[vsnet-grb-info 21000] GRB 180806A: NOT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23098
SUBJECT: GRB 180806A: NOT optical observations
DATE:    18/08/08 02:13:55 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at dark-cosmology.dk>

Daniele Bjørn Malesani (DAWN/NBI and DARK/NBI) and Ana Sagues (NOT) report:

We observed the candidate optical counterpart (Lipunov et al., GCN 
23091; Watson et al., GCN 23092) of the Fermi GRB 180806A (Malacaria et 
al., GCN 23095) using the Nordic Optical Telescope (NOT) equipped with 
the AlFOSC camera.

In a single 300 s exposure centered on 2018 Aug 8.07 UT (27.09 hr after 
the GRB), we detect the candidate afterglow with a magnitude r = 22.31 
+- 0.10 AB, calibrated against nearby stars from the Pan-STARRS catalog.

The continued fading compared to previous reports (Lipunov et al., GCN 
23091; Butler et al., GCN 23094; Watson et al., GCN 23096), as well as 
the spatial coincidence with an X-ray source (Gibson et al., GCN 23097) 
confirm the interpretation of this source as the optical afterglow of 
GRB 180806A.