LEIA detected possible brightening of SAX J1747.0-2853 and X-ray variability of 1A 1742-294 in the Galactic Center region, where MAXI reported the detection of a new X-ray outburst since May 24 2023(ATel #16059). The Galactic Center region has been regularly monitored by LEIA in the last few months. In the latest observations taken on May 26 2023, within the field of view (1.5 degrees, FWHM) of MAXI/GSC detection ((l, b) = (359.944, -0.046)), LEIA detected two sources at (RA=266.782, Dec=-28.85, uncertainty=2.6 arcmin) and (RA=266.535, Dec=-29.499, uncertainty=2.2 arcmin), that are spatially consistent with SAX J1747.0-2853 and 1A 1742-294, respectively.
SAX J1747.0-2853 remained undetected in all previous observations of LEIA with a typical cadence of ~10 days and a typical exposure time of ~700s, indicating an upper limit of ~4e-11 erg/s/cm2; whereas an X-ray source was detected around this position in the last two observations at 2023-05-26T05:28:30 and 2023-05-26T07:02:48. Assuming the source is indeed SAX J1747.0-2853 and a spectral shape of absorbed powerlaw with a photon index of 2.0 and NH of 7e+22 cm^-2 (Wijnands et al. 2002, ApJ, 579, 422), its unabsorbed 0.5-4 keV flux was (3.5+/-1.2)e-9 erg/s/cm2 and (9.3+/-7.0)e-10 erg/s/cm2, respectively, implying that SAX J1747.0-2853 has entered a new outburst.
The other source was firstly detected by LEIA on May 12 2023. Assuming it is 1A 1742-294 and a spectral shape of absorbed powerlaw with a photon index of 2.0 and NH of 6e+22 cm^-2 (Lutovinov et al. 2000, arXiv:astro-ph/0009349), its unabsorbed 0.5-4 keV flux was (1.8+/-1.0)e-9 erg/s/cm2. During the following observations till May 26 2023, 1A 1742-294 shows moderate variability with its 0.5-4 keV unabsorbed flux varies in the range of ~6e-10 to 3e-9 erg/s/cm2.
The preliminary results have been posted at Astronomer's Telegram as ATel 16061. Click here for more EP/LEIA Astronomer's Telegrams.