mizobuchi, S., Moralejo, A., Nilsson, K., Ona-Wilhelmi, E., Orduna, R., Otte, N., Oya, I., Paneque, D., Paoletti, R., Pasanen, M., Pascoli, D., Pauss, F., Pavel, N., Pegna, R., Persic, M., Peruzzo, L., Piccioli, A., Prandini, E., Rico, J., Rhode, W., Riegel, B., Rissi, M., Robert, A., Rugamer, S., Saggion, A., Sanchez, A., Sartori, P., Scalzotto, V., Schmitt, R., Schweizer, T., Shayduk, M., Shinozaki, K., Shore, S., Sidro, N., Sillanpaa, A., Sobczynska, D., Stamerra, A., Stark, L. S., Takalo, L., Temnikov, P., Tescaro, D., Teshima, M., Tonello, N., Torres, A., Torres, D. F., Turini, N., Vankov, H., Vardanyan, A., Vitale, V., Wagner, R. M., Wibig, T., Wittek, W., and Zapatero, J.

Subjects
Astrophysics
Abstract

The long-duration GRB050713a was observed by the MAGIC Telescope, 40 seconds after the burst onset, and followed up for 37 minutes, until twilight. The observation, triggered by a SWIFT alert, covered energies above ~175 GeV. Using standard MAGIC analysis, no evidence for a gamma signal was found. As the redshift of the GRB was not measured directly, the flux upper limit, estimated by MAGIC, is still compatible with the assumption of an unbroken power-law spectrum extending from a few hundred keV to our energy range., Comment: 14 pages, 4 figures, submitted to ApJ

Published
2006
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