TITLE:   GCN CIRCULAR
NUMBER:  20698
SUBJECT: LIGO/Virgo G274296: SWASP optical imaging coverage
DATE:    17/02/19 09:43:20 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, J.Maund (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 G274296 (GCN #20689). Targeted observations containing ~82% of the source location probability were performed between 20:40 UT Feb 17 2017 and 06:55 UT Feb 18 2017. Each pointing consisted of 3x30s exposures in the clear filter and fields were repeated between 17 and 51 times during that observing window. These regions were also observed immeditately preceding the GW trigger as part of a survey mode program the night before with 2x30s exposures at each position between 1:21 and 6:54 UT Feb 17 2017 as well as on Feb 18 2017 between 1:14 and 6:14 UT.

Conditions were clear and stable. Typically a (5 sigma) photometric depth equivalent to V~15 was achieved per 3x30s pointing.