TITLE:   GCN CIRCULAR
NUMBER:  33434
SUBJECT: GRB 230307A: optical upper limit
DATE:    23/03/09 09:51:32 GMT
FROM:    Alberto J. Castro-Tirado at IAA-CSIC  <ajct@iaa.es>

I. Pérez-García (IAA-CSIC Granada, Spain), A. Maury (Space Obs, Chile), 
E. Fernández-García, Y.-D. Hu and A. J. Castro-Tirado (IAA-CSIC and 
UMA), on behalf of a larger collaboration, report:

“Following the detection of the very bright GRB 230307A (Burns et al. 
GCNC 33414) by Fermi/GBM (the Fermi GBM team, GCNC 33405; Dalessi, GCNC 
33407; Dalessi and Roberts, GCNC 33411), GECAM (Xiong et al., GCNC 
33406), Solar Orbiter/STIX (Xiao and Krucker, GCNC 33410), AGILE/MCAL 
(Casentini et al., GCNC. 33412), INTEGRAL/SPI-ACS, Mars-Odyssey/HEND 
(Kozyrev et al. GCNC 33413), AstroSat/CZTI (Navaneeth et al. GCNC 
33415), GRBAlpha (Dafcikova et al. GCNC 33418), VZLUSAT-2 (Ripa et al. 
GCNC 33424), Konus-WIND (Svinkin et al. GCNC 33427) and Swift-BAT 
(Tohuvavohu, GCNC 33431), we observed 60% of the preliminary IPN error 
box (Kozyrev et al. GCNC 33413) with a 0.5m wide-field telescope in the 
vicinity of the BOOTES-7 astronomical station at San Pedro de Atacama 
Space Observatory. No optical candidate down to 17.4 mag is found on the 
images (clear filter, 1.6h co-add) starting at 4:36 on Mar 8 UT (i.e. 
12.9 h postburst) within the entire improved IPN position (Kozyrev et 
al. GCNC 33425).”

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