Search

In this work, we report multi-band flux variability and correlations of the nearby (z=0.031) blazar Markarian 421 (Mrk~421) using multi-wavelength (MWL) data from November 2014 to June 2016. In this period, Mrk~421 exhibited historically low activity in X-rays and very-high-energy gamma rays (VHE; E>0.1 TeV) and an additional spectral component was observed by \textit{Swift}-BAT. The highest flux variability occurs in X-rays and VHE which, despite the low activity, show a significant positive correlation with no time lag. The hardness ratios in the X-rays and VHE γ-rays show the "harder-when-brighter" trend observed in many blazars. Interestingly, the trend flattens at the highest fluxes, which suggests different processes dominating the brightest states. Enlarging our data set with data from the years 2007 to 2014, we measured a positive correlation between the optical and GeV emission centered at zero time lag, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 days centered at a time lag of 43+9/-6 days. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions. In most of the energy bands, the flux distribution follows the Lognormal, rather than the Normal function, indicating that the variability may be dominated by a multiplicative process., PoS: Proceedings of Science, 395, ISSN:1824-8039, 37th International Cosmic Ray Conference (ICRC 2021)

On January 14, 2019, the most energetic photons ever observed from a gamma-ray burst were recorded by the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes, detecting GRB 190114C at TeV energies. We used this unique observation to probe an energy dependence of the speed of light in vacuo for photons, as predicted by several quantum gravity models. From a set of conservative assumptions on the possible intrinsic spectral and temporal evolution, competitive lower limits on the quadratic leading order modification of the speed of light were obtained. We performed the first Lorentz invariance violation test ever performed on a gamma-ray burst signal at TeV energies, which will serve as a stepping stone to future studies., PoS: Proceedings of Science, 395, ISSN:1824-8039, 37th International Cosmic Ray Conference (ICRC 2021)

Certain candidates for the theory of quantum gravity allow violation or deformation of the Lorentz symmetry. This phenomenon, usually referred to as Lorentz invariance violation (LIV), is often modelled by introducing energy-dependent corrections to the standard photon dispersion relation. Modifying terms are expected to be significant at the scale of the Planck energy, and affect photon propagation and interaction. Unfortunately, these effects are vastly below sensitivities of present-day laboratories. However, gamma rays of very high energies, commonly emitted from astrophysical sources, cover astronomical distances on their way to Earth. During this time, the minuscule effects of LIV could sufficiently accumulate to be measured in gamma-ray observatories. In this talk, possible effects of LIV on gamma rays will be reviewed, as well as recent attempts at measuring them. The usual methods of data analysis for tests of LIV will be presented. We will compare and comment on the most prominent results.

Lorentz invariance violation (LIV) is an exciting possible consequence of Quantum Gravity (QG). Detecting and measuring LIV would pose an invaluable input for understanding the nature of QG, and suggest a direction for further development of theoretical models describing it. If Lorentz symmetry is indeed violated, the effects thereof are minuscule, but cumulative. Therefore, very high energy (VHE, E > 100 GeV) gamma rays crossing cosmological distances are excellent probes of LIV. So far, no effects of LIV have been detected, however, it has been strongly constrained. Researchers from three major imaging Cherenkov telescopes (IACTs) experiments (H.E.S.S., MAGIC, and VERITAS) join efforts to perform the most sensitive and robust search for the energy-dependent photon group velocity up to date. It is the first attempt at merging data from different instruments to this purpose, thus creating exceptionally large statistics. Moreover, combining observations from different gamma-ray sources will decrease the influence of source intrinsic effects. In our contribution, we will describe the likelihood-based analysis method developed for this purpose, and present results on simulated data. We will compare impacts of different observations on the overall result, and discuss characteristics of the most influential data samples. In particular, we will focus on the case of GRB 190114C, the only IACT observation of a gamma-ray burst so far whose data was scrutinized for LIV.

On January 14, 2019, the MAGIC telescopes detected GRB 190114C at teraelectronvolt energies, recording the most energetic photons ever observed from a gamma-ray burst. Using this unique observation, we probe energy dependence of the speed of light in vacuo as predicted by several quantum-gravity models. Based on a set of well-justified assumptions on the possible intrinsic spectral and temporal evolution, we obtain competitive lower limits on the quadratic leading order modification of the speed of light. This is the first Lorentz invariance violation (LIV) test ever performed on a gamma-ray burst signal at TeV energies and will serve as a stepping stone to future studies. The results will be put into context of the most stringent bounds on LIV obtained using gamma rays.

