We present a description and briefly introduce the dataset of the SOHO Joint observation Program JOP 099. JOP 099 involved SOHO instruments CDS, MDI, EIT and LASCO, together with TRACE, and two new ground-based instruments: HASTA (H-Alpha Solar Telescope for Argentina) and MICA (Mirror Coronagraph for Argentina). The main objective of this program was to study the physical structure and magnetic evolution of filaments, trying to understand the conditions that lead to the eruption of a prominence, often associated with a CME. JOP 099 was running for the first time in April, 1999. The program was the first official campaign for the new instruments in Argentina. In this preliminary report we illustrate how the JOP data (especially the TRACE data) can be used to constrain our magnetic field extrapolations.