TITLE: GCN CIRCULAR NUMBER: 31949 SUBJECT: Correction to 31937: GRB 220421B: Detection by VZLUSAT-2 DATE: 22/04/25 16:52:18 GMT FROM: Jakub Ripa at Masaryk University J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), M. Ohno (Eotvos U./Hiroshima U.),  N. Werner  (Masaryk U.),  L. Meszaros (Konkoly Observatory), H. Takahashi (Hiroshima U.), B. Csak (Konkoly Observatory), M. Topinka, F. Munz, F. Hroch (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration. In Ripa et al. GCN 31937 we reported a detection of the GRB 220421B. Based on the GOES-16 and GOES-17 X-ray data the reported burst is probably not a GRB but a solar flare. The GOES X-ray light curves show a peak at 2022-04-21 21:04:00 UT which coincides with the peak in the rate curves from the GRB detectors on board the VZLUSAT-2 nanosatellite. The Sun was in the field of view of the VZLUSAT-2/GRB detectors. We apologize for any inconvenience.