The MAGIC collaboration reports the first detection of very-high-energy (VHE ; E>100 GeV) gamma-ray emission from the flaring blazar TXS1515-273 (RA=15 18 03.610, Dec= -27 31 31.40, J2000.0). The object was observed with the MAGIC telescopes for 1.9 hours on 2019/02/28 under moderate moonlight in the zenith distance range 55 - 60 deg. The preliminary real-time analysis of this data shows a detection of TXS1515-273 with a statistical significance more than 5 standard deviations. The MAGIC observations were triggered by the flaring activity reported by Fermi-LAT from 2019/02/24 to 2019/02/25 (ATel#12532). Few hours before that ATel, a communication from Dave Thompson from the Fermi team alerted the MAGIC collaboration about this source. The redshift of this source is uncertain, with an upper limit z

The MAGIC telescopes performed a rapid follow-up observation of GRB 190114C (Gropp et al., GCN 23688 ; Tyurina et al., GCN 23690, de Ugarte Postigo et al., GCN 23692, Lipunov et al. GCN 23693, Selsing et al. GCN 23695). This observation was triggered by the Swift-BAT alert ; we started observing at about 50s after Swift T0: 20:57:03.19. The MAGIC real-time analysis shows a significance >20 sigma in the first 20 min of observations (starting at T0+50s) for energies >300GeV. The relatively high detection threshold is due to the large zenith angle of observations (>60 degrees) and the presence of partial Moon. Given the brightness of the event, MAGIC will continue the observation of GRB 190114C until it is observable tonight and also in the next days. We strongly encourage follow-up observations by other instruments. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) and K. Noda (nodak@icrr.u-tokyo.ac.jp). MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located at the Observatory Roque de los Muchachos on the Canary island La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV.

Certain candidates for the theory of quantum gravity predict a non-trivial dispersion relation for photons, an effect dubbed Lorentz Invariance Violation (LIV). As a consequence, the speed of photons may depend on their energy. This tiny effect might be accumulated for very high energy (VHE, E > 100 GeV) photons crossing cosmological distances, resulting in a different time-of-flight (ToF) compared to low energy photons, presumably emitted simultaneously at the source. Using a flare from the blazar Mrk 421 detected by the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes in 2014, we set the strongest limits so far on the quadratic correction for the dispersion relation of the photon using the ToF method. Moreover, the MAGIC Collaboration recently observed for the first time photons above 200 GeV from the gamma-ray burst GRB 190114C. This is by far the highest energy detected from a GRB. Results of a LIV study on these data will be presented as well.

The MAGIC telescopes have observed an increase in the very-high-energy (VHE ; >100 GeV) gamma-ray flux from a position compatible with the blazar BL Lacertae (RA=22h02m43.3s Dec=+42d16m40s, J2000.0, z=0.07). The preliminary analysis of 0.76 hours of MAGIC data taken on 2019/05/03 (MJD 58606.18 to 58606.20) under zenith angle range from 46 to 53 deg and dark time conditions with the atmospheric transmission of 0.85, indicates a flux larger than 0.1 of the flux from the Crab nebula above 200 GeV, and detection significance over 6 sigma. The MAGIC observations were triggered by the flaring activity at HE gamma-rays reported by Fermi-LAT (ATel #12718), and optical observations by Astronomical Observatory of the University of Siena (ATel #12722). MAGIC observations on BL Lacertae will continue during the next days and multiwavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) and D. Dominis Prester (dijana@phy.uniri.hr) 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.

The MAGIC telescopes have observed an unprecedented level of very-high-energy (VHE ; >100 GeV) gamma-ray flux from 1ES 1218+304 (12h21m21.941s, +30d10m37.11s, J2000.0). The preliminary analysis of the data from 2018/12/31 to 2019/01/02 indicates a VHE gamma-ray flux reaching the level of ~25 % of the flux from the Crab nebula above 100 GeV. Compared to the quiescent state reported by VERITAS, this implies an increase by a factor of ~4. The previous record of VHE gamma-ray flux of this source was ~20% of the flux from the Crab nebula above 100 GeV. It was measured by VERITAS on the night of 30 January 2009 (2010ApJ, 709L, 163A). 1ES 1218+304 is a high-synchrotron-peaked BL Lac object located at redshift z=0.182. It was first recognized as a VHE gamma-ray emitter by the MAGIC Collaboration in 2005 (Albert, J., 2006, ApJ, 642L, 119A). The MAGIC observations were triggered by the flaring activity in the optical R-band, measured by the KVA telescope from 2018/12/24 to 2019/01/02. The KVA data showed a flux of 2.35+/-0.05 mJy on 2019/01/02, which is the highest optical flux measurement from this source in a time span of 15 years (http://users.utu.fi/kani/1m/1ES_1218+304_jy.html). MAGIC observations on 1ES 1218+304 will continue during the next weeks and multiwavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), V. Fallah Ramazani (vafara@utu.fi) and M. Cerruti (matteo.cerruti@icc.ub.edu). 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.

