data analysis markarian 421 – 14.-15.02.2004 crab nebula – 27.01.2004 crab nebula – 15.02.2004...

Data Analysis

•Markarian 421 – 14.-15.02.2004•Crab Nebula – 27.01.2004•Crab Nebula – 15.02.2004

2 dim plots : false source analysis

Miss-pointing study

Light Curves

Data:

Applied Cuts(David’s Talk)

• 0.12 < LENGTH < 0.32• 0.06 < WIDTH < 0.15• 0.6 < DIST < 1.3• SIZE > 3000 (photons)

Calculate significance: Li&Ma (1983) formula #17 ALPHA(max) = 10 degrees

False source analysis

• Calculate once source independent parameters:

LENGTH, WIDTH, SIZE, etc• For each assumed source position

calculate source dependent parameters: DIST, ALPHA• The movement of the sky (derotation)• The same procedure for ON and OFF

2 dim sky plotCamera coordinates Sky coordinates

2 dim sky plot (N ex)Camera coordinates Sky coordinates

Why is the spot not very narrow?

Center of the camera is not the center of the rotation?

• Divide the ON sample in several sub-samples

• No derotation• Use the whole OFF sample to

calculate significance

Tracking / Miss-pointing

Estimation of the source position in each of the sub-

samples

Several criteria:• Significance• Number of excess events• Alpha plot: signal and background

shape • Alpha plots of the nearby positions

Estimated source positions

First light curve

Markarian 421

Fine binning: 25 samplesNormal spot Abnormal spot (1

run)

Closer look to this sub-sample

2 minutes, 1 Run, no reports in the runbook

First 5633 events Last 5633 events

Following the miss-pointing

Mrk421: 2nd ON sample

• Derotation around the center of the camera

• Displacement from the center of around 0.3 deg

• Roundish spot

Second light curve

Zenith and azimuth angle

Crab: 27th January 2004

Crab: 14th- 15th February 2004

Conclusion / outlook

•All three samples: clear detection

•Weak sources (even Crab!) still difficult to analyze.

•Possible reasons:

miss-pointing

unstable movement

many “dead” pixels

Mrk 421 OFF

ASYMMETRY

Asymmetry: MC photons

73%27%

Asymmetry: MC protons

40%60%

Asymmetry: Mrk 421 ON

44%56%

Asymmetry: Mrk 421 OFF

39%61%

Asymmetry: Crab ON

40%60%

Asymmetry: Crab OFF

38%62%