MAXI J1915+099 / IGR J19140+0951: Swift observation
ATel #16666; J. A. Kennea (PSU) and H. Negoro (Nihon)
on 22 Jun 2024; 03:58 UT
Credential Certification: Jamie A. Kennea (kennea@astro.psu.edu)
Subjects: X-ray, Binary, Neutron Star
A detection of a either a new transient (MAXI J1915+099) or a possible outburst of IGR J19140+0951 by MAXI was reported by Serino et al. (ATEL #16665). Starting at 20:30UT on June 21, 2024, the Neil Gehrels Swift Observatory began a 4-pointing tiling of the MAXI error region of this transient, with an average exposure of 500s per tile. This tiling covered 99% of the statistical error circle. We find two X-ray sources near the edge of the MAXI error region, if systematic errors are included. One of these sources is identified as being IGR J19140+0951 in a historically bright state (0.92 +/- 0.09 XRT count/s). The other source, 2SXPS J191444.1+093759, is significantly fainter (5.2 +/- 1.3 x 10^-2 XRT count/s) with a count rate similar to previous detections.
We therefore conclude that the MAXI outburst is most likely IGR J19140+0951. The observed flux from IGR J19140+0951 is 2.74 (+1.00/-0.72) x 10^-10 erg cm^-2 s^-1, uncorrected for absorption. The source is highly absorbed, making correction for absorption and fitting of a power-law index highly uncertain, however, this flux is approximately similar, perhaps 2-3x fainter than the reported 33mCrab flux from MAXI.
