TITLE:   GCN CIRCULAR
NUMBER:  27980
SUBJECT: IceCube-200530A - SN2020lls likely unrelated
DATE:    20/06/18 13:53:49 GMT
FROM:    Simeon Reusch at DESY  <simeon.reusch@desy.de>

Simeon Reusch, Robert Stein, Anna Franckowiak, Jannis Necker (DESY),
Jesper Sollerman, Cristina Barbarino and Tassilo Schweyer (Stockholm
University) report:

We observed ZTF candidate SN2020lls (Reusch et al, GCN 27872), a
possible counterpart to high-energy neutrino IceCube-200530A (Stein et.
al, GCN 27865), using the NOT/ALFOSC spectrograph on 12 June 2020.

We classify SN2020lls as a Type Ic supernova without broad-line features.

SN2020lls was detected with forced photometry by ZTF in i-band images 1
day prior to neutrino detection. An explosion time estimator puts the
supernova explosion time 8 (+5/-2) days prior to neutrino detection.
Both points suggest that the neutrino was detected several days after
explosion.  

The apparent delay between supernova explosion and neutrino detection is
inconsistent with a choked-jet neutrino production scenario. Therefore,
SN2020lls is likely not related to the high-energy IceCube neutrino
IceCube-200530A.

AT2019fdr remains a source candidate.