  Kuiper Belt Objects (KBOs) are generally very faint and cannot in practice be
monitored with a well-sampled long-term light curve; so our discovery of the
bright KBO 2000 EB173 offers an excellent opportunity for synoptic studies. We
present a well-sampled photometric time series (77 R magnitudes and 29 V
magnitudes on 78 nights) over a 225-day time span centered on the 2001
opposition. The light curve (corrected to the year 2001 opposition distance)
varies from 19.11 to 19.39 mag with a single peak that is smooth, time
symmetric, and coincident with opposition. All variations in the light curve
are consistent with a linear opposition surge (Ropp = 19.083 + 0.125Xalpha,
where alpha is the solar phase angle), while any rotational modulation must
have a peak-to-peak amplitude of less than 0.097 mag. This is the first
measured opposition surge for any KBO (other than Pluto). The V-R color is
0.63+-0.02, with no apparent variation with phase at the few percent level.
With R=19.11 at opposition, 2000 EB173 remains the brightest known KBO and a
prime target for future photometric and spectroscopic studies.