The MAGIC collaboration reports on the first time detection of very-high-energy (VHE ; E>100 GeV) gamma-ray emission from Ton 0599 (RA:+11:59:31.83 DEC:+29:14:43.83, J2000). The object was observed with the MAGIC telescopes for ~1 hour on 2017/12/15 (MJD 58102.2). The preliminary analysis of these data resulted in the detection of Ton 0599 with a statistical significance of about 10 standard deviations. The VHE flux of this detection was estimated to be around 0.15x10^-9 [ph/cm2/s] (corresponding to about 0.3 CU) above 100 GeV, with a soft spectrum. TON599 is a gamma-ray FSRQ at z=0.72 which is in a remarkably high state from optical to gamma-ray since October 2017 (ATel #10931, #10932, #10937, #10938, #10948, #10949). MAGIC observations on TON 0599 will continue during the next days and multi-wavelength observations are strongly encouraged.

We report an enhanced emission of VHE gamma-rays from the direction of the blazar TXS 0506+056 (05 09 25.96370, +05 41 35.3279 (J2000), [Lani et al., Astron. J., 139, 1695-1712 (2010)]), located 6 arcmin from the estimated direction of the high energy IceCube neutrino event IceCube-170922A (ATel #10791). On Dec 3rd 2018 the MAGIC telescopes observed this source for about 2 hours under good weather conditions. The source was detected at VHE gamma-rays above 90 GeV with a significance larger than 5 sigma. The preliminary analysis yields an estimate of the VHE gamma-ray flux above 90 GeV of ~10-15% of the flux from the Crab Nebula above the same energy threshold, and a spectral index of ~4. This flux is consistent with the emission level integrated between September 28th 2017 to October 3rd 2017, when the source was discovered at VHE gamma-rays (ATel #10817). The MAGIC telescopes will continue monitoring the VHE gamma-ray emission of TXS 0506+056. Soft-X-rays and ultraviolet ToO observations with the Neil Gehrels Swift Observatory have been approved for the next three nights (PI: Cerruti, on behalf of MAGIC), to occur within the time-window 00:00 to 04:00 UTC. NuSTAR ToO observations have also been approved (PI: Satalecka). Multi-wavelength observations (quasi)-simultaneous with MAGIC in this time-window are strongly encouraged.

The MAGIC telescopes have observed a strong increase in the very-high-energy (VHE ; >100 GeV) gamma-ray flux from S50716+714 (RA: 7:21:53.45, Dec: 71:20:36.36, J2000.0). MAGIC observed the source for ~2 hours on 2017/12/28. The preliminary analysis of the MAGIC data indicates increasing flux reaching up to 1.5 times the flux of the Crab nebula above 150 GeV, which is ~6 times higher than the VHE flux from this source during the 2015 flare (ATel #6999). S50716+714 is an intermediate Synchrotron peaked blazar (IBL, Giommi et al. 1999, A&A, 351, 59 ; Ackermann et al. 2011, ApJ, 743, 171) located at the redshift of ~0.3 (Nilsson et al., 2008, A&A, 487, L29 ; Danforth et al., 2013, ApJ, 764, 57). VHE gamma-ray emission from S50716+714 was first reported by the MAGIC collaboration during high optical state of the source (Anderhub et al. 2009, ApJ, 704, L129). Observations of MAGIC were triggered by the hard spectrum of the source (spectral index = -1.86 +/- 0.14, Flux (100MeV-300 GeV) = 0.58 +/- 0.12 e-06 ph cm^-2.) found in the Fermi-LAT data in the 24 hour period started on 2017-12-25 at 18:00:00 UTC. MAGIC observations on S50716+714 will continue during the next two nights and possibly after the moon break and multi-wavelength observations are encouraged. The MAGIC contact person for these observations is R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located on 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.

e-ASTROGAM ('enhanced ASTROGAM') is a breakthrough Observatory space mission, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV - the lower energy limit can be pushed to energies as low as 150 keV for the tracker, and to 30 keV for calorimetric detection. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e- ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on the surroundings. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, e-ASTROGAM will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo- GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and LISA.

