We report the discovery of Type I ( thermonuclear ) X-ray bursts from the transient source XMMU J181227.8–181234 = XTE J1812–182 .
We found 7 X-ray bursts in Rossi X-ray Timing Explorer observations during the 2008 outburst , confirming the source as a neutron star low mass X-ray binary .
Based on the measured burst fluence and the average recurrence time of 1.4 ^ { +0.9 } _ { -0.5 } hr , we deduce that the source is accreting almost pure helium ( X \leq 0.1 ) fuel .
Two bursts occurred just 18 minutes apart ; the first short waiting time bursts observed in a source accreting hydrogen-poor fuel .
Taking into consideration the effects on the burst and persistent flux due to the inferred system inclination of 30 \pm { 10 } \textdegree , we estimate the distance to be 14 \pm { 2 } kpc , where we report the statistical uncertainty but note that there could be up to 20 \% variation in the distance due to systematic effects discussed in the paper .
The corresponding maximum accretion rate is 0.30 \pm 0.05 times the Eddington limit .
Based on the low hydrogen content of the accreted fuel and the short average recurrence time , we classify the source as a transient ultracompact low-mass X-ray binary .