GCN Circular 26565
Subject
GRB 191221B: iTelescope optical observations
Event
Date
2019-12-23T00:21:24Z (6 years ago)
From
Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>
I observed the optical afterglow of GRB 191221B (Laha et al., GCN Circ.
26534) with remote telescope T32 (0.43-m f/6.8 reflector + FLI Proline
16803 CCD) of iTelescope.Net in Siding Spring Observatory (Australia) on
2019-12-22 since 13:28:52 UT (~16.8 hours after the trigger). Two images
were obtained in each band with Astrodon luminance filter and
Johnson/Cousins V filter for 180 and 120 seconds (Binx2). I detected the
optical afterglow in three images in the enhanced Swift-XRT position
(Beardmore et al., GCN Circ. 26540); it not present in images from DSS
Plate Finder.
The following magnitudes (mag. error ~ 0.2) were measured from comparison
to nearby stars from APASS DR9 catalogue (Henden et al., 2016):
Time of start Exp.time Mag. Comp.star band Filter
----------------------------------------------------------
13:28:52 UT 180 s 18.1 r' Luminance
13:32:58 UT 180 s 18.3 V V
13:36:51 UT 120 s 18.3 r' Luminance
13:39:46 UT 120 s <17.9 V V
----------------------------------------------------------
Magnitudes were not corrected for Galactic extinction.