Atmospheric Visibility Monitoring (AVM') Program - DESCANSO

Atmospheric Visibility Monitoring (AVM’) Program

Muthu Jeganathan and Loretta Tong

JPL

Jet Propulsion Laboratory

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TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

JPL

Outline

w Program objective w Project overview and description @h) a)

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w Atmospheric transmission data w Future upgrades & enhancements w Summary

TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

JPL

w Obtain Atmospheric Transmission Statistics Data to Support Optical Communications +Atnmspherie loss in optical comm. channel +Joint PDFs for multiple site reception +Statistical modeling +Extrapolate PDI?s for other sites

TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

AVM: Description H An autonomous system that measures ground intensity of stars through different filters 10-inch (4-cm) diameter f/10 telescope Six spectral filters (5 operational) +

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Cooled slow-scan CCD camera Weather station to guard system 386 powered PC controls all subsystems and collects data

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TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

AVM: Description

JPL

M One star observed every 15 minutes + Standard stars between O & 4 magnitude About 50 stars in list covering entire sky w Each star observed through 6 filters +

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+ Narrow band: 532 nm, 830 nm & L8 + Broad band: Astronomical V, R & I * 24 observations (images) per hour

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TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

I JPL

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AVM: Description

Collected data is automatically sent via modem to a dedicated computer at JPL on a daily basis Image/data processing reveals star intensity values on ground Attenuation determined by normalizing ground intensity values to above-theatmosphere intensity values Subsequent data analysis provides statistical information of interest

TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

JPL

AVM: Sites Ii

Table Mountain Facility (TMF) + Altitude: 2.3 km (7500 ft) m Mt. Lemmon near Tucson Arizona + Altitude: 2.8 km (9150 ft) u uI* m w Goldstone (as of August 1996)

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+ Altitude: 1 km (3400 ft)

TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

JPL

System Calibration

* Calibration achieved from observation of stars through different air-mass

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Y=yo–qx

TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

Calibration

JPL

Observation of star #5933 through 860 nm filter from TMF 7.4 !

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TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE

Visibility Statistics

JPL

Site: Mt. Lemmon; Filter 860 nm Period: 3rd and 4th quarter of 1995 -1.0 0.9

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~2738 observations 7/1/95 - 9/30/95

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“ . . . . . . . . . . . . . . . ~+– 4778 obsewations 10/1/95 - 12/31/95 ~~

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2 4 6 8 10 12 14 16’ Zenith attenuation -- aO (dB)

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