TITLE: GCN CIRCULAR NUMBER: 45376 SUBJECT: EP260812a: NOT and Liverpool Telescope upper limits: DATE: 26/08/13 15:24:20 GMT FROM: Gregory Corcoran at University College Dublin <gregory.corcoran@ucdconnect.ie> G. Corcoran (UCD), R. A. J. Eyles-Ferris (Leicester), D. B. Malesani (DAWN/NBI and Radboud), P. G. Jonker (Radboud), R. L. C. Starling (Leicester), V. Vuolteenaho (NOT / University of Oulu), K. Kisielowski (ING / University of Groningen), R. Vieliute (ING / University of St Andrews) report on behalf of a larger collaboration: We observed the field of the Einstein Probe fast X-ray transient EP260812a (Liu et al., GCN 45362) with the Nordic Optical Telescope (NOT) using the ALFOSC camera and the Liverpool Telescope (LT) using the IO:O camera. NOT observations started on 2026-08-12 at 20:52:46 UT (9.53 hr post trigger), while LT observations began on 2026-08-12 at 23:23:50 UT (12.06 hr post trigger). We do not identify any new object brighter than our reference Pan-STARRS image sensitivity limit, however our observations are deeper. We note the presence of one possible source, detected in both the NOT and LT r-band images, located at coordinates RA, Dec = 20:45:45.28, +14:09:21.3 (J2000), for which we measure a magnitude of r = 23.87 +/- 0.24 (AB) from the NOT images. However, as our observations cannot establish if this is a new source, further follow up observations are encouraged and planned. A summary of our observations is presented below. | Telescope | Mid time (hr) | Band | Exptime (s) | Limit mag (3 sigma) | | --- | -- | -- | -- | -- | | NOT | 9.66 | r| 3 x 300 | 24.11 | | NOT | 9.96 | z| 5 x 200 | 22.99 | | LT | 12.16 | r | 4 x 150 | 23.57 | | LT | 12.44 | z | 5 x 150 | 22.60 | Our photometry is in the AB system, calibrated against Pan-STARRS and not corrected for Galactic extinction. These limits are consistent with those reported by Yin et al. (GCN 45372). View this GCN Circular online at https://gcn.nasa.gov/circulars/45376. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...