The MAGIC collaboration reports the first detection of very-high-energy (VHE ; E>100 GeV) gamma-ray emission from PGC 2402248, also known as 2WHSP J073326.7+515354 (Chang et al. 2016, A&A, 598, A17) with coordinates R.A.: 07:33:26.7 h, Dec: +51:53:54.99 deg. The source is classified as an extreme high-energy peaked BL Lacertae object of unknown redshift, included in the 2WHSP catalog with a synchrotron peak located at 10^17.9 Hz. PGC 2402248 was observed with the MAGIC telescopes from 2018/01/23 to 2018/04/18 (MJD 58141-58226) for about 23 h. The preliminary analysis of these data resulted in the detection of PGC 2402248 with a statistical significance of more than 6 standard deviations. The VHE integral flux was estimated to be (2.2 +/- 0.6)e-12 ph cm^-2 s-1 above 200 GeV, corresponding to around 1% of the Crab Nebula flux above the same energy threshold. The source was also observed with the XRT instrument on-board the Neil Gehrels Swift Observatory from 2018/01/26 to 2018/04/08 (MJD 58144-58216) with 7 visits almost contemporaneous to the MAGIC observations. The preliminary analysis performed with the publicly available tools (http://www.swift.ac.uk/results/index.php) shows a hint of flux variability from a minimum count rate of 0.43 (MJD 58164) to a maximum of 0.62 cnt/s during the last observation (MJD 58216), in the 0.3-10 keV range. MAGIC and Swift/XRT observations of PGC 2402248 will continue during the next days and multiwavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), L. Foffano (luca.foffano@phd.unipd.it) and J. Becerra Gonzalez (jbecerra@iac.es). MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located on 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. We would like to thank the Swift Team for making these observations possible.

TON 0599 (z=0.7247) is the latest addition to a limited club of flat spectrum radio quasars (FSRQs) detected in very high energy (VHE, E > 100 GeV) gamma rays. Its redshift makes it the third farthest source, filling the gap in the redshift distribution of the VHE gamma ray emitters. It was detected for the first time with the MAGIC telescopes on 2017/12/15. The observations were triggered by hardening of the high energy (HE, E > 100 MeV) gamma-ray spectrum observed with Fermi-LAT. During 1 hour of observation with the MAGIC telescopes the flux reached about 40 per cent of the Crab Nebula flux above 80 GeV. The observations continued until 2017/12/29, witnessing gradual decrease of the flux. The spectrum in VHE gamma rays connects smoothly to the spectrum in HE obtained from simultaneous observations with Fermi-LAT. The joint spectrum shows sudden drop above about 8 GeV, which may suggest a strong absorption of VHE gamma rays within the source. In addition, we were able to follow the spectral evolution during the fading phase of the flare. We round the multiwavelength picture with observations in optical, IR, and radio bands acquired by the WEBT collaboration during the whole 2017-2018 optical observing season, from November to May.

The astrophysical journal 863(1), L10 (2018). doi:10.3847/2041-8213/aad083, A neutrino with energy ∼290 TeV, IceCube-170922A, was detected in coincidence with the BL Lac object TXS 0506+056 during enhanced gamma-ray activity, with chance coincidence being rejected at ∼3σ level. We monitored the object in the very-high-energy (VHE) band with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes for ∼41 hr from 1.3 to 40.4 days after the neutrino detection. Day-timescale variability is clearly resolved. We interpret the quasi-simultaneous neutrino and broadband electromagnetic observations with a novel one-zone lepto-hadronic model, based on interactions of electrons and protons co-accelerated in the jet with external photons originating from a slow-moving plasma sheath surrounding the faster jet spine. We can reproduce the multiwavelength spectra of TXS 0506+056 with neutrino rate and energy compatible with IceCube-170922A, and with plausible values for the jet power of $\sim 10^{45} - 4 \times 10^{46} erg s^{-1}$. The steep spectrum observed by MAGIC is concordant with internal γγ absorption above ∼100 GeV entailed by photohadronic production of a ∼290 TeV neutrino, corroborating a genuine connection between the multi-messenger signals. In contrast to previous predictions of predominantly hadronic emission from neutrino sources, the gamma-rays can be mostly ascribed to inverse Compton upscattering of external photons by accelerated electrons. The X-ray and VHE bands provide crucial constraints on the emission from both accelerated electrons and protons. We infer that the maximum energy of protons in the jet comoving frame can be in the range $∼10^{14} – 10^{18}$ eV., Published by IOP, Chicago, Ill. [u.a.]

