TITLE: GCN CIRCULAR NUMBER: 32897 SUBJECT: GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits DATE: 22/10/31 02:47:47 GMT FROM: Toktarkhan Komesh at Nazarbayev University toktarkhan.komesh@nu.edu.kz
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 221028A 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 started observations at UT 2022-10-28 13:47:19, 1852 s after the BAT trigger. Observations were made under partially cloudy conditions, beginning with the target at an altitude of 82 deg. No new or changing sources consistent with the XRT position (Lien 2022, GCN 32874) were detected. 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) ------------ -------- ----------- ------ ------ ----- ------ 13:47:19 1852 13:48:19 19.3 18.9 18.7 60 13:48:19 1912 13:58:19 20.3 19.4 20.0 600
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 an image with individual exposure time (first row) and for images co-added to the given exposure time (second row). The given upper limit values are derived from the average calibration with only 2-4 standard stars per co-added frame, and no other analysis or corrections.
---------------------------------- NU = Nazarbayev University, Nur-Sultan, Kazakhstan UCB = University of California, Berkeley, USA FAI = Fesenkov Astrophysical Institute, Kazakhstan
This research has been funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP14870504). 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.