  The radio millisecond pulsar J1713+0747 is regarded as one of the
highest-precision clocks in the sky, and is regularly timed for the purpose of
detecting gravitational waves. The International Pulsar Timing Array
collaboration undertook a 24-hour global observation of PSR J1713+0747 in an
effort to better quantify sources of timing noise in this pulsar, particularly
on intermediate (1 - 24 hr) timescales. We observed the pulsar continuously
over 24 hr with the Arecibo, Effelsberg, GMRT, Green Bank, LOFAR, Lovell,
Nancay, Parkes, and WSRT radio telescopes. The combined pulse times-of-arrival
presented here provide an estimate of what sources of timing noise, excluding
DM variations, would be present as compared to an idealized root-N improvement
in timing precision, where N is the number of pulses analyzed. In the case of
this particular pulsar, we find that intrinsic pulse phase jitter dominates
arrival time precision when the S/N of single pulses exceeds unity, as measured
using the eight telescopes that observed at L-band/1.4 GHz. We present first
results of specific phenomena probed on the unusually long timescale (for a
single continuous observing session) of tens of hours, in particular
interstellar scintillation, and discuss the degree to which scintillation and
profile evolution affect precision timing. This paper presents the data set as
a basis for future, deeper studies.
