In 2000 September we observed a bright X-ray burst from X2127 + 119 with the Rossi X-ray Timing Explorer .
This burst has a multi-peaked profile , a peak luminosity of \sim 6.5 \times 10 ^ { 38 } erg s ^ { -1 } , a total integrated energy of \sim 2 \times 10 ^ { 40 } ergs , and significant photospheric radius expansion to a maximum extent of R =118 \pm 5 km .
From the luminosity-temperature relation during the expansion phase we derive estimates for the gravitational redshift at the neutron star surface , the corrected Eddington luminosity , and the neutron star mass .
We detect no slow ( \sim 30s ) radial oscillations or fast ( 100–1200 Hz ) coherent oscillations or QPO during the burst .

The 2000 September event is only the second burst ever observed from this globular cluster binary ( in M15 = NGC 7078 ) , and it shares many characteristics with the event detected by Ginga in 1988 October ( Dotani et al .
1990 ; van Paradijs et al .
1990 ) , the key difference probably being the total amount of material consumed in the thermonuclear flash .