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GCN Circular 22188

GRB 171205A: LSGT optical afterglow follow-up observation
2017-12-06T13:17:04Z (6 years ago)
Myungshin Im at Seoul Nat U <>
Changsu Choi, Myungshin Im (CEOU/SNU), on behalf of a larger collaboration

We observed the field of GRB 171205A (D'Elia et al., GCN 22177) with
SNUCAM-II (Choi & Im 2017, JKAS, 50, 71) on the 0.43m Lee Sang Gak
Telescope (LSGT; Im et al. 2015, JKAS, 48. 207) at the Siding Spring
Observatory in Australia. The observation started at about 9 hours after
the BAT alert, using r, i, z (broad-band), m425, m475, m525, m575, and m625
(medium-band) filters.

We clearly identify the optical afterglow in these bands, and preliminary
photometry results in r, i, and z filters are reported below. Note that the
photometric calibration is based on stars from the Pan-Starrs catalog in
the vicinity of GRB 171205A, and systematic errors due to host galaxy
subtraction uncertainty could amount to a few tenths of magnitude.

Filter Mag err UT(center)

r18.0 0.1 2017-12-05T16:17:17

i 18.1 0.1 2017-12-05T16:26:55

z 18.3 0.2 2017-12-05T16:36:33

Further observations and analysis are being carried out.
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