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GCN Circular 21969

Subject
LIGO/Virgo G299232: SWASP optical imaging coverage
Date
2017-10-04T15:25:10Z (7 years ago)
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���, J.Lyman���, P.Chote, J.McCormac (U. Warwick)  
D.K.Galloway, E.Rol, E.Thrane���, K.Ackley, A.Casey��� (Monash U.)  
V.Dhillon, M.Dyer, S.Littlefair, E.Daw, J.Mullaney���, L.Makrygianni���, J.Maund (U. Sheffield)
G.Ramsay (Armagh O.)
P.O'Brien, R.Starling���, R.Eyles��� (U. Leicester)
���S.Poshyachinda, S.Aukkaravittayapun, U.Sawangwit, S.Awiphan, D.Mkrtichian (NARIT)

On behalf of the GOTO collaboration:

We report on optical observations with the SuperWASP Exoplanet camera array on La Palma, in response to G299232 (GCN #21693). Targeted observations containing approximately 50% of the total source location probability were performed between 23:24 UT 25/08/2017 and 05:52 UT 26/08/2017. This coverage is based on the bayestar-HLV skymap with combined Ligo/Virgo constraints and is focused on the northern hemisphere region of highest probability density. Each pointing consisted of 3x30s exposures in the clear filter and pointings were repeated between 38 and 50 times during that observing window.  These regions were also observed the following night between 23:20 UT 26/08/2017 and 05:51 UT 27/08/2017.  

Observations at the same position were stacked and crossmatched with APASS for photometric calibration. Conditions were not fully stable and our 5-sigma limiting magnitudes in these stacks range from 15.9 to 17.1 (V-band equivalent). No new transients were identified in these data.

We examined our ���images��� for ���evidence of the Swift/UVOT source ���J014008.5+343403.6 (GCN #21733)���. ��� Our stacks at this position reach V=17.0 and precede the SWIFT detection. A difference image analysis shows no evidence for a source at the reported position during either of our nights of data.
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