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GCN Circular 32739

GRB 221009A: Lowell Discovery Telescope Afterglow Detection
2022-10-13T17:07:17Z (2 years ago)
Brendan O'Connor at UMD <>
B. O'Connor (UMD/GWU), S. B. Cenko (NASA/GSFC), E. Troja (UTV/ASU),
S. Dichiara (PSU), A. Kutyrev (NASA/GSFC), S. Veilleux (UMD),
J. Durbak (UMD), on behalf of a larger collaboration:

We performed target of opportunity observations of GRB 221009A
(Dichiara et al., GCN 32632, Veres et al., GCN 32636)
with the 4.3m Lowell Discovery Telescope in Happy Jack, AZ.
Observations began on October 13, 2022 at 03:09:27 UT corresponding
to ~3.6 d after the GRB. We obtained images in the griz filters at
an airmass ~1.2 with seeing ~1.2".

The afterglow is clearly detected in all filters. We obtain the
following magnitudes calibrated against the PS1 catalog:

r = 20.44 +/- 0.02 AB mag
i = 19.37 +/- 0.01 AB mag

Compared to observations at 63 hr (Watson et al., GCN 32705)
the temporal decay has a power-law index of about -0.9,
shallower than observed in X-rays.

These magnitudes are not corrected for Galactic extinction.

We thank the staff of the Lowell Observatory for assistance
with these observations.
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