Highly Multiplexed Spectroscopy at IR Wavelengths: From Instrument Design to Pipelines

There has been a significant drive towards developing highly multiplexed spectrographs to effectively utilise the capabilities of larger aperture size telescopes in optical and IR wavelengths. Two main classes of instruments that use a high multiplexing approach are Multi-Object Spectrographs (MOS) and Integral Field Units (IFU). Multi-Object spectrographs that use multiple slit/fiber mechanisms have been one of the common instruments built on moderate to large aperture telescopes. I will discuss the continuation of the instrument development of MOIS, a Multi-Object Infrared Spectrograph designed for Devasthal Optical Telescope.  We have completed the reoptimization of the optical design to 120K, stray light analysis and  tolerance analysis during this phase. We have also developed the raw data simulator for MOIS that has been used to especially characterise the effect of thermal noise from the slit unit on the data and give realistic exposure time calculations.  Additionally I will discuss lenslet-based IFU spectroscopy which is one of the techniques that is used in a large number of current and proposed instruments for ground-based and space-based telescopes. Lenslet-based IFUs provide a high spatial sampling for obtaining 3D spectral cubes of a target field. With a large number of closely spaced spectra on the detector, unique instrument modelling and data reduction techniques must be implemented to retrieve spectral data from lenslet-based IFUs.  I have been  developing data reduction techniques for such lenslet IFU that use instrument models in the extraction process to obtain optimal data reduction. I will discuss some of these techniques that are used in the context of  TMT-IRIS, Keck-SCALES, and Keck-LIGER instruments.