The MAGIC and VERITAS collaborations report a continuing increase in TeV gamma-ray emission from the 50-year period pulsar/ Be-star binary system PSR J2032+4127/ MT91 213 (RA 20h32m13.13s, Dec +41d27m24.4s, J2000.0). The system reached periastron on 13 November 2017. The Swift X-ray flux has dropped dramatically over the past two weeks (see ATEL #10920 and the Swift light curve). MAGIC and VERITAS observations are being conducted as part of a coordinated long-term monitoring campaign. TeV emission associated with the binary was first reported in ATEL #10810, covering observations up to late September 2017. The TeV flux has further increased since then. Preliminary analysis of the most recent observations gives integral fluxes above 200 GeV of 1.9e-11 ± 0.4e-11 photons cm^-2 s^-1 for an observation of 1.9 hours on Nov 12 (MJD 58069.8) with MAGIC. This implies an increase in the flux of almost a factor 10 with respect to the average flux in June-August. The flux measured by VERITAS is also enhanced, at the level of 1.3e-11 ± 0.2e-11 photons cm^-2 s^-1 for 4 hours of observations between Nov 10 and Nov 13. TeV observations with both instruments will continue with highest priority. We strongly encourage multi-wavelength observations.

The VERITAS and MAGIC collaborations report the detection of an enhanced TeV gamma-ray flux from the pulsar/ Be-star binary system PSR J2032+4127/ MT91 213 (RA 20h32m13.13s, Dec +41d27m24.4s, J2000.0). The binary nature of this system was identified in 2015 through radio and gamma-ray timing observations (Lyne et al., MNRAS, 451, 581, 2015). The orbital period is estimated at 45-50 years, with periastron expected to occur around November 2017. The X-ray flux has been steadily increasing as the system approaches periastron (Bird et al., arXiv:1708.04718). PSR J2032+4127 is co-located with the extended TeV gamma-ray source, TeV J2032+4130, and may be physically associated with it. Both VERITAS and MAGIC observations were conducted as part of a coordinated long-term monitoring campaign. The source was observed most recently by VERITAS between 16 September and 27 September 2017 for a total exposure of 15.3 hours. In a preliminary analysis, the integral flux measured by VERITAS above 200 GeV is 4.2e-12 ± 0.7e-12 photons cm^-2 s^-1 (~2% of the Crab Nebula flux), corresponding to approximately twice the flux measured at the same location in archival VERITAS observations from spring 2017. The emission is consistent with a point source at the location of PSR J2032+4127, offset from the center of the previously known extended TeV source. The VERITAS source name is VER J2032+414. The statistical significance of the gamma-ray excess at the pulsar position is 6.8 standard deviations. MAGIC observations comprise 5.6 hours taken between 10 September and 25 September. A preliminary analysis of the MAGIC data indicates a flux of 5.6e-12 ± 1.2e-12 photons cm^-2 s^-1 above 200 GeV, which implies an increase by about a factor of 2 with respect to the mean flux observed by MAGIC in June-August 2017. The MAGIC source name is MAGIC J2032+4127. The gamma-ray flux is predicted to continue to increase over the coming months (e.g. Takata et al., ApJ, 836, 241), and VERITAS and MAGIC observations will continue with highest priority. We strongly encourage coordinated multiwavelength observations.

PKS 1510-089 (z=0.361), one of only a handful of flat spectrum radio quasars (FSRQ) detected in the very high energy (VHE, E > 100 GeV) gamma-rays, is known for its flux variability and complex multiwavelength behaviour. VHE observations by H.E.S.S. and MAGIC in May 2016 detected an unprecedented flare, both in intensity and in the shortness of its variability timescale. The flare lasted less than 48 hours, during which time the flux reached about 80 per cent of the Crab Nebula flux above 200 GeV. In addition, the intranight variability of this source was detected for the first time. Simultaneous observations in high energy (HE, E > 100 MeV) gamma-rays performed with Fermi-LAT and optical R-band performed with ATOM show behaviour not consistent with simple simultaneous brightening in all bands. While a significant hardening of the spectrum is visible in HE, the flux increased only moderately. A simultaneous rise in daily-averaged optical flux was seen in the R-band. However, the intranight flux evolution shows two prominent peaks, while only one is visible in the VHE range. These intriguing features of the flare will be presented in detail. We will also discuss possible explanations for the observed emission.

