  The radio source G1.9+0.3 has recently been identified as the youngest known
Galactic supernova remnant, with a putative age of ~100 years. We present a
radio light curve for G1.9+0.3 based on 25 epochs of observation with the
Molonglo Observatory Synthesis Telescope, spanning 20 years from 1988 to 2007.
These observations are all at the same frequency (843 MHz) and comparable
resolutions (43" x 91" or 43" x 95") and cover one fifth of the estimated
lifetime of the supernova remnant. We find that the flux density has increased
at a rate of 1.22 +0.24/-0.16 per cent per year over the last two decades,
suggesting that G1.9+0.3 is undergoing a period of magnetic field
amplification.
