GCN Circular 29747
Subject
GRB 210402A: Montarrenti Observatory upper limit
Event
Date
2021-04-03T07:17:41Z (5 years ago)
From
Simone Leonini at Monarrenti Obs <s.leonini@iol.it>
Simone Leonini, M. Conti, P. Rosi and L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:
We observed the field of GRB210402A (Swift trigger 1040123, Fermi trigger 639093861, K.L. Page et al., GCN Circ. 29743) with the automatic 0.53m RC telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started at 2021-04-02 22:48:18 UT (18 minutes post-burst) stacking 4 unfiltered CCD exposures of 40s each.
We have not found optical transient within the error-box given.
Mag. upper limit R = 20.10+/-0.19
Magnitudes were obtained using Astrometrica software using USNO-B1 catalogue and are not corrected for galactic extinction.