TITLE:   GCN CIRCULAR
NUMBER:  27749
SUBJECT: Swift J1818.0-1607: BOOTES-3/YA optical upper limit
DATE:    20/05/17 11:11:57 GMT
FROM:    Youdong HU at IAA-CSIC  <youdong@iaa.es>

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado (IAA-CSIC), I. 
Carrasco and C. Perez del Pulgar (Univ. de Malaga), M. D.
Caballero-Garcia (ASU-CAS, CZ) and R. Querel (NIWA), on behalf of a 
larger collaboration,
report:

The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New 
Zealand) automatically responded to the Swift trigger of SGR Swift 
J1818.0-1607 (Gronwall et al. GCNC 27746). The first image (clear 
filter) were obatined starting at 15:03:57 UT(~ 29 s after trigger). In
the co-added image (79 exposures, 1s each), no source is found at the 
position reported by Swift/XRT (Gronwall et al. GCNC 27746) down to 18.5 
mag, which is in agreement with the non-detection reported by Lipunov et 
al. (GCNC 27747). Further observation is ongoing.

We thank the staff at NIWA for its excellent support.