TITLE:   GCN CIRCULAR
NUMBER:  25585
SUBJECT: GRB 190829A: Liverpool Telescope optical photometry
DATE:    19/08/31 03:50:09 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley and A. M. Cockeram (LJMU) report:

We obtained observations of the afterglow of GRB 190829A (Dichiara et 
al., GCN 25552; Lesage et al., GCN 25575; Xu et al., GCN 25555) with the 
IO:O imager on the 2m robotic Liverpool Telescope.  Two epochs of 
imaging in the u, g, r, i, and z filters were acquired on 2019-08-30 UT 
(at approximately 03:33 and 05:01) plus one epoch of g, r, in and z 
imaging on 2019-08-31 UT (starting at 02:27).  The afterglow is clearly 
detected in griz in all three epochs.  It is not detected in u-band.

For our most recent epoch, we report the following magnitudes after 
subtraction of the presumptive host galaxy using PS1 catalog images 
(times relative to the Swift trigger, in days):

  t-t0    filt   mag       unc
  ------  ----   -----     ----
  1.2715    i  = 20.75 +/- 0.10
  1.2809    g  = 22.45 +/- 0.21
  1.2903    r  = 21.65 +/- 0.10
  1.2996    z  = 19.88 +/- 0.06

Further observations are planned.










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