2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/226506Constraints on the core temperature of the Sun and on neutrino-oscillation parameters are obtained by comparing the combined Homestake, Kamiokande, SAGE and GALLEX solar neutrino data with Standard Solar Models (SSM) and with non-standard solar models parameterized by a phenomenological central temperature ($T_c$). If the Sun is 2\% cooler or 3\% warmer than predicted by SSMs, the MSW parameters we determine are consistent with different grand unified theories.(2 pages), UPR-531-T, Latex, 4 figures upon request. Revised version replacing hep-ph/9212241 which was missing macro esprc2.texHigh Energy Physics - Phenomenologytext