  We calculate electromagnetic production from highly excited hadronic matter
created in heavy ion collisions. The rates include the usual lowest order
processes in quark-gluon plasma plus the usual reactions in the hadronic phase,
related with rho,a_1 mesons. The space-time integration is done using a
hydrodynamical model. We have found that dilepton mass spectrum agrees with
results of other previous works, but *disagrees* with the CERES dilepton data.
In order to explain these data, some "unconventional" production mechanism need
to be incorporated: we discuss especially the notion of modified rho,a_1
masses, which indeed may explain the data. Other suggestions (e.g. the
longer-lived fireball) to increase the production of low mass dileptons seem to
be insufficient for the task. The results for direct photon production are
below the current WA80 experimental bounds, for all variants considered.
