GCN Circular 30834
Subject
GRB 210912A: CAHA 2.2m Detection
Event
Date
2021-09-13T09:35:41Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all
HETH/IAA-CSIC), and S. Gongora (CAHA) report:
We observed GRB 210912A (Swift detection: Troja et al., GCN #30820) with
CAFOS mounted on the 2.2m CAHA telescope at Calar Alto, Almeria, Spain.
We obtained 7 x 60 s in the SDSS i' band under passing clouds, starting
at 20:04:34 UT (9.056 hrs after the trigger; further observations at a
later time were prevented by cloud cover). The afterglow (Hu et al., GCN
#30823; Pankov et al., GCN #30825; Kuin & Troja, GCN #30832) is faintly
detected in the stacked image.
Compared to a nearby Pan-STARRS comparison star, we measure (AB mag) i'
= 21.66 +/- 0.15 mag at 0.38146 d after the GRB, further confirming the
decaying afterglow. This is still significantly brighter than the
potential underlying host galaxy (Kann, GCN #30829).