TITLE:   GCN CIRCULAR
NUMBER:  23818
SUBJECT: GRB 190129B: ePESSTO NTT optical observations
DATE:    19/01/30 16:53:05 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <paolo.davanzo@brera.inaf.it>

S. Piranomonte (INAF-OAR), R. Carini (INAF-OAR), P. D'Avanzo (INAF-OAB), D. Malesani (DAWN/NBI and DARK/NBI), J. Bolmer (MPE, Garching), A. Melandri (INAF-OAB), T.-W. Chen (MPE), M. Nicholl (Univ. Edinburgh), S. C. Williams (Univ. Lancaster), S. Benetti (INAF-OAPd), L. Tomasella (INAF-OAPd), A. Fiore (Univ. Padova and INAF-OAPd), C. Inserra (Cardiff), E. Kankare (Turku), K. Maguire (QUB), S. J. Smartt (QUB), O. Yaron (Weizmann), D. R. Young (QUB), I. Manulis (Weizmann) report:

We observed the location of the candidate X-ray afterglow (LaPorte et al., GCN 23813) of the IPN-detected GRB 190129B (Hurley et al., GNC 23808; Frederiks et al., GCN 23809), 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 (NTT) at La Silla with the EFOSC2 instrument, starting on 2019 Jan 30 at 07:12:54 UT (i.e. 18.9 hr after the burst). Two images were acquired in the r band, by 120 and 240 s, respectively. The seeing conditions were unfortunately poor (~2”).

We confirm a low-S/N detection of the object visible in the Pan-STARRS images, as reported by Bolmer & Steinle (GCN 23814).

Astrometry and photometry of this object are unfortunately affected by the presence of a nearby source ~2" to the SE, which is most likely a ghost from an 11-th magnitude star in the field of view. As this object is not seen in nearly-simultaneous GROND images of comparable depth (J. Bolmer, priv. comm.), we conclude that it is likely an artefact.