GCN Circular 35853

J. A. Kennea (PSU), A. Y. Lien (U Tampa) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team:

Swift Trigger #1218452 (GCN #35849), previously named GRB 240303A but considered likely to be a galactic transient named Swift J151857.0-572147, has been confirmed to be a transient. Repeated observations of the source show it to be consistently bright, with no signs of fading. This combined with its localization within the Galactic Plane, and the fact that this was a BAT Image trigger, confirms its nature as a Galactic Transient.

A spectral fit to the combined Swift/XRT data show an absorption N_H = 5.6 +/- 0.06 x 10^22 cm^-2 and a power-law slope with photon index of 1.78 +/- 0.02. The average flux, corrected for absorption is 1.40 +/- 0.02 x 10^-8 erg/s/cm^2 (0.5-10 keV).

We encourage follow-up observations in order to determine the nature of this new transient.