[vsnet-grb-info 19356] GRB 170428A: DCT Imaging

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21053
SUBJECT: GRB 170428A: DCT Imaging
DATE:    17/04/30 02:40:13 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko at nasa.gov>

S. B. Cenko, E. Troja (NASA GSFC), E. Golden-Marx, E. Blanton (BU) report on behalf of a larger collaboration:

We imaged the location of the optical afterglow (Bolmer et al., GCN 21050) of the short GRB170428A (Beardmore et al., GCN 21042) with the Large Monolithic Imager mounted on the 4.3m Discovery Channel Telescope in Happy Jack, AZ.  Observations were obtained in the i-band filter beginning at 10:52 UT on 2017 April 29 (1.1 days after the GRB trigger).  We detect emission at the reported afterglow position, and measure a magnitude of i = 22.2 +/- 0.2 mag (calibrated with respect to nearby point sources from SDSS), consistent with the measurement reported by Troja et al. (GCN 21051).  We caution, however, that the candidate host galaxy (Bolmer et al., GCN 21050)  is blended with this location due to poor seeing conditions - accurate afterglow photometry may require removing this host contamination.