Report of the Working Group Calibration, Monitoring and Site Conveners: Conveners: M. Teshima, B....

Report of the Working GroupReport of the Working GroupCalibration, MonitoringCalibration, Monitoring

and Site and Site

Conveners:Conveners: M. Teshima, B. Khélifi

Members:Members: J. Cortina, R.G. Lopez, M. Gaug, E. Giraud, R. Mirzoyan, P. Mayumdar, M. Mori, V. Mitev, M. Panter, A. Sillampaä, S. Swordy, J.-P. Tavernet, G. Vasileiadis, S. Wagner

Activity:Activity: 5 phone-conferences, email exchanges Draft for the Letter of Intend

Calibration and atmospheric Calibration and atmospheric monitoringmonitoring

B. Khélifi WG Calibration/Monitoring/Site Paris, 02/03/2007

What to calibrate and to monitor?What to calibrate and to monitor?

• Atmospheric monitoring: Extinction coefficient

• Optical components: Mirrors, funnels,

photocathods

• Camera electronics: Gain, flat fielding,

usable pixels, …

gamma-ray

Atmospheric shower

Cheren

kov lig

ht

~ 10 km

~ 1o

~ 120 m

Conversion factor:Conversion factor: # ADC per Cherenkov photons# ADC per Cherenkov photons


Camera performancesCamera performances

• Functioning parameters of the cameras not treated here,

Just the camera characteristics used for the data analysis

• Channel noise– From electronics – From Night Sky Background

No need of specific instrumentation

• Conversion factor: #ADC per photoelectron– Components: efficiency of the integration window,

electronic gains, Photodetector internal gain LED flashers


Camera performances (2)Camera performances (2)

• Flat fielding– Different detection efficiency between channels

Funnels, photocathodsLED flashers

• Usable channels− Malfunctioning reasons depend on camera technology− Big efforts should be done to their identifications

No need of specific instrumentation


Optical componentsOptical components

• Involved components:Mean Photocathod efficiency, mean funnel and mirrors

efficiency

• This global efficiency allows an absolute calibration

Use of muon rings


Atmospheric monitoringAtmospheric monitoring

• Standard weather conditionsMeteo station

• Water vapor and cloud monitoringInfrared radiometers


Atmospheric monitoring (2)Atmospheric monitoring (2)

• Estimation of the optical depth above telescopes:

• Photometric telescope– Continuous monitoring– Cross-check with LIDAR

• Atmosphere profile– Radiosondes: seasonal variations

LIDAR Transmissometer (transmissivity at the ground layers)

TRmodel = 0.5836TRmeas = 0.5830 (3-5 km)

Dust layer

Troposphere/Desert Dust

TRmodel = 0.9498TRmeas = 0.9508 (9-10.4 km)

60°

Results of LIDAR simulations V. Mitev

Cirrus cloud


ConclusionsConclusions

• Draft of the WG has been submitted (8 pages)

• For the Design Study (Working Package 12):– Big efforts on the LIDAR technique to routinely correct

for atmosphere variations Closer work with atmospheric physicists

– Efforts to measure and to use the seasonal atmospheric profile measured by radiosondes

– Apply and test these atmospheric corrections to the data analysis

Candidates for CTA sitesCandidates for CTA sites


Criteria of selectionCriteria of selection

• Altitude above 1.5 km• Small cloud coverage: good nights > 60%• Atmosphere transparent and dry• Latitude around +30° N and -30° S• Facility of site access• Political stability• …


CTA NorthCTA NorthLa Palma Teide So. Utah Hanle Muna Kea

Location (longitude) 17.86 W 112.5 W 78.96ELocation (Lattitude) 28.75 N 37.5 N 32.78NHeight 2200 m 2400 m 1800-3000 4300mRigidity cutoff

Land owner IAC State India GovtAvaliable flat area 300x300m2 2x2km2 10x10 km2 vastType of ground soil, rocks soil, rocks soil,rocksAccess from nearby City (hrs) 1 1 2 6-7 hrsAccess from EU (hrs) 5 5 19 21-22Nearest international airport La Palma Tenerife S.L.C. Delhi

Clear nights (spectroscopic night)/yr 75% 260Photometric nights/yr 190Days with ground fog/yrLight pollution low low low very low

Av summer day /night temp 17 20/10-15CAv winter day / night temp 2 -5/-15C# of days with wind vel (>10m/s) 13 % 19%# of Cyclones and Tornades / 10yr nilAnnual precipitation(mm) 2mmAv summer humidity 10-40% 15-45%Av winter humidity 40-60% 10-40%Av snow depthMaximum snow depth last 10yr

Electric power line Yes NoWater Yes YesHandy/Mobil service Yes NoDistance to high band width internet 0 0

Nearest hotels or lodge (mins) 0 260KmNearest restaurants (mins) 0 260KmNearest hospitals (mins) 90 75Km

Dangerous animals no no noEndemic disease no no noScientific facilities ENO ENO IAOPolitical stubility Stable Stable yes

