ToO Observations of Galactic Gamma-ray Transients Discovered with Fermi

The Fermi, AGILE, and EGRET gammaray telescopes have discovered more than adozen transient sources of GeV gamma rays near the Galactic plane. Only six ofthese sources have been identified at other wavelengths, four as novae, a newclass of GeV gammaray sources. The physical nature of the other Galacticgammaray transients is still unknown. These GeV transients may potentiallyrepresent a new class of gammaray emitting objects. We propose XMMNewton ToOobservations of new transients discovered with the Fermi LAT in the Galacticplane. The XMMNewton observations will enable us to more accurately localizethe transients, identify counterparts at other wavelengths, determine theirXray flux and spectrum, and characterize their variability. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]