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GCN Circular 30856

Subject
GRB 210919A: LOAO and LSGT optical upper limits
Date
2021-09-20T08:00:38Z (3 years ago)
From
Sophia Kim at Seoul National U. <sophiak@astro.snu.ac.kr>
GRB 210919A: LOAO and LSGT optical upper limits


Sophia Kim (Seoul National University, SNU), Myungshin Im (SNU); Jeff Cooke
(Swinburne University of Technology), Gu Lim (SNU); report on behalf of
IMSNG & GECKO Collaboration


We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al.
GCNC #30846) with the 1-m telescope at Mt. Lemon Optical Astronomy
Observatory (LOAO) in US Arizona. Observations began on September 19 at
10:42:02 UT , ~10.23 hours after the GRB trigger. We took 19 X 180s
exposures in Johnson R-band.

We also observed the same field with the 0.43-meter (17 inch) Lee Sang Gak
Telescope (LSGT) located at the Siding Spring Observatory (SSO) in
Australia. Imaging began on the same day at 16:12:53 UT, ~15.73 hours after
the GRB trigger. The observations were performed in a Sloan r-, i- and
z-band sequences with 11 X  300s exposures in each band.


No GRB optical counterpart was found in the LOAO and LSGT data within the
XRT error area (M. R. Goad et al. GCNC #30850). This result is consistent
with the optical observational results by other teams (V. Lipunov et al.
GCNC #30847, Y.-D. Hu et al. GCNC #30848, R. Strausbaugh et al. GCNC
#30849, M.R. Goad et al. GCNC #30850, N. Pankov et al. GCNC #30851, D. A.
Perley et al. GCNC #30852, M. Perri et al. GCNC #30854 and Y.Takamatsu et
al. GCNC #30855).


The following is our observation results.

We calibrated flux with the PS1 catalog and used AB magnitude system. (The
magnitudes are not corrected for extinction.)


#--------------------------------------------------------------------------------------------------------------

OBS/TEL DATE-OBS(UT) FILTER EXPT UL(3��)[ABmag] UL(5��)[ABmag]

LOAO/1-m 2021-09-19T10:42:02 R 3420s >21.716  >21.162

SSO/LSGT 2021-09-19T16:12:53 r 3300s >20.160  >19.605

SSO/LSGT 2021-09-19T16:18:17 i 3300s >19.107  >18.553

SSO/LSGT 2021-09-19T16:23:53 z 3300s >18.674  >18.119

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[GCN OPS NOTE(20sep2021):  Per author's request, the signiture block
that is automatically added to the bottom has been removed.]