B. P. Gompertz (U. Birmingham), D. B. Malesani (U. Radboud and DAWN/NBI) and A. J. Levan (U. Radboud) report:
We tiled part of the LAT localisation (Maheso et al., GCN 33780) of GRB 230512A (Fermi GBM Team, GCN 33778; Navaneeth et al., GCN 33779; Dafcikova et al., GCN 33795) with the IO:O optical camera on the 2m robotic Liverpool Telescope. XRT source 5 (Osborne et al., GCN 33789) was covered by an observation beginning on May 13, 2023 at 03:10:22 UT and consisting of a series of 6x150 s exposures in the SDSS r' filter.
We detect no source at the position of the candidate optical counterpart reported by Kitab (Belkin et al., GCN 33796) to a 3-sigma limit of r’ > 22.15, ~7.5 hours after the reported detection. We also detect the PS1 source at a magnitude consistent with the catalogued value.
No other candidate optical counterparts have been identified in our imaging, which also covers XRT sources 8 and 10, to typical limits of r' > 22. Analysis is ongoing.
Magnitudes are in the AB system, calibrated against nearby PS1 stars (Chambers et al., 2016), and are not corrected for extinction along the line of sight.