Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
Introducing Einstein Probe, Astro Flavored Markdown, and Notices Schema v4.0.0. See news and announcements

GCN Circular 29165

GRB 201223A: iTelescope optical afterglow observations
2020-12-24T02:49:44Z (3 years ago)
Filipp Dmitrievich Romanov at Amateur astronomer <>
I observed the field of GRB 201223A (Gropp et al., GCN Circ. 29158)
with remote telescope T18 (0.32-m f/8.0 reflector + CCD) of
iTelescope.Net in observatory AstroCamp at Nerpio (Spain) on
2020-12-23 since 19:49:22 UT (1 hour 50 minutes 56 seconds after the
trigger). 5 images (with exposures 300, 120 and 180 seconds) were
obtained with Astrodon luminance filter and 4 images (exposures: 300
and 60 seconds) with photometric Johnson V filter. I detected the
optical afterglow in images with position: RA 08:51:09.46 Dec
+71:10:47.00. It is not present in the Pan-STARRS images.

The following magnitudes were measured from comparison to r magnitudes
of nearby stars from Pan-STARRS DR1 catalogue (Chambers et al., 2016):

Time of start (UT)  Exp.time (s.)  Bin.  Mag. r   Mag. error    Filter
19:49:22            300            1     19.2     0.2           Luminance
19:56:25            300            1     19.3     0.4           V
20:26:25            300            2     19.9     0.4           V
20:33:07            300            2     20.1     0.3           Luminance

Magnitudes were not corrected for Galactic extinction.

Stacked image (4x300 + 2x120 + 180 sec.) available here:
Looking for U.S. government information and services? Visit