We present two-colour CCD imaging of 2060 Chiron obtained between 1996 and 1998 with the 2.15 m telescope at CASLEO ( San Juan , Argentina ) .
These post-perihelion observations show that Chiron was then near its historical brightness minima , however a coma was clearly detected .
The dynamical state of the coma is studied by means of azimuthally averaged surface brightness profiles , which show the signatures of radiation pressure on the dust grain distribution .
Aperture photometry shows an achromatic dimming with an amplitude \approx 0.09 mag in approximately one hour .
If due to rotation of the nucleus , this rather high amplitude is used to derive a new value for the nuclear magnitude , m _ { 0 } \approx 6.80 mag .