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Ian Skillen
OSCA Instrument Specialist


Note that as part of ongoing rationalisation of the WHT's instrument suite, and following consultation with the ING's observing communities, the adaptive-optics instruments (NAOMI/INGRID, NAOMI/OASIS) are not available after 31st January 2015, i.e. from 2015A, and that OSCA is not available in 2014B either.

OSCA image of 
a star behind the 2 arcsec mask
The Optimised Stellar Coronograph for Adaptive Optics (OSCA) is a coronograph that is an integral part of the NAOMI adaptve optics system, and can be used together with the infrared camera, INGRID. It was installed and commissioned in 2002 and has been offered to the community since semester 2003A.

OSCA was built at the Optical Science Laboratory of the University College London (UCL) by Peter Doel (PI). Click here to go to the UCL webpage for OSCA

OSCA effectively suppresses the light from a bright object and therefore enables the detection of faint structures or objects close it which would otherwise be hidden in its glare. OSCA's field of view has diameter 27 arcsec.

OSCA is mounted permanently after the AO system NAOMI and can be deployed into the beam within a few seconds, making the system very flexible during nighttime. Nevertheless potential observers are asked to inform ING staff well before their run if they are going to use OSCA as it requires some preparation of the AO system for it to be fully optimized for the use of the coronograph.

Currently six different mask sizes with hard edges are permanently mounted inside OSCA: 0"2, 0"65, 0"8, 1"0, 1"6 and 2"0. Two gaussian shaped masks with fwhm=0"5 and 0"6, optimized for the optical wavelength domain, are also available. All masks can be selected remotely.

OSCA can only be used in combination with INGRID for near infrared (J, H, Ks or narrow bands) imaging observations. There is no possibility of using OSCA with OASIS.

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Contact:  (OSCA Instrument Specialist)
Last modified: 07 August 2014