Search for the optical counterpart of the transient Swift J151857.0-572147
ATel #16516; Payaswini Saikia, D. M. Russell (NYUAD), M. C. Baglio (INAF-OAB), Kevin Alabarta, S. Rout (NYUAD), F. Lewis (Faulkes Telescope Project & Astrophysics Research Institute, LJMU)
on 8 Mar 2024; 19:23 UT
Credential Certification: Payaswini Saikia (ps164@nyu.edu)
Subjects: Optical, Transient
Swift J151857.0-572147 is a newly discovered X-ray transient that was previously thought to be a Gamma Ray Burst (GRB 240303A; GCN #35849, #35835), but was soon confirmed to be a galactic X-ray transient by repeated observations with Swift (ATel #16500). The radio and the infrared counterparts of the source were discovered at the coordinates RA(J2000)=15:18:57.5, Dec(J2000)=-57:21:48.7 with MeerKAT (ATel #16503) and the Robotic Eye Mount (REM) telescope (ATel #16506). It was not detected at optical frequencies with REM (ATel #16506).
Here, we report optical observations of the field of Swift J151857.0-572147 with the Las Cumbres Observatory (LCO) network. Images were taken soon after the Swift/XRT discovery, in the i'-band with the 1-m and 2-m nodes at Siding Spring, Australia (including the 2-m Faulkes Telescope South) and the Cerro Tololo Inter-American Observatory, Chile on 2024 March 4, 5 and 6. We do not detect the source at the coordinates provided by the previous ATels (ATel #16500, ATel #16503 and ATel #16506), probably owing to the high extinction towards it (N_H = 5.6 +/- 0.1 x 10^22 cm^-2; ATel #16500). We flux calibrate the field using APASS catalog and constrain an optical upper limit of i'>20.67 mag.
These observations are part of a monitoring campaign of ~50 low-mass X-ray binaries in the optical wavelengths (Lewis et al. 2008). We encourage multi-wavelength observations of the source.
