GRB 210306A after glow observed

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GRB 210306A after glow observed with iTelescope T24 remote telescope. Photo by: Markku Nissinen.

GRB 210306A. Photo by: Markku Nissinen.

 

Full GCN Circular https://gcn.gsfc.nasa.gov/gcn/gcn3/29603.gcn3 and below.

TITLE:   GCN CIRCULAR
NUMBER:  29603
SUBJECT: GRB 210306A: iTelescope T24 optical observations
DATE:    21/03/06 14:23:19 GMT
FROM:    Veli-Pekka Hentunen at Taurus Hill Obs,A95

Veli-Pekka Hentunen and Markku Nissinen (Taurus Hill Observatory, Varkaus, Finland) report:

We have detected GRB 210306A optical afterglow using iTelescope T24 (0.61-m f/6.5 + CCD) telescope in Sierra Remote Observatory (Auberry, California, USA). The observations were started at 2021-03-06 05:02:41 (UT). We used Luminance filter and 300 sec exposures. 

The afterglow was detected at the position RA 08 39 50.11 DEC +60 12 18.8.  The following magnitudes were measured from comparison of  a nearby star (r = 16.974) from Pan-STARRS DR1 catalogue (Chambers et al., 2016):

Tmid (h:min:sec)+T0    Mag     Mag_err            
01:11:12                      18.08   0.08
01:16:55                      17.97   0.06
01:22:47                      18.13   0.07
02:06:55                      18.41   0.10
02:14:53                      18.44   0.09
02:18:53                      18.52   0.10
02:24:37                      18.63   0.10
03:03:34                      18.82   0.11
03:09:13                      18.85   0.11
03:20:45                      18.87   0.12
03:26:56                      18.91   0.12
03:32:55                      18.84   0.13
04:33:44                      19.33   0.19
04:39:39                      19.22   0.18
05:03:57                      19.33   0.21
05:27:40                      19.61   0.38

Magnitudes were not corrected for galactic extinction.