Interstellar H2 toward HD 147888
  The ultraviolet and far--ultraviolet spectra of HD 147888 allows to access the v=0 as well as higher vibrational levels of the ground H2 electronic level. We have determined column densities of the H2 molecule on vibrational levels v=0-5 and rotational levels J=0-6.   The ortho to para H2 ratio for the excited vibrational states equals to 1.2. For the lowest vibrational state v=0 and rotational level J=1 the ortho to para H2 ratio is only 0.16. The temperature of ortho-para thermodynamical equilibrium is T_OP=43+-3 K.   The large number of H2 absorption lines in the HST spectra allows to determine column densities even from a noisy spectra.   The measurements of H2 column densities on excited vibrational levels (from the HST spectra) leads to constrains of radiation field in photon-dominated regions (PDR) models of interstellar cloud towards HD 147888. 
Piotr Gnacinski
astro-ph.GA