GCN Circular 31358

A. de Ugarte Postigo (Obs. Cote d'Azur), D  A. Kann (HETH/IAA-CSIC), C. 
C. Thoene, M. Blazek (both HETH), J. F. Agui Fernandez (HETH/IAA-CSIC), 
P. Martin, and I. Hermelo (both CAHA) report:

We observed the afterglow of GRB 220101A (Swift detection: Tohuvavohu et 
al., GCN #31347; Fermi/LAT Detection: Arimoto et al., GCN #31350; AGILE 
detection: Ursi et al., GCN #31354; afterglow detections: Kuin & 
Tohuvavohu, GCN #31351; Fu et al., GCN #31353; Hentunen et al., GCN 
#31356; Perley, GCN #31357; redshift z = 4.61: Fu et al., GCN #31353) 
with CAFOS, mounted on the 2.2 m telescope, at the Calar Alto 
Observatory (Almeria, Spain). The observation started at 19:35:31 UT on 
01 January 2022 (13.47 hr after the GRB) and consisted of 6 x 90 s 
integrations in the i' band.

The afterglow is well-detected in the individual images. Against 
comparison stars from SDSS, we measure i' = 18.45 +/- 0.03 mag (AB) in 
the stacked image at mid-time 0.60177 d after the trigger.

We note this is a very bright GRB and afterglow, further follow-up is 
encouraged.