TITLE: GCN CIRCULAR NUMBER: 39043 SUBJECT: GRB 250127A: LCO optical upper limit DATE: 25/01/27 09:58:37 GMT FROM: Damien Turpin at CEA-Saclay dturpin-astro@hotmail.com
D. Turpin, J. T. Palmerio, A. Saccardi (CEA), B. Schneider (LAM), S. Basa (UAR Pytheas, OHP, LAM), S. Vergani (GEPI/Obs. de Paris), E. Le Floc'h (CEA), C. Wu, L.-P Xin (NAOC) on behalf of a larger collaboration.
We observed the field of GRB 250127A detected by SVOM (Wu et al., GCN 39041) with the Sinistro instrument mounted on the 1-m telescope of the LCO network and the SCICAM QHY600 camera mounted on the 40 cm telescope, located at the Cerro Tololo, Chile. Our observation started at 2025-01-27T07:12:38.385 UTC (2.13 hr after the trigger) with a series of 2 x180s images using the PS1-z filter and 4 x 180s exposure using the sdss-r filter.
We did not detect any uncatalogued optical source inside the SVOM/ECLAIRs error region. We derived the preliminary following upper limit z > 17.8 (T-TGRB = 2.23h ,midtime) and r > 22.1 (T-TGRB = 2.32h ,midtime) given at 5 sigma (AB system) calibrated with the PanSTARRS DR2 catalog and not corrected for galactic extinction.
At the time of our observations, we note the presence of the minor planet designated as 2007 RT45 at RA, DEC (J2000): 11:18:42.1, +03:21:34 just outside the SVOM/ECLAIRs localisation error region.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004719.
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