Spectral type and geometric albedo of (98943) 2001 CC21, the Hayabusa2# mission target

We conducted optical polarimetry and near-infrared spectroscopy of Japan Aerospace Exploration Agency (JAXA)’s Hayabusa2# mission target, (98943) 2001 CC21, in early 2023. Our new observations indicate that this asteroid has a polarimetric inversion angle of ∼20°, absorption bands around 0.9 and 1.9 μm, and a geometric albedo of 0.23 ± 0.04. All these features are consistent with those of S types but inconsistent with L types. Based on this evidence, we conclude that JAXA’s Hayabusa2# spacecraft will explore an S-type asteroid (more specifically, an L or LL chondrite-like object) with albedo and size (0.44–0.53 km when we assume the absolute magnitude of 18.8) similar to (25143) Itokawa.