optical astronomy with cerenkov telescopes
DESCRIPTION
Optical Astronomy with Cerenkov telescopes. E. Oña-Wilhelmi 1,2 , O.C. de Jager 1 , J. Cortina 3 , V. Fonseca 2 1 NWU, Potchefstroom, South Africa. 2 UCM, Madrid, Spain. 3 IFAE, Barcelona, Spain. Erice, July 10 th , 2004. Cerenkov telescopes. Advantages. - PowerPoint PPT PresentationTRANSCRIPT
Optical Astronomy with Cerenkov telescopes
E. Oña-Wilhelmi1,2, O.C. de Jager1, J. Cortina3, V. Fonseca2
1 NWU, Potchefstroom, South Africa.2 UCM, Madrid, Spain.3 IFAE, Barcelona, Spain.
Erice, July 10th, 2004
Erice, July 10th, 2004 2
Cerenkov telescopes
1. Huge reflectors, i.g. MAGIC has a 230 m2 mirror: ~3 times more light than a 10 m optical telescope.
2. Very fast light detectors: good for transients.
Advantages
Targets
Pulsar mv
Crab 17
PSR B0540-69 14
Vela 24
PSR B0656+14 25
Geminga 26
AGN mv
Mkn 421 14.0
Mkn 501 14.5
1ES 1959 12.0
1ES 1426 16.5
3C279 18.0
(ms time scale) (1 min-1 hour time scale)
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Cerenkov cameras
1. Digitization of pixel currents (PM).
2. Single Photo Counting (APD or HPD).
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The Optical Central PixelWhy using an optical central pixel?:Contemporary ephemeris for active pulsars
Monitoring of atmospheric conditions
Monitoring of transients (high variability of Active Galaxies)
Test the telescope data acquisition and analysis software
Light of the Night Sky Background
What to do in MAGIC?:
Test in HEGRA-CT1 to detect the Crab Optical Pulsation
HPD testing in progress
de Oña-Wilhelmi et al., astro-ph/0405088
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The HEGRA-CT1 Optical Central Pixel
Detection of the Crab optical pulsation:
- Cerenkov detectors:
Whipple (10 m reflector)
CELESTE (solar farm)
-HEGRA-CT1 (3.5 m diameter reflector)
- Future plan: MAGIC
Srinivisan et al. 1997
De Naurois et al. 2001
10 m2
127 pixels each one 0.25° FOV
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0.1°
0.25°
CT1 central pixel
The HEGRA-CT1 Optical Central Pixel
Pulsed Signal
LONS+Nebula
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• DAQ : PCI NI 6034 E card, 16 analogical inputs, 16 bits resolution
• High pass filter to reduce the background
R=2 M & C=100 pF -> 0.5 ms
The CT1 Central Pixel: PM base and data acquisition
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• Basic Transformations: Inertial Frame (SSB)
• Princeton monthly ephemeris: and derivates and T0
i(t) = (To) + (ti-To) + 1/2! d/dt (ti-To)2
• Periodicity search with statistical method (e.g. 2)
0 (15 Oct) 29.8 Hz
Data analysis
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30.9 Hz = 0
Crab light curve
Nov 8th 2002
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Nov 8th 2002
(Hz)
Crab optical signal in 2 hours
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Application: LONS around CrabCamera point run
LONSnebulapulsed
pulsed
RRR
Rp
Misspointing & PSF
-Tauri:
%69
),(
),(
0
2
0
0
2
0
ddrrG
ddrrGpixelr
1121210)4.06.4( srsmphdFI LONSLONS
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background
backgroundreds
2
Single Photon Count.:
Tx 57Npx
Log
(s)
CT1
MAGIC
MAGIC for single photon count. method
5
200s30s
Sensitivity of the method
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Conclusions
1. We detected the Crab Optical Pulsation in 200 s with a 3.5 m diameter telescope.
2. The detection allowed us to infer the LONS in the galactic anticenter: 2.5 times larger than previous measures done for an extragalactic zone.
3. Next steps: test the same procedure in MAGIC (DC currents)
use an Hybrid Photo Detector (HPD)