The MAGIC telescopes have observed an increase in the very-high-energy (VHE ; >50 GeV) gamma- ray flux from PKS 1424+240, RA: 14:27:00.4 and DEC: +23:48:00, J2000.0 (Wenger, M. et al., 2000, A&AS, v.143, 9). The preliminary analysis of the MAGIC data taken on 2017/03/09, indicates an integral photon flux of (7.6 +/- 2.3) x 10^-11 [cm^-2/s] above 70 GeV. The estimated flux corresponds to 10+/-3 % of the Crab Nebula integral flux above the same energy threshold (70 GeV), and shows a hint of elevated flux in comparison with the previous detections (Archambault, S. et al., 2014, ApJL, 785, 1, L16 and the references therein). PKS 1424+240 is a BL Lac object located at redshift z=0.604 (Paiano et al. 2017, arXiv:1701.04305) and was previously reported as a VHE gamma-ray emitter by VERITAS (Acciari, V.A. et al., 2010, ApJ 708 L100) and MAGIC (Aleksi?, J. et al., 2014, A&A 567, 135). It is the most distant VHE emitter whose source type is confirmed as a BL Lac object. The MAGIC observations were triggered by the hard spectrum in HE gamma-ray band (0.1-300 GeV), estimated from daily analysis of Fermi data, and showing a photon spectral index = -1.47 +/- 0.28 (TS = 25.9) during 2017/03/06 and 2017/03/07. MAGIC will observe PKS 1424+240 tonight and multi- wavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), V. Fallah Ramazani (vafara@utu.fi) and Gaia Vanzo (gvanzo@iac.es). 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.

Using the MAGIC telescopes, we have observed an increase in the very-high-energy (VHE ; >100 GeV) gamma-ray flux from NGC 1275 (3C 84, 03:19:48.16, +41:30:42.10, J2000.0). The preliminary analysis of the MAGIC data taken during the night between 31 December 2016 and 1 January 2017 indicates a flux of about 1.5 times the flux from the Crab nebula (C.U.) above 100 GeV. The flux was nearly 10 times larger than the flare reported in October 2016 (ATel #9689) and about 60 times larger than the low state of the source (Aleksic et al. 2014, A&A, 564, A5). Further observations by MAGIC performed on the night of 2nd to 3rd of January still reveal a flaring state of about 0.7 C.U. above 100 GeV. MAGIC observed the source for 2.4 hours in each of the two nights, 4.8 hours in total. NGC 1275 is a Fanaroff-Riley I radio galaxy located at redshift 0.018 in the Perseus Cluster of galaxies, and was first reported as a VHE gamma-ray emitter in Aleksic et al., 2012 (A&A, 539, L2). It is one of only few radio galaxies detected in the VHE gamma-ray range. MAGIC observations of NGC 1275 will continue during the next days and multi-wavelength observations are encouraged. The MAGIC contact person for these observations is R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.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.

The microquasar Cygnus X-1 displays the two typical soft and hard X-ray states of a black- hole transient. During the latter, Cygnus X-1 shows a one-sided relativistic radio-jet. Recent detection of the system in the high energy (HE ; E >= 60 MeV) gamma-ray range with Fermi-LAT associates this emission with the outflow. Former MAGIC observations revealed a hint of flaring activity in the very high- energy (VHE ; E >= 100 GeV) regime during this X-ray state. We analyze ∼ 97 hr of Cygnus X-1 data taken with the MAGIC telescopes between July 2007 and October 2014. To shed light on the correlation between hard X-ray and VHE gamma rays as previously suggested, we study each main X-ray state separately. We perform an orbital phase-folded analysis to look for variability in the VHE band. Additionally, to place this variability behavior in a multiwavelength context, we compare our results with Fermi-LAT, AGILE, Swift-BAT, MAXI, RXTE- ASM, AMI and RATAN-600 data. We do not detect Cygnus X-1 in the VHE regime. We establish upper limits for each X-ray state, assuming a power-law distribution with photon index GAMMA = 3.2. For steady emission in the hard and soft X-ray states, we set integral upper limits at 95% confidence level for energies above 200 GeV at 2.6 × 10^−12 photons cm^−2 s^−1 and 1.0 × 10^−11 photons cm^−2 s^−1, respectively. We rule out steady VHE gamma-ray emission above this energy range, at the level of the MAGIC sensitivity, originating in the interaction between the relativistic jet and the surrounding medium, while the emission above this flux level produced inside the binary still remains a valid possibility.

