HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF THE GRAVITATIONALLY LENSED CLOVERLEAF BROAD ABSORPTION-LINE QSO H1413- SPECTROSCOPY OF THE LY-ALPHA FOREST AND METAL-LINE SYSTEMS(1143 )

The intervening Ly alpha forest and metal-line absorbers toward the '' Cloverleaf'' gravitational lens H1413+1143 (z(em) = 2.54, m(v) approxi mate to 17) are examined along the four individual sight lines using H ST-FOS spectra. The observations probe the Ly alpha forest systems on size scales of up to 4 h(-1) kpc(H-o = 100 h km s(-1) Mpc(-1), q(o) = 0.5) and metal-line systems on scales up to 6 h(-1) kpc. The equivalen t widths of Ly alpha forest lines in general are well correlated along the four different lines of sight and are consistent with the sight l ines piercing the same absorbers. The heavy-element systems clearly sh ow evidence for differences. One striking difference is seen in a syst em at z(abs) = 2.0969 in which the Ly alpha line possesses a column de nsity approaching log N(H I) = 19.7 in component B but not exceeding l og N(H I) = 18.4 in any of the other three components. Simulations sho w that a circular absorber responsible for such a scenario has a radiu s of less than or equal to 10 h(-1) kpc with a 90% confidence level, a ssuming a lens redshift of z(lens) = 1.55. The z(abs) = 1.6595 system contains a probable damped Ly alpha line and shows evidence for rotati on. A system at z(abs) = 1.4377 exhibits very significant Fe II absorp tion in only two of the components at the level of sensitivity of the observations. Examination of how the absorption-line equivalent widths are correlated between the component spectra can provide information about whether all four lines of sight to the QSO are passing through t he same absorbers, placing limits on absorber sizes and shapes. The fo ur sight lines toward H1413+1143 provide a unique geometry for this ty pe of study.