The Wide Field Optical Spectrometer (WFOS) is being developed as a first light instrument capability. The aim is to provide near-ultraviolet and optical (0.3 – 1.0 μm wavelength) spectroscopy (R~3500-5000) over a more than 40 square arcminute field-of-view of hundreds of objects simultaneously. Broad band imaging and observations of single objects are also planned modes. WFOS will be designed to operate in either seeing limited conditions or with a Ground Layer Adaptive Optics system.
The concept for a slit mask based system was originally conceived in 2006. However in 2016, when the next design phase was proceeding, prohibitive technical challenges were identified in the design. Different options were considered and two were produced; a slit-mask based imaging spectrometer with field of view ~25 square arcminutes, R~1500-15,000 and multiplexing of ~50 and a fiber based spectrometer with a 50 square arcminute field of view, R=3500, multiplexing of >125 target/sky fiber pairs and 1 to 2 square arcminute imager. Each design has different strengths and limitations.
Present status (September 2018): A broad evaluation of the scientific priorities for the TMT science community has taken place in which many science cases were considered and broad community input was sought. In parallel an extensive technical and cost evaluation for both designs was undertaken that involved groups across the TMT partnership. Design options, upgrade paths, technical risks and other aspects are all being considered. A downselect to one concept is planned for later in 2018.
IRIS is a first generation near-infrared (0.84-2.4 μm) instrument being designed to sample the diffraction limit of the Thirty Meter Telescope (TMT). IRIS will include an integral field spectrograph (IFS) with R>4000 and imaging camera (34"x34"). Both the IFS and imager will take advantage of the high spatial resolution achieved with the Narrow-Field Infrared Adaptive Optics System (NFIRAOS). The IFS will provide four spatial scales (0.004", 0.009", 0.025", 0.05"). IRIS will achieve an angular resolution ten times better than images from the Hubble Space Telescope, and will be the highest angular resolution near-infrared instrument in the world.
The first light Adaptive Optics (AO) architecture for the TMT has been defined to provide near-diffraction-limited wavefront quality and high sky coverage in the near infra-red (IR) for the first TMT science instruments IRIS and IRMS. Design, fabrication and prototyping activities of the TMT first light AO systems and their components in Canada, China, France, and in the US are currently on schedule.
The entire TMT observatory has been designed to support a wide range of different forms of facility class instrumentation. To do this, a suite of instrument concepts was developed and the observatory design was developed around them. These longstanding ideas for instruments have continued to evolve. Several instrument concepts are being actively developed and are evolving beyond the original ideas. Several new ideas have also arisen and may be developed further. The prioritization of needed instrument capabilities and the resulting strategy or sequence for instrument development is based on community explorations.