  Infrared spectroscopy with medium to high spectral resolution is essential to
characterize the gas content of circumstellar disks. Unfortunately, conducting
continuum and line radiative transfer of thermochemical disk models is too
time-consuming to carry out large parameter studies. Simpler approaches using a
slab model to fit continuum-subtracted spectra require the identification of
either the global or local continuum. Continuum subtraction, particularly when
covering a broad wavelength range, is challenging but critical in rich
molecular spectra as hot (several hundreds K) molecular emission lines can also
produce a pseudo continuum. In this work, we present CLIcK, a flexible tool to
simultaneously fit the continuum and line emission. The DDN01 continuum model
(Dullemond et al. 2001) and a plane-parallel slab of gas in local thermodynamic
equilibrium are adopted to simulate the continuum and line emission
respectively, both of them are fast enough for homogeneous studies of large
disk samples. We applied CLIcK to fit the observed water spectrum of the AA Tau
disk and obtained water vapor properties that are consistent with literature
results. We also demonstrate that CLIcK properly retrieves the input parameters
used to simulate the water spectrum of a circumstellar disk. CLIcK will be a
versatile tool for the interpretation of future James Webb Space Telescope
spectra.
