First Observations with the MAGIC telescope

1. First Observations with the MAGIC telescope Ester Aliu for the MAGIC collaboration International School of CosmicRay Astrophysics, Erice 2nd-13th July 2004

2. Introduction • MAGIC is in commissioning phase until October 2004 • Established TeV sources such as the Crab Nebula, and the blazars Mrk421 and Mrk501 have been observed in order to assess the telescope performance (angular resolution, sensitivity, energy threshold) • The analysis presented in this talk is based in a restricted sub-sample of Crab Nebula and Mrk421

3. Crab Nebula Aharonian et al. 2004 established as a TeV gamma-ray source by Whipple in 1989 steady emitter at TeV energies (standard candle in IACTs) MAGIC can expect interesting physics for Crab Nebula (<50 GeV) - IC peak - Pulsar MAGIC THRESHOLD 30 GeV IC peak

4. Data Sample & Analysis • Three days of Crab Nebula data from March 2004 have been analized: • March 19th: ON: 1h 08’, =[25-50]deg • OFF: 1h 10’, =[31-53]deg • March 21st: ON: 1h 27’, =[26-54]deg • OFF: 1h 24’, =[33-56]deg • March 22nd: ON: 1h 11’, =[31-52]deg • OFF: 1h 36’, =[33-58]deg • TOTAL: ON: 3h 44’ • OFF: 4h 10’ Optimization Cuts: Scaled Hillas (see Daniel and Nadia’s talk)

5. Data Checks Hillas Distributions (Size > 2000 ph) ( Before gamma /hadron separation) Shower Rate vs zenith On data Off data Before image cleaning After image cleaning After Image Cleaning the shower rate shows a linear dependence with the cosine of the zenith angle as it is expected • Excellent On/Off agreement • Signal already visible without cuts in alpha distribution

6. Detection Sky Plot Excess events in the camera On data Off data No Cuts MAGIC Crab Nebula preliminary Size >2000 photons Significance = 15.1 Excesses = 1302 events

7. Crab Stability • A rate of excesses is computed in a run by run basis for the three days • The light curve is compatible with a steady rate • A way to see that our telescope is stable Run by run light curve (Preliminary!!) March 19th March 21st March 22nd

8. Mrk 421 • First extragalactic source found to emit gamma-rays in the TeV range (Whipple, 1992) • Fastest observed flux variations reported from TeV gammas-ray emitters • Flaring state during last months (seen by Whipple, H.E.S.S., RXTE)

9. Data Sample & Analysis • One day of Mrk421 data from February 2004 has been analized: • February 15th: ON: 1h 45’, =[25-50]deg • OFF: 49’, =[31-53]deg Optimization Cuts: Super Cuts (see Daniel and Nadia’s talk)

10. Detection No Cuts Sky Plot Excess events in the camera Size >2000 photons Significance = 25.3 Excesses = 1694 events

11. Conclusions • MAGIC is working • The established TeV sources, Crab Nebula and Mrk421, have been observed and have been detected with high significance by MAGIC during the ongoing commissioning period • These detections have been reached using a short data sample with a conservative imaging analysis which is valid for high energies

12. Outlook • Light Curves and Spectra analysis are being produced and soon will be presented • New methods for gamma/hadron separation will be applied soon • The analysis of low energy events is ongoing • More data of Crab Nebula and Mrk421 are available • Also other sources have been observed and the analysis is in progress