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First Analysis Results of the Crab Nebula and Mrk421. M. López Moya U.C.M. Analysis chain Mrk421 Camera rotation study Light Curve Crab Nebula. Analysis chain (1). Calibration and Pedestal substraction Used the standard calibration classes - PowerPoint PPT Presentation
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20 Abr 2004 Udine bootcamp 1
First Analysis Results of the Crab Nebula and Mrk421
M. López MoyaU.C.M.
1. Analysis chain
2. Mrk421• Camera rotation study• Light Curve
3. Crab Nebula
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Analysis chain (1)
• Calibration and Pedestal substraction– Used the standard calibration classes– P,C runs selected by hand: needed a method to
look autmotically for the closer P,C runs to a given D run.
– Pedestal runs seem to work fine, but many problems using calibration runs: many pixels look after calibration.
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• Image cleaning– Lvl1 = 3.0, Lvl2 = 2.5 (one ring)– We started to investigate the dependence of
cleaning cuts, but no conclusive results yet: just that 5:3 seems to work better for the Crab.
– Forseen insland analysis and moun rings rejection, specially to analysis at low energies.
Analysis chain (2)
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• Signal Extraction– We use: MExtractSignal2
• Hillas Paramter cuts– for the time being, only use SIZE, LENGTH,
WIDTH & DIST.– we used static cuts: no dependence with zenith
angle took into accout
Analysis chain (3)
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• Getting the telescope pointing postion– Poiting position stored only in CC reports at a
fixed frecuency– For having it in an event by event base, we
extrapolated it using the arrival time of the event.
Analysis chain (4)
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Analysis of Mkn 421
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• Data Set 15 Feb.2004
Mrk 421 (1)
Type Runs # Events Duration [m]
ON
P
C
D
17457
17458
17206-17456 1.019.354 104
OFF D 17459-17543 401.362 50
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Mrk 421 (2)
• Hillas cuts:
SIZE > 2000
0.1 < LENGTH < 0.3
0.05 < WIDTH < 0.12
0.6 < DIST < 1.4
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Mrk 421 (3)
• Correcting the mispointing: The False Source Plot– We consider as source position, the position at the
maximum in the 2D alpha plot
• Fitting the Alpha Plot– Signal region < 10– Backg. region: between 30 - 90– Fit the Backg. region to a 2nd order polinomial. From it
extrapolate the bg. in the signal region– The significance is calculated according to LiMa
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ON data
OFF data
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• Alpha plot at Src position
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• Alpha plot for SIZE > 3000
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• We get nearly 20 , but a relative broad alpha plot.
• The significance is high enough to split this day into subsamples. This allows:– Study camera rotation: is really the rotation
uniform?– Get the ligth curve for that day
Mrk 421 (4)
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• We divide the whole night (1:45 h) into 10
subsamples
• Now, we don´t apply the camera rotation algorithm.
Mrk 421 : Camera rotation (1)
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Mrk 421: Camera rotation (2)
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• For each of the subsamples, we get the source position and it corresponding alpha plot.
• From each alpha plot, we get the number of excess events, that we plot vs. Time, obtaining the light curve for that night.
Mrk 421: Light curve (1)
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Mrk 421: Light curve (2)
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Mrk 421: Light curve (3)
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• BUT, this light curve depends strongly on:– the binning criterium (binning in RunNumber,
RunTime,...)– the hillas cuts
• Also we check the time stamp
Mrk 421: Light curve (3)
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Mrk 421: Checking timestamp (1)
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Mrk 421: Checking timestamp (2)
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Analysis of the Crab Nebula
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• Data Set 15 Feb.2004
Crab Nebula (1)
Runs Duration [m]
ON 16745-16767
16830-16980
17036-17123
84
OFF 16770-16877
16894-17030
17126-17190
33
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• Alpa plot
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• So far, only analyzed the night: 15 Feb 2004.
• For Mrk 421 seems easy to get a nice signal, without using a detailed calibration or cut optimization. We get around 20 .
• According the light curve, although we see some variation, it is difficult for the time being to relay on it.
• Mrk 421 also quite useful to understand telescope behaviour.
• For the Crab the situation is more complex. Seems that different cuts should be used. We get only about 6 .
Conclusions