Presentation #143.02 in the session Dust — iPoster Session.
Spectroscopic measurements of Milky Way interstellar dust extinction curves are often limited to UV and/or optical wavelength ranges. However, the near-infrared region also harbors interesting information about the properties of interstellar dust grains, such as their size distributions and composition. Nevertheless, measurements in the near-infrared are usually based on only a handful of broadband data points. In our recent study (Decleir et al., 2022, revised version submitted to ApJ), we extended the extinction curve measurements to 5 micron, using new, high signal-to-noise spectra from the IRTF/SpeX instrument for a sample of sightlines in the Milky Way. In this poster, I will present our most interesting findings, including a measurement of the average diffuse Milky Way near-infrared extinction curve, correlations between extinction parameters, the dependence of variations in the extinction on a single parameter, R(V), and the detection of water ice in some of the sightlines. I will also highlight how recent HST observations, combined with planned JWST observations will advance our understanding of interstellar dust properties in the Milky Way.