We present a novel concept for a highly sensitive, medium spectral resolution optical through near-IR spectrograph.
KIDSpec, the Kinetic Inductance Detector Spectrograph, uses the intrinsic energy resolving capability of an array of
optical/IR-sensitive MKIDs to distinguish multiple orders from a low line-density (echelle) grating. MKID arrays have a
wide bandpass (0.1-2.5um) and good quantum efficiency, making them strong candidates for replacing CCDs in many
astronomical instruments. By acting as an ‘order resolver’, the MKID array replaces the cross-disperser in an echelle
spectrograph. This greatly simplifies the optical layout of the spectrograph and enables longer slits than are possible with
cross-dispersed instruments. KIDSpec would have similar capabilities to ESO’s X-shooter instrument. It would provide
an R=4000-10,000 spectrum covering the entire optical and near-IR spectral range. In addition to a ‘long-slit’ mode, the
IFU would provide a small (~50 spaxel) field-of-view for spatially resolved sources. In addition, the photon-counting
operation of MKIDs and their photon-energy resolving ability enable a read-noise free spectrum with perfect cosmic ray
removal. The spectral resolution would be sufficient to remove the bright night-sky lines without the additional pixel
noise, making the instrument more sensitive than an equivalent semiconductor-based instrument.
KIDSpec would enhance many existing high-profile science cases, including transient (GRB, SNe, etc.) follow-up,
redshift determination of faint objects and transit spectroscopy of exoplanets. In addition it will enable unique science
cases, such as dynamical mass estimates of the compact objects in ultra-compact binaries.