  We observed Episodically Active Asteroid (6478) Gault in 2020 with multiple
telescopes in Asia and North America and have found that it is no longer active
after its recent outbursts at the end of 2018 and start of 2019. The inactivity
during this apparation allowed us to measure the absolute magnitude of Gault of
H_r = 14.63 +/- 0.02, G_r = 0.21 +/- 0.02 from our secular phasecurve
observations. In addition, we were able to constrain Gault's rotation period
using time-series photometric lightcurves taken over 17 hours on multiple days
in 2020 August, September and October. The photometric lightcurves have a
repeating $\lesssim$0.05 magnitude feature suggesting that (6478) Gault has a
rotation period of ~2.5 hours and may have a semi-spherical or top-like shape,
much like Near-Earth Asteroids Ryugu and Bennu. The rotation period of ~2.5
hours is near to the expected critical rotation period for an asteroid with the
physical properties of (6478) Gault suggesting that its activity observed over
multiple epochs is due to surface mass shedding from its fast rotation spun up
by the Yarkovsky-O'Keefe-Radzievskii-Paddack effect.
