TITLE:   GCN CIRCULAR
NUMBER:  44807
SUBJECT: EP260602a: GTC and Liverpool Telescope optical observations
DATE:    26/06/03 16:41:18 GMT
FROM:    Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>

D. B. Malesani (DAWN/NBI and Radboud), R. A. J. Eyles-Ferris (Leicester), J. N. D. van Dalen (Radboud), P. G. Jonker (Radboud), R. L. C. Starling (Leicester), A. J. Levan (Radboud & Warwick), J. Chacón (PUC), I. Yanes (GTC), A. Tejero (GTC), S. Geier (GTC) report on behalf of a larger collaboration:

We observed the field of EP260602a (Li et al., GCN 44770) with the Gran Telescopio Canarias (GTC) and the Liverpool Telescope (LT), both on the island of La Palma, equipped with the OSIRIS+ and IO:O instruments, respectively. Observations were performed in the Sloan r and z filters. We detect the optical/NIR counterpart (Xu et al., GCN 44781; Watson et al., GCN 44790; Li, GCN 44794; He et al. GCN 44798) in the GTC r and z stacked images, and marginally in the LT r image.

We obtain the following photometry for the counterpart, calibrated to Pan-STARRS and not corrected for Galactic extinction:

| t_mid - t_0 (hours) | Telescope/instrument | Filter | Exposure (s) | AB magnitude |
| --- | --- | --- | --- | --- |
| 16.7 | LT/IO:O | r | 7x150 | 22.62 +/- 0.29 |
| 17.0 | GTC/OSIRIS+ | r | 10x60 | 23.20 +/- 0.10 |
| 17.1 | GTC/OSIRIS+ | z | 10x45 | 22.70 +/- 0.10 |
| 17.4 | LT/IO:O | z | 4x150 | >22.15 |