THEMIS/GBO Engineering Peer Review 1 UCB, Oct. 17, 2003 Ground Based Observatories (GBO) All Sky Imager Design Stewart Harris - UCB

THEMIS/GBO Engineering Peer Review 2 UCB, Oct. 17, 2003 All Sky Imager Overview Will use same design validated with Prototype Add Environmental Enclosure –Available for use where needed –Requires heating / temperature control –Provides flexible mounting interface Add Sun Shield Add USB extender capability

THEMIS/GBO Engineering Peer Review 3 UCB, Oct. 17, 2003 All Sky Imager w/ USB I/F Starlight Xpress MX716

THEMIS/GBO Engineering Peer Review 4 UCB, Oct. 17, 2003 ASI Enclosure Requirements: House Imager/Lens and USB Interface and USB Extender Operate in external ambient temperatures -50º to +40ºC Vertically mounted Internal clamp for camera and to stiffen lens Maintain internal temperature at 20º± 10ºC Sealed unit w/ nitrogen purge –Dessicant used for field repairs Designed to mount on flat base, or on pipe (1.5” – 2”) – Manual levelling Polycarbonate / acrylic dome –Cover provided for protection in shipping/inactive periods –Cover can be used for collecting Dark Images Electrical connector(s) – pressure sealed

THEMIS/GBO Engineering Peer Review 5 UCB, Oct. 17, 2003 ASI Enclosure Concept External Construction Internal Construction Pipe Clamp Shown Design concept: Allison Park Group, Inc.

THEMIS/GBO Engineering Peer Review 6 UCB, Oct. 17, 2003 ASI Sun Shield Background ASI must survive, without degradation, non-operating exposure to daytime sun exposure CCD is Sony Interline Transfer device ICX249AL –Features “microlens” on each pixel, an organic material subject to deterioration due to UV exposure All Sky Lens uses Peleng Fisheye f/3.5 –A/R coating exhibited discoloration after one summer in Athabasca Result Need internal sun shield Drives housing diameter and heat required

THEMIS/GBO Engineering Peer Review 7 UCB, Oct. 17, 2003 Sun Shield Concept Retracted (Fail-safe) Position Closed Position Rotary Solenoid All Sky Lens

THEMIS/GBO Engineering Peer Review 8 UCB, Oct. 17, 2003 ASI Enclosure Heating Assumptions: T AMBIENT = -50º C T INTERNAL = +10º C Dome OD grows as barrel OD increases to keep “ledge” small Stainless steel shell, “thinsulate” insulation Internal heat dissipation from electronics negligible

THEMIS/GBO Engineering Peer Review 9 UCB, Oct. 17, 2003 USB Extender Status: Demonstrated 25’ Features: Extends USB signalling distance –Mitigates 5m cable length limitation Uses standard CAT5 cable (4-pair) Small, enclosed in ASI enclosure

THEMIS/GBO Engineering Peer Review 10 UCB, Oct. 17, 2003 ASI Electrical Interface Electrical: Two connectors: Data and Power Physical: Hermetically sealed, O-ring closure on housing Stainless steel shell Weatherproof