  We present an analysis of the Ly-a forest toward 3C 273 from the Space
Telescope Imaging Spectrograph at ~7 km/s resolution, along with re-processed
data from the Far Ultraviolet Spectroscopic Explorer. The high UV flux of 3C
273 allows us to probe the weak, low z absorbers. The main sample consists of
21 HI absorbers that we could discriminate to a sensitivity of log NHI~ 12.5.
The redshift density for absorbers with 13.1<log NHI<14.0 is ~1.5 sigma below
the mean for other lines of sight; for log NHI >= 12.5, it is consistent with
numerical model predictions. The Doppler parameter distribution is consistent
with other low z samples. We find no evidence for a break in the column density
power-law distribution to log NHI=12.3. A broad Ly-a absorber (BLA) is within
Delta v =< 50 km/s and 1.3 local frame Mpc of two ~0.5L* galaxies, with an OVI
absorber ~700 km/s away, similarly close to three galaxies and indicating
overdense environments. We detect clustering on the Delta v<1000 km/s scale at
3.4 sigma significance for log NHI >= 12.6, consistent with the level predicted
from hydrodynamical simulations, and indication for a Ly-a forest void at
0.09<z<0.12. We find at least two components for the z=0.0053 Virgo absorber,
but the total NHI column is not significantly changed.
