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We measured the photoabsorption cross sections of the S-R continuum at 78 K and 295 K in the wavelength region 130-175 nm. The I-m Seya-Namioka vacuum spectrometer on the BL-12A beam line at the Photon Factory, KEK, Japan was used, in the first order, with synchrotron radiation as a background continuum. The measurements have been performed on a relative scale in scanning mode and also on the absolute scale at every 5 nm interval. These absolute cross sections measurements of $O2$ have been used to put the relative cross sections on a firm absolute basis throughout the region 130-175 nm. Temperature effects on the cross sections of the S-R continuum are clearly seen and cross sections at 78 K are about 80% of those at 295 K. At 78 K only the $\nu \prime \prime =0$ level is populated significantly. The calculated cross sections do not reproduce quantitatively the experimental temperature effects. This work is supported by NASA grant NAG5-484 to Smithsonian Astrophysical Observatory and by NSF grant ATM-90-19188 to Harvard College Observatory.