Sites - Parameters La Palma Teide So. Utah Hanle Muna Kea

Sites - ParametersCTA-North


CTA SouthCTA SouthHESS Woomera Alma Paranal-La Montura (ch)La Silla-Viscachas (ch)El Huesco (ch) Site D (ch)

Location (longitude) 16.5 E 136.786 E 67.75W 70.41 W 70.73 W 68.46 W 69.05 WLocation (Lattitude) 23.26 S 31.099 S 23.00 S 24.66 S 29.25 S 24.32 S 24.25 SHeight 1800 m 160 m 4600-5100m 2635 m 2200-2400m 4300m 3100mRigidity cutoff

Land owner gvmnt State Chile Chile ? ?Avaliable flat area 500kx300k Vast Nearby summits Low slopes Large Too smallType of ground Soil Soil, rocks Soil, rocks Soil, rocksAccess from nearby City (hrs) 2-3 5 2 2 2 4? 3?Access from EU (hrs) 9.5 25 16+3 16+3 16+2 16+3 16+3Nearest international airport Adelaide Calama Antofagasta La Serena Antofagasta Antofagasta

Clear nights (spectroscopic night)/yr 63 % 72 % <80 % 90 % 82 % 0.9xParanal? Paranal?Photometric nights/yr 54 % >63 % 75-80 % 62 % 0.9xParanal? Paranal?Days with ground fog/yr Some SomeLight pollution None None None Very low None

Av summer day /night temp 19 27 5/0C 14C 6C 14CAv winter day / night temp 11 11 -5/-15C 11C -8C 5C# of days with wind vel (>10m/s) 10 % D:frequent N:rare 25 % 15 % 1-9km/s 0-9km/s# of Cyclones and Tornades / 10yr Days>25m/s each year 0 0 ? ?Annual precipitation(mm) 188 mm <10 mm <15mm <10mmAv summer humidity 25-50 % 30-50 % 10-25 % 30-50 % 25-30%Av winter humidity 10-30 % <10 % 5-15 % 10-15%Av snow depth 5 mm ? ?Maximum snow depth last 10yr

Electric power line Yes ? ?Water Yes No Yes ? ?Handy/Mobil service YesDistance to high band width internet 10km

Nearest hotels or lodge (mins) 15 40km 200km ESO or 200km 250km 220kmNearest restaurants (mins) 15 40km 200km ESO or 200km 250km 220kmNearest hospitals (mins) 15 200km,1500km ~200km, ~1500km ~200km, ~700km 250, 1500km 220, 1500km

Dangerous animals no No No No NoEndemic disease no No Chagas?Scientific facilities HESS CANGAROO ESO ESO No NoPolitical stubility Stable Stable Stable Stable

Sites - Parameters HESS Woomera Alma VLT La Silla El Huesco Site D

Sites - ParametersCTA-South


Known Cherenkov sitesKnown Cherenkov sites• Thomas Highlands, Namibia • Tenerife Teide, La Palma

• Himalaya Hanle (India)• Woomera (Australia)

Good quality possible sitesUseful for comparisons


Sites for optical astronomySites for optical astronomy

• Chilean sites– La Silla - Atacama desert– Paranal – 12 km from coast (VLT)– La Montura– …

High quality atmospheric conditions Between 2.000 and 3.000 m a.s.l. Caution: available area

La Silla


Archibarca

Catamarca

Chajnantor

1st half

Exploration of new sitesExploration of new sites

• Based on satellite surveyEramus Staden, 2001

– Cloud cover, water vapor– Data over 5 years

• 5-10 candidates in Northern Argentina

Good fraction of clear nights

Altitude above 3.500 m a.s.l.

Very large areaCan be isolated

clear

clear

nig

hts

nig

hts

ErasmusErasmus


Sus7052

Tolar G.Archibarca

Catamarca

Chajnantor

1st half

Antonio

Exploration of new sites (2)Exploration of new sites (2)• On site explorations (12-2006)

– E. Giraud, G. Vasileiadis, M. Gaczarzyk, T. Schweizer, A. Rovero, E. Colombo

– 4 sites visited

clear

clear

nig

hts

nig

hts

ErasmusErasmus

Pocitos

PocitosPOCITOS S 24° 32.118’ W 67° 4.363’

3722 m a.s.l.

N

• On site measurements− Telescope: Newton with CCD cam.− U, V, B

La Silla

Tolar Grande

Plateau below ALMA site

ALMA74%

67%

60%


ConclusionsConclusions

• Big activity of the WG members to identify candidates literacy, reports on web, personal contacts, visits,

measurements,…

• Draft of the WG has been submitted (23 pages)

• Good starting point for the Design StudyEven if Northern sites are so few and other possibilities have not yet investigated (e.g. South Utah)

• For the Design Study (Working Package 4):– Use long-term data from satellites and in-situ

measurements– Identify site facilities (for the access and the building phase)

Thank you to all Thank you to all for your contributionsfor your contributions

Report of the Working Group Calibration, Monitoring and Site Conveners: Conveners: M. Teshima, B....

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