Discovery of X-ray bursts from two sources in Aquila
Two X-ray burst sources have been discovered in Aquila with the aid of the SAS 3 X-ray Observatory; MXB 1906 + 00 and Aql MXB. The present paper reports on source positions, spectra, time structure, and burst energy. Five bursts were detected from MXB 1906 + 00, and the data are shown to be consistent with the assumption that there was a burst about every 8.9 hr. A comparison of raw counting data for three bursts indicates that the bursts were detected in the energy range from 1.3 to 19 keV and that the spectrum softened during burst decay. The spectrum of the one burst observed from Aql MXB is found not to soften during burst decay. It is suggested that MXB 1906 + 00 and the previously known 'steady' source A 1905 + 00 are very likely to be the same source and that the ratio of time-averaged 'steady' luminosity to time-averaged burst luminosity would be approximately 80.