  The NASA Double Asteroid Redirection Test (DART) spacecraft successfully
impacted the Didymos-Dimorphos binary asteroid system on 2022 September 26 UTC.
We provide an update to its pre-impact mutual orbit and estimate the
post-impact physical and orbital parameters, derived using ground-based
photometric observations taken from July 2022 to February 2023. We found that
the total change of the orbital period was $-33.240 \pm 0.072$ min. (all
uncertainties are 3$\sigma$). We obtained the eccentricity of the post-impact
orbit to be $0.028 \pm 0.016$ and the apsidal precession rate of $7.3 \pm 2.0$
deg./day from the impact to 2022 December 2. The data taken later in December
to February suggest that the eccentricity dropped close to zero or the orbit
became chaotic approximately 70 days after the impact. Most of the period
change took place immediately after the impact but in a few weeks following the
impact it was followed by additional change of $-27^{+19}_{-58}$ seconds or
$-19 \pm 18$ seconds (the two values depend on the approach we used to describe
the evolution of the orbital period after the impact -- an exponentially
decreasing angular acceleration or an assumption of a constant orbital period,
which changed abruptly some time after the impact, respectively). We estimate
the pre-impact Dimorphos-Didymos size ratio was $0.223 \pm 0.012$ and the
post-impact is $0.202 \pm 0.018$, which indicates a marginally significant
reduction of Dimorphos' volume by ($9 \pm 9) \%$ as the result of the impact.
