TITLE:   GCN CIRCULAR
NUMBER:  23133
SUBJECT: GRB 180809B: ePESSTO NTT NIR observations
DATE:    18/08/12 14:02:05 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

Z. Kostrzewa-Rutkowska (SRON/RU), E. Callis (UCD), R. Stein (HU Berlin/DESY), P. D'Avanzo (INAF-OAB), M. Fraser (UCD), J. Lyman (Warwick), D. B. Malesani (DAWN/NBI and DARK/NBI), C. Inserra (Southampton), E. Kankare (QUB), K. Maguire (QUB), S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), I. Manulis (Weizmann) report:

We observed the field of GRB 180809B (Moss et al., GCN Circ. 23105) under the extended Public ESO Spectroscopic Survey for Transient Objects (ePESSTO; see Smartt et al. 2015, A&A, 579, 40 http://www.pessto.org <http://www.pessto.org/> ). The observations were performed on the ESO New Technology Telescope at La Silla with the SofI instrument in imaging mode starting on 2018-08-12 between 03:38 and 04:27 UT (i.e. about 2.298 and 2.332 days from the burst) with the H filter.

The NIR counterpart (Schweyer et al. GCN Circ. 23111) is clearly detected. From preliminary photometry, we estimate a magnitude of H ~ 20.3 (Vega, calibrated against the 2MASS catalogue). Compared to earlier reports (Schweyer et al. GCN Circ. 23111), our measure indicates significan fading. However, we cannot assess if we already reached the host galaxy level.