We present visible and near-infrared observations of a near-Earth object ( NEO ) , 2012 \mathrm { TC _ { 4 } } .
The NEO 2012 \mathrm { TC _ { 4 } } approached close to the Earth at a distance of about 50,000 km in October 2017 .
This close approach provided a practical exercise for planetary defense .
This apparition was also an appropriate opportunity to investigate 2012 \mathrm { TC _ { 4 } } , which is a monolithic asteroid \citep Polishook13 .
We conducted the observation campaign of 2012 \mathrm { TC _ { 4 } } using six small- and medium-sized telescopes .
The multiband photometry analysis showed that the taxonomic class of 2012 \mathrm { TC _ { 4 } } to be an X-type .
In particular , we successfully obtained the high time resolution lightcurve of 2012 \mathrm { TC _ { 4 } } with the Tomo-e Gozen camera , which is the world ’ s first wide-field CMOS camera , mounted on the 1.05 m Schmidt telescope at Kiso Observatory .
The shape and rotational motion models of 2012 \mathrm { TC _ { 4 } } were derived from the lightcurve .
When 2012 \mathrm { TC _ { 4 } } was assumed to be a triaxial ellipsoid , the rotational and precession periods were 8.47 \pm 0.01 min and 12.25 \pm 0.01 min , respectively , with the long axis mode .
This indicates that 2012 \mathrm { TC _ { 4 } } is a tumbling and monolithic asteroid .
The shape models showed that the plausible axial lengths to be 6.2 \times 8.0 \times 14.9 m or 3.3 \times 8.0 \times 14.3 m. The flattened and elongated shape indicates that 2012 \mathrm { TC _ { 4 } } is a fragment produced by a impact event .
We also estimated the excitation timescale , which implied that the impact event happened within \sim 3 \times 10 ^ { 5 } yr and 2012 \mathrm { TC _ { 4 } } has a fresh surface .