The optical integral-field spectrograph OASIS is installed at one of the science ports of NAOMI,
in the William Herschel Telescope's
Adaptive Optics-dedicated Nasmyth enclosure.
The instrument is optimised for use with adaptive optics, but may also
be used without it.
Light from the sky is imaged onto OASIS's
IFU, which contains ~1100 hexagonal lenslets in a rectangular array.
Three different enlargers can currently be placed in front of the
lenslet array in order to change the field of view and corresponding
spatial sampling per lenslet.
The light from each lenslet is then dispersed using a
grism (or prism) and imaged onto the 2k
x 4k detector. 15 different spectroscopic configurations are
available, giving a variety of spectral ranges and resolutions. The
~1100 spectra can then be extracted using a dedicated data reduction package to form a datacube.
As the spatial sampling and the spectroscopic
configuration are independent of each other, this leads to a total of
45 possible configurations for spectroscopy. The available options are
given on the OASIS Configurations
Information about applying for time, using adaptive
optics with OASIS, data reduction and other technical details can be
found on the FAQs page. Please note that
all OASIS observations are performed in service mode by ING staff