TITLE:   GCN CIRCULAR
NUMBER:  20388
SUBJECT: LIGO/Virgo G268556: SWASP optical imaging
DATE:    17/01/07 09:54:03 GMT
FROM:    Danny Steeghs at U of Warwick/GOTO  <D.T.H.Steeghs@warwick.ac.uk>

D. Steeghs, D.Pollacco, K.Ulaczyk, R.Cutter, R.West, A.Levan (U. Warwick), D. Galloway, E.Rol, E.Thrane (Monash U.), V. Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Mullaney (U. Sheffield), G. Ramsay (Armagh O.), P. O'Brien, R. Starling (U. Leicester)

On behalf of the GOTO collaboration:

We report on optical observations with the SuperWASP Exoplanet camera array on La Palma, in response to GCN #20364. Targeted observations containing ~45% of the BAYESTAR source location probability were performed between 21:47 UT Jan 4 2017 and 06:20 UT Jan 5 2017. Each pointing consisted of 3x30s exposures in the clear filter and fields were repeated between 20 and 35 times during that observing window. These regions were also observed as part of a survey mode program the night before with 2x30s exposures at each position between 4:37 and 6:35 UT Jan 4 2017 (4-6 hours before the event). Considering the updated LALInference map (GCN #20385), our pointings cover 40% of the total probability.

Conditions were not photometric with some variable thin clouds present. Typically a (5 sigma) photometric depth equivalent to V~15 was achieved per 3x30s pointing. Analysis is ongoing and notable source detections will be reported in a future circular.