  We report dense lightcurve photometry, $BVR_{c}$ colors and phase - mag curve
of (6478) Gault, an active asteroid with sporadic comet-like ejection of dust.
We collected optical observations along the 2020 Jul-Nov months during which
the asteroid appear always star-like, without any form of perceptible activity.
We found complex lightcurves, with low amplitude around opposition and a bit
higher amplitude far opposition, with a mean best rotation period of $2.46_{\pm
0.02}$ h. Shape changes were observed in the phased lightcurves after
opposition, a probable indication of concavities and surface irregularities. We
suspect the existence of an Amplitude-Phase Relationship in $C$ band. The mean
colors are $B-V = +0.84_{\pm 0.04}$, $V-R_{c} = +0.43_{\pm 0.03}$ and $B-R_{c}
= +1.27_{\pm 0.02}$, compatible with an S-type asteroid, but variables with the
rotational phase index of a non-homogeneous surface composition. From our phase
- mag curve and Shevchenko's empirical photometric system, the geometric albedo
result $p_V=0.13_{\pm 0.04}$, lower than the average value of the S-class. We
estimate an absolute mag in $V$ band of about +14.9 and this, together with the
albedo value, allows to estimate a diameter of about 3-4 km, so Gault may be
smaller than previously thought.
