  The Apollo-type near-Earth asteroid (155140) 2005 UD is thought to be a
member of the Phaethon-Geminid meteor stream Complex (PGC). Its basic physical
parameters are important for unveiling its origin and its relationship to the
other PGC members as well as to the Geminid stream. Adopting the
Lommel-Seeliger ellipsoid method and $H,G_1,G_2$ phase function, we carry out
spin, shape, and phase curve inversion using the photometric data of 2005~UD.
The data consists of 11 new lightcurves, 3 lightcurves downloaded from the
Minor Planet Center, and 166 sparse data points downloaded from the Zwicky
Transient Facility database. As a result, we derive the pole solution of
($285^\circ.8^{+1.1}_{-5.3}$, $ -25^\circ.8^{+5.3}_{-12.5}$) in the ecliptic
frame of J2000.0 with the rotational period of $5.2340$ h. The corresponding
triaxial shape (semiaxes $a>b>c$) is estimated as $b/a= 0.76^{+0.01}_{-0.01}$
and $c/a=0.40^{+0.03}_{-0.01}$. Using the calibrated photometric data of 2005
UD, the $H,G_1,G_2$ parameters are estimated as $17.19^{+0.10}_{-0.09}$ mag,
$0.573^{+0.088}_{-0.069}$, and $0.004^{+0.020}_{-0.021}$, respectively.
Correspondingly, the phase integral $q$, photometric phase coefficient $k$, and
the enhancement factor $\zeta$ are 0.2447, -1.9011, and 0.7344. From the values
of $G_1$ and $G_2$, 2005 UD is likely to be a C-type asteroid. We estimate the
equivalent diameter of 2005 UD from the new $H$-value: it is 1.30 km using the
new geometric albedo of 0.14.
