[vsnet-grb-info 13261] GRB 130427A, Watcher afterglow detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14598
SUBJECT: GRB 130427A, Watcher afterglow detection
DATE:    13/05/07 22:00:53 GMT
FROM:    Martin Topinka at UCD, Dublin  <martin.topinka at gmail.com>

Martin Topinka, Lorraine Hanlon, Pete Tisdall, Seamus Meehan, Antonio Martin-Carrillo (UCD, Dublin) and Petr Kubánek (FZÚ AVČR, Praha) on behalf of the Watcher telescope team, report:

We followed the Swift detection of GRB 130427A (Maselli et al., GCN 14448, Swift trigger 554620) with the Watcher robotic telescope (D=40cm) located at Boyden Observatory, near Bloemfontein in South Africa.

We started imaging the field at 16:43:55 UT on 2013-04-27 (i.e. 8.9 hr after the BAT trigger) taking 2 minute exposures in the clear filter using an Andor CCD camera.

The optical afterglow (Elenin et al., GCN 14450) is clearly detected. Preliminary analysis of some of the initial images gives a magnitude for the optical afterglow of 16.59+/-0.04 @ 17:00:35 UT and 16.79+/-0.07 @ 18:59:13 UT.

Magnitudes were estimated using several nearby USNO-B1 stars as references and are not corrected for galactic dust extinction. Further analysis of these images is on-going. The field continues to be regularly observed with Watcher.

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