Using high-resolution ultraviolet spectra of 16 low-z QSOs obtained with the E140M echelle mode of the Space Telescope Imaging Spectrograph, we study the physical conditions and statistics of OVI absorption in the intergalactic medium (IGM) at z<0.5. We identify 51 intervening (z_abs_30m{AA}, the number of OVI absorbers per unit redshift dN/dz=15.6^+2.9^-2.4(21.0^+3.2^-2.8), and this decreases to dN/dz=0.9^+1.0^-0.5(0.3^+0.7^-0.3) for W_r_>300m{AA}. The number per redshift increases steeply as z_abs_ approaches z_QSO_; we find that dN/dz is ~3-10 times higher within 2500km/s of z_QSO_. The most striking difference between intervening and proximate systems is that some proximate absorbers have substantially lower HI/OVI ratios.
Cone search capability for table J/ApJS/177/39/list (QSO's list)
