This is the only period that achieves internal consistency
for the group of observations during the 16-day interval Dec 28 - Jan 13
assuming retrograde rotation (which affords a slightly better fit than prograde,
shown in the next figure). The data have been folded according to P = 99.36
hrs. All mag's adjusted to 2008.12.29. All times have been shifted to
equivalent view toward ecliptic longitude zero. The "model fit" is a 4-term
sinusoid (with periods = P, P/2, P/3 & P/4 and adjustable phases). The
average magnitude is r' = 17.16, and since H(V-band) = 14.6 the measured
averaage r'-band magnitude corresponds
to H(r'-band) = 14.39.
The above "folded" RLC is only valid if the RLC shape
is the same throughout the 17-day interval on which observations were
made and the assumed dependence of brightness on phase angle (used by the
JPL asteroid ephemeris generator, Horizons - web interface: http://ssd.jpl.nasa.gov/horizons.cgi#top
RLC shape can be affected by the viewing geometry (i.e., orientation of rotation
axis with respect to the viewing direction) as well as the sun-asteroid-Earth
angle. During the above interval the viewing geometry didn't change much
(i.e., ecliptic longitude ranges from +37.5 to +38.6), and the sun-asteroid-Earth
angle was also restricted to a small rage (i.e., from +27.7 to +32.7 degrees).
It is therefore probably reasonable to assume that the RLC shape remained
constant during the 17-day interval.
Prograde version, with higher reduced chi-square.
As this graph shows the prograde solution is almost as good as
the retrograde one. The reduced chi-squared is 5.46 versus 4.75 for retrograde.
Individual Observing Session RLCs
Wind cut short this observing session.
At ~ 4.3 UT the NEO passed close to a bright
star that corrupted the sky background annulus. At ~ 5.2 UT a background
star went through the signal aperture.
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