The MAGIC collaboration reports on the detection of very high energy (VHE ; E>150 GeV) gamma-ray emission from OT 081 (RA=17 51 32.82, dec=+09 39 00.73, J2000.0 ; also known as PKS 1749+096 and 4C +09.57). OT 081 is a blazar at a red shift of 0.322 (Stickel, Fried, Kuehr 1988, A&A, 191, 16). The preliminary analysis of the MAGIC data taken on 2016 Jul. 24 (observation time: 1.64 hours) resulted in the detection of OT 081 with a statistical significance of 9 standard deviations. From the preliminary analysis, we estimate the VHE flux of this detection is about 8% of the flux from the Crab Nebula in the energy range above 150 GeV. The MAGIC observations were triggered by the observations in the high energy gamma-ray band by the Fermi-LAT, and X-ray and UV Swift (ATel #9260), an optical band flux increase observed by the MAGIC collaboration with a 35cm Celestron telescope at La Palma, and optical observations from other observatories (ATel #9259). MAGIC observations of OT 081 will continue during the following nights, and multi-wavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) and D. Dominis Prester (dijana@phy.uniri.hr). 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.

FACT, MAGIC, VERITAS and Fermi-LAT collaborations report the measurement of a further increase of the gamma-ray flux together with bright X-ray emission seen by Swift-XRT from a position consistent with the high-energy peaked BL Lac type object 1ES 1959+650 (z=0.047, Schachter et al. 1993, ApJ, 412, 541). Enhanced TeV flux was reported by FACT between MJD 57546--57550 (ATel #9139). After a slight decrease within that period, a new maximum in the TeV flux was measured last night between MJD 57552.09 and 57552.25. Within about 2.7 hours of observations, FACT observed a a flux exceeding 2.5 Crab units, with a statistical significance of 16 standard deviations. This is twice the highest flux observed during the high states in the past week. The results of a preliminary automatic quick look analysis are publicly available, where this link: http://fact-project.org/monitoring/index.php?y=2016&m=06&d=12&source=7&timebin=12&plot=month shows the evolution of a nightly binned background subtracted light curve for the last month. These values are corrected neither for the effect of large zenith distance under which the source is observable nor for the amount of night-sky-background light, with both effects decreasing the measured gamma rate. FACT is regularly monitoring 1ES 1959+650. Currently, it is observing the source each night from 02:15 to 05:00 UTC if weather conditions permit. The source has also been monitored daily by the MAGIC telescopes. For the night of MJD 57552, the preliminary flux above 200GeV from automatic analysis is at the level of about 2.5 Crab units. MAGIC will continue observing the source. VERITAS observed the source for 3.5 hours under bright moonlight conditions on MJD 57552. A preliminary analysis of the data shows a strong detection of the source with a statistical significance of about 60 standard deviations, increasing in flux above 300 GeV from about 1.0e-10 cm^-2 s^-1 (80% of the Crab nebula) to a peak of over 2.6e-10 cm^-2 s^-1 (200% of the Crab nebula) at the end of the observing period. Preliminary analysis of Fermi-LAT data indicates that the object’s flux has almost doubled over the past three weeks. The observed gamma-ray flux (E>1GeV) was (1.9+/-0.5) x 10^-8 cm^-2 s^-1 during the week of 23-30 May, and (4.2+/-0.8) x 10^-8 cm^-2 s^-1 during the week of 6-13 May (statistical uncertainty only). The source detection significance (test statistic) for these weeks was 91 and 250, respectively. Monitoring with the X-ray Telescope onboard the Swift satellite (Swift-XRT) shows that the source underwent a strong X-ray flare comparable to that in 2015 November-December. The highest level during the ongoing flare is reached on June 9 with a 0.3-10 keV count rate of 20.50+/-0.15 cts/s which is only by 12% smaller than the highest historical rate recorded on 2015 December 26. Last night, where the observations was split into two orbits, the count rate was 18.55+/-0.15 cts/s, which corresponds to an unabsorbed 0.3-10 keV flux was (7.41-8.13)\times 10^{; ; -10) erg/cm^2/s during the today's observation. Activity in gamma rays and X-rays has been reported over the past 6 months (Atel #8014, #8107, #8148, #8165, #8193, #8289, #8337, #8342, #8468) with a recent increase seen in multiple different wavebands (ATel #9010, #9070, #9121). Coordinated observations among FACT, MAGIC, VERITAS Fermi-LAT and Swift are ongoing. In consideration of the current activity of this source, we encourage multiwavelength observations. For this source, the Fermi LAT contact person is S. Buson (sara.buson@nasa.gov), for FACT is D. Dorner (dorner@astro.uni-wuerzburg.de), for MAGIC is R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), for VERITAS is R. Mukherjee (muk@astro.columbia.edu).

