1. Markarian 421 with MAGIC telescope Daniel Mazin for the MAGIC Collaboration Max-Planck-Institut für Physik, München mazin@mppmu.mpg.de

2. Outline • The MAGIC telescope • AGN Markarian 421 • Data sample • Analysis status • Conclusion / outlook

3. The MAGIC Telescope • The largest imaging atmospheric Cherenkov Telescope with 236 m2 mirror surface • 3.5° FoV Camera with 576 high-QE PMT’s • Design optimized for: • Low energy threshold E = 30 GeV • Fast repositioning tp < 30 sec Canarian Island La Palma, 2200 m asl

4. Aimo Sillanpaa, NOT AGN Markarian 421 • Right Ascension11:04:27 (h:m:s) Declination: +38:12:32 (deg:m:s) • BL Lac object, z=0.030 (370 MLy) • Mass: 1.9 •108 M • First detected extragalactic TeV -ray source (Punch et al, 1992) • Many known flares, active in 2004 • Well described by SSC models (e.g. Konopelko et al, ApJ,597:851) • Still many correlations not understood

5. + X-calibration of the instruments HEGRA, A&A,410,813 Advantages of simultaneous observations • One experiment: one decade in energy • Two experiments: two decades • Multiwavelength campaigns • Correlation studies • Change hardness during flares (Krennrich et al, ICRC 2003) • Light curves, look for fast flares HEGRA, A&A,393,89

6. MAGIC data sample Sky plot:

7. MAGIC data sample (December 04) • Triggered by RXTE and VERITAS (Dec 14) • After a few hours: MAGIC and HESS agreed to make simultaneous observations • Due to bad weather only 2 days of MAGIC data: 18 and 19 December

8. Comparison of MC predictions and data Good agreement between mc-gamma and excess events

9. Log10(Etrue[GeV]) Log10(Eest[GeV]) Sigma[%] (Eest-Etrue)/Etrue Log10(Eest[GeV]) Estimate of energy resolution • SIZE (total number of PEs) simplest energy estimator • improve energy estimation including other image parameters • optimized estimator using Random Forest technique • 20% (30%) @ 1 TeV (100 GeV)

10. Number of excess events 39.19 Dec (deg) 38.69 38.19 Preliminary 37.69 Preliminary 11.14 11.10 11.07 11.04 11.00 RA (h) Mrk 421: False source plot • For the whole data sample (3.7h): • After cuts: over 700 excess events • Point-like source ( < 0.15 deg )

11. Alpha plots 18/12/05, <Zd>=48 18/12/05, <Zd>=12 • For the 4 samples: Clear signal detection in all of them • Energy range for this analysis: high zenith angle: 250 GeV – 2 TeV low zenith angle: 100 GeV – 1 TeV 19/12/05, <Zd>=51 19/12/05, <Zd>=21

12. Light curve (X-ray) 17-20 December 2004 18/12 19/12 • X-rays: no significant variation • Optical data (KVA): quiescent state Dec 04 Apr 04

13. Light curve (GeV, MAGIC) • Low zenith angle points only, 20 min bins • No strong variations visible • Looks like we just missed the peak of the flare (weather!) 4004 4005 (mjd-49353) • Soon to come: • Energy spectrum and full light curve for the MAGIC data • Combined MAGIC – HESS data analysis

14. Conclusions / Outlook • MAGIC clearly detected a flare of Markarian 421 in December 2004 • Due to bad weather: too late for the peak of the flare • 3.7 hours of data: enough statistics to produce light curves and energy spectra  work in progress • Coordinated ground based Cherenkov telescopes observations going on • Almost full time coverage possible (CANGAROO, HESS, VERITAS, MAGIC) • Up to 3 decades in energy due to energy threshold and different zenith angle conditions

15. Thank you