Timing of our Ryugu observations using the Gemini-South telescope. (a) Apparent visual magnitude (AP-mag) of asteroid Ryugu provided by HORIZONS (https://ssd.jpl.nasa.gov/horizons.cgi). Our visible spectra were observed during the last observation opportunity (summer of 2012) before the launch of Hayabusa2 in December 2014. (b) Comparison of the rotational phases among our three observations. The black lines indicate the length of observations for these three nights. The blue lines indicate rotational phases that would have been observed at the respective observation times.