TITLE:   GCN CIRCULAR
NUMBER:  32771
SUBJECT: GRB 221009A: Faulkes Telescope North continued optical afterglow follow-up 
DATE:    22/10/16 21:35:11 GMT
FROM:    Manisha Shrestha at University of Arizona  <mshrestha1@arizona.edu>

M. Shrestha (Univ. of Arizona), K. Bostroem (Univ. of Arizona),  D. Sand (Univ. of Arizona), K. D. Alexander (Univ. of Arizona), J. Andrews (Gemini), J. Pearson (Univ. of Arizona), G. Hosseinzadeh (Univ. of Arizona), N. Smith (Univ. of Arizona), D. A. Howell (LCO/UCSB), C. McCully (LCO/UCSB), M. Newsome (LCO/UCSB), E Padilla Gonzalez (LCO/UCSB), C. Pellegrino (LCO/UCSB), G. Terreran (LCO/UCSB), J. Farah (LCO/UCSB) report on behalf of a wider Global Supernova Project collaboration:



We observed the field of Swift GRB 221009A (Dichiara et al. GCN 32632 ) with Faulkes Telescope North, on 2022 October 15 starting at 6:34:12.198 UT (~5.7 days after the trigger) using the MuSCAT3 imager in the r, i, and z bands.  Data were calibrated with respect to nearby PanSTARRS sources for r, i, and z bands .



We clearly detect the optical counterpart in the r, i and z bands and obtain an upper limit on the g band. The magnitudes are as follows:



r  = 21.13 +- 0.06

i  = 20.01 +- 0.05

z = 19.39 +- 0.05



These values are not corrected for galactic extinction and are consistent with the magnitudes reported in Belkin et al. GCN 32769 observed in a similar time frame.