A new study on Japanese Geodetic Satellite Ajisai, led by Dr D Kucharski, has just been published online. Using a photometry observation system in Graz, Austria, the reflectivity of Ajisai surface could be very precisely monitored.
Otsubo is one of the coauthors.

Authors: D. Kucharski, G. Kirchner, T. Otsubo, H. Kunimori, M. K. Jah, F. Koidl, J. C. Bennett, H-C Lim, P. Wang, M. Steindorfer, K. Sośnica
Title: Hypertemporal photometric measurement of spaceborne mirrors specular reflectivity for Laser Time Transfer link model
Journal: Advances in Space Research (Available online 28 May 2019)

https://doi.org/10.1016/j.asr.2019.05.030