The MAGIC collaboration reports the detection of very high energy (VHE) gamma-ray emission from 1ES 2037+521 (RA 20h39m23.5s, DEC +52d19m50s, J2000.0). The object was observed with the MAGIC telescopes for 11 hours between 2016/09/26 and 2016/09/30. The preliminary analysis of these data resulted in the detection of 1ES 2037+521 with a statistical significance of 5.7 standard deviations. The preliminary VHE flux from these observations was estimated to be about about 6e-12 cm-2 s-1 above 200 GeV, which is about 3% of the flux from the Crab nebula. 1ES 2037+521 is located at redshift 0.053 (Sbarufatti et al., 2006) and classified as a BL Lac candidate in Veron-Cetti & Veron, 2006. Its X-ray and gamma-ray spectra is hard, which suggest this source may be an extreme HBL (Costamante et al. 2001). MAGIC observations on 1ES 2037+521 will continue until October 3rd, and multiwavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de) and V. Fallah Ramazani (vafara@utu.fi). 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.

The MAGIC collaboration reports results from the follow-up observations of IceCube neutrino HESE/EHE 160731A (AMON GCN notice ; http://gcn.gsfc.nasa.gov/notices_amon/6888376_128290.amon ). Follow up observations from other observatories have been reported (ATels: #9294, #9295, #9298, #9301, #9303, GCN: #19743, #19752, #19758, #19760). MAGIC received the AMON GCN alert on Sun Jul 31 01:55:59 2016 UTC, when the reported sky location was not visible from La Palma. The initial EHE alert coordinates were observed by MAGIC on Sun Jul 31 21:25 - 22:47 UTC, at high zenith angle, 45-65 deg. Because of the 3.5 deg. field of view of the MAGIC cameras, these observations encompassed both the initial and revised IceCube alert positions (as reported in the HESE/EHE AMON GCN alert from Mon 01 Aug 16 02:35:54 UT). No significant VHE gamma-ray emission above 600 GeV was detected within the quoted IceCube 50% containment circle, neither from the initial, nor the revised HESE/EHE alert positions. The energy threshold of the analysis performed was higher than expected for this range of zenith angle because of the presence of a sand layer from the Saharan desert (calima), which somewhat deteriorated the atmospheric conditions during the MAGIC observations. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), K.Satalecka (konstancja.satalecka@desy.de) and D. Glawion (Dorit.Glawion@astro.uni-wuerzburg.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.

Using the MAGIC telescopes, we have observed an increase in the very-high-energy (VHE ; >100 GeV) gamma-ray flux from NGC 1275 (3C 84, 03:19:48.16, +41:30:42.10, J2000.0). The preliminary analysis of the MAGIC data taken on 2016 Oct 29 indicates a flux of (8.5 +/- 0.9) x 10^-11 ph/cm^2/s corresponding to 16% of the flux from the Crab nebula (C.U.) above 100 GeV. This implies an increase by a factor of about 5 with respect to the previously measured VHE flux from this object above the same energy threshold. NGC 1275 is a Fanaroff-Riley I radio galaxy located at the red shift 0.018 in the Perseus Cluster of galaxies, and was first reported as a VHE emitter in Aleksic et al., 2012 (A&A, 539, L2). It is one of only a few radio galaxies detected in the VHE range. The typical VHE flux (>100 GeV) of this object is about 3% C.U. (Aleksic et al. 2014, A&A, 564, A5). MAGIC observations of NGC 1275 will continue during the next days and multi-wavelength observations are encouraged. The MAGIC contact persons for these observations are R. Mirzoyan (Razmik.Mirzoyan@mpp.mpg.de), P. Colin (colin@mppmu.mpg.de) and D. Glawion (dorit.glawion@astro.uni-wuerzburg.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.