TITLE:   GCN CIRCULAR
NUMBER:  32107
SUBJECT: GRB 220521A: BOOTES-2/TELMA and CAHA 2.2m telescope optical upper limit
DATE:    22/05/24 15:14:20 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, T.-R. Sun, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez, I. Perez-Garcia (IAA-CSIC), I. Vico, S. Cikota (CAHA), C. Perez del Pulgar, A. Castellon, M. A. Castro Tirado (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:

Following the detection of GRB 220521A by Fermi (GBM team GCNC 32075) and Swift (Dichiara et al. GCNC 32076), the 0.6m BOOTES-2/TELMA robotic telescope in Algarrobo Costa (Malaga, Spain) automatically respond to this event and pointed to the Swift/XRT position (Evans et al. GCNC 32077) on May 21, 23:20:56 UT (35 s post trigger). Due to the cloudy weather, only useful frames were obtained starting at 23:39:23 UT (i.e. ~19 min after trigger). The afterglow detected by both XRT and NOT is not detected in our co-added image (60 x 23 s, clear filter), down to 18.4 mag.

Later on, we also triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain). Images (Sloan i-band) were gathered since May. 23 01:36 UT (i.e. 1.1 day post trigger). On the co-added image (14 x 180 s), the afterglow is not detected down to i = 24.1 mag.

Those non-detections are consistent with the previous reports from NOT (Malesani et al. GCNC 32078, Fynbo et al. GCNC 32079), SAO (Goranskij et al. GCNC 32082), RATIR (Watson et al. GCNC 32087), Sintesz-Newton (Nazarov et al. GCNC 32088), LCO (Strausbaugh et al. GCNC 32091), REM (Ferro et al. GCNC 32096), MMT (Rastinejad et al. GCNC 32097), Gemini (Cucchiara et al. GCNC 32099), MITSuME (Sato et al. GCNC 32101) and ISON-Castelgrande (Belkin et al. GCNC 32103).

We thank the staff at IHSM/UMA-CSIC La Mayora and CAHA for their excellent support.