TITLE:   GCN CIRCULAR
NUMBER:  22989
SUBJECT: GRB 180706A: OSN detection
DATE:    18/07/21 05:26:20 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann, L. Izzo (both HETH/IAA-CSIC) and A. Sota (IAA-CSIC) report 
on behalf of HETH:

We observed the position of the Swift GRB 180706A (Stamatikos et al., 
GCN #22909) with the T150 telescope of the Observatorio Sierra Nevada 
(OSN) near Granada, Spain.

We obtained 6 x 300 s Ic images (mean time after trigger 0.546615 days) 
and further 5 x 300 s Ic images a night later (mean time after trigger 
1.57231 days).

The afterglow (Stamatikos et al., GCN #22909; Watson et al., GCN #22910; 
Oates et al., GCN #22922; Volnova et al., GCN #22923) is clearly 
detected in the first night, and we derive Ic = 20.56 +/- 0.06 mag. It 
is not detected anymore in the second night to a limit of Ic > 22.5. The 
detection magnitude is in good agreement with the earlier measurement of 
Volnova et al. when typical Rc-Ic colors of GRBs are taken into account.

The lead author is sorry for the long vacation this data took.