GCN Circular 32381

T. Komesh (NU), B. Grossan (UCB, NU), Z. Maksut (NU), M. Krugov (FAI), 
report on behalf of the Energetic Cosmos Laboratory: The Nazarbayev 
University Transient Telescope at Assy-Turgen Astrophysical Observatory 
(NUTTelA-TAO) observed the field of GRB 220711B on receipt of an 
automated GCN / BAT position alert, observing in Sloan g', r' and i' 
bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, 
Kumar & Smoot 2019, JHEA, 32, 14). We received the alert at UT 
2022-07-11 18:16:50, 22 seconds after ��the BAT trigger time, and started 
observations at UT 18:17:02, 12 s after receipt, 34 s after the BAT 
trigger. Observations were made under partially cloudy conditions. No 
new or changing sources consistent with the XRT position (Beardmore 
2022, GCN 32370
Not found
 
 
) were detected. The observations fully cover the 
UVOT/XRT observation time interval and partly cover the prompt emission 
time (D'Ai 2022, GCN 32366
Not found
 
 
). Note that these observations provide 
essentially full-time coverage, simultaneous in all three bands. We 
report the following results: start time t-t0(s) end time UL g' UL r' 
ULi' exposure_time (s) ------------ -------- ----------- ------ ------ 
----- ------ 18:17:02 34 18:18:02 18.3 18.1 17.7 60 18:18:17 109 
18:23:17 19.2 18.9 18.7 300 start time is in UT. t-t0(s) gives the time 
since trigger, in seconds. UL gives the 5 sigma upper limit sensitivity 
in magnitudes, for images co-added to the given exposure time. The first 
row in the table corresponds to co-adds of an initial short exposure 
image sequence of 0.3 s (these sub-second exposures are read-noise 
suppressed by our EMCCD cameras, with high gain electron multiplication 
active; other images are taken in conventional CCD operation mode) for 
g' and r', and 7.5 s for i'. The second row corresponds to co-adds from 
a continuing series of 3 s exposures for g' and r', and 15 s exposures 
for i'.�� Calibration was done with 4 bright Pan-STARRS catalog stars on 
our images. We caution the reader that these are preliminary results, 
without color or other corrections. Please also note that times are 
approximate. ---------------------------------- NU = Nazarbayev 
University, Nur-Sultan, Kazakhstan UCB = University of California, 
Berkeley, USA HKUST = Hong Kong University of Science and Technology FAI 
= Fesenkov Astrophysical Institute, Kazakhstan The NUTTelA-TAO Team 
acknowledges the support of the staff of the Assy-Turgen Astrophysical 
Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical 
Institute, Almaty, Kazkhstan.