GCN Circular 29819
Swift/BAT did not successfully trigger on GRB 210413B (T0: 2021-04-13 23:46:52.45 UTC, Fermi/GBM TRIGGER 640050417). The GUANO system is currently offline, thus no extended GUANO data is available for this time, and so the sensitive GUANO MLL analysis (DeLaunay et al. 2021, in prep) can not be run. Swift/BAT triggered in real-time onboard in the rates domain (trigger #1043009), but no strong source was found to be associated in the onboard imaging. This 'failed trigger' resulted in 10s of BAT TTE data being saved and sent to the ground. The duration of the burst, as seen by BAT, is T90 = 1.088 s +/- 0.09 s. In ground analysis of the available TTE data, we find a source using typical imaging analysis, that is the likely location of the GRB, with SNR 6 in the image domain. The BAT position is RA, Dec = 182.558 +55.965, which is: RA (J2000) 12h 10m 13.920s Dec (J2000) +55d 57' 54.00" with an estimated uncertainty of 3 arcminutes. This location is consistent with the Fermi/GBM localization distributed in the Final Position notice. XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars.