GCN Circular 30884
Subject
GRB 210919A OSN 1.5m Source Confirmation
Date
2021-09-26T23:01:27Z (3 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez
(all HETH/IAA-CSIC), and F. Aceituno (IAA) report:
We obtained observations of the enhance XRT position (Goad et al., GCN
30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846)
with the 1.5m telescope of OSN, Granada, Spain. We obtained 35 x 120 s
images in the Rc band, starting at 03:28:22 UT on September 19, under
good observing conditions. We obtained a second epoch, with 41 x 120 s
images, the following night, starting at 2:59:51 UT on September 20.
The source detected by Kann et al. (GCN #30883) is very faintly detected
in the first epoch.
Using the same comparison stars from the PanSTARRS catalog as used by
Kann et al. (GCN #30883) (transformed to Rc via the Lupton equations,
then transformed back to AB magnitudes), we measure:
Rc = 24.47 +/- 0.53 mag @ 0.14944 d after trigger (AB mag).
The source is undetected in the second epoch, but it is shallower, with
Rc > 23.6 mag (AB) @ 1.13649 d after the GRB. We note this detection is
also fainter than the upper limits listed in Kann et al. (GCN #30883).