TITLE: GCN CIRCULAR NUMBER: 38777 SUBJECT: GRB 250101A NUTTelA-TAO / BSTI Early Measurements DATE: 25/01/02 12:04:47 GMT FROM: Toktarkhan Komesh at Nazarbayev University toktarkhan.komesh@nu.edu.kz
T. Komesh (NU), Z. Abdullayev (NU), Z. Maksut (NU), B. Grossan (UCB, NU), D. Berdikhan (NU), M. Krugov (FAI) and E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory:
The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) pointed at GRB 250101A on receipt of an automated GCN / BAT position alert, observing in Sloan g' and r' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).
We started observations at 13:24:00 UT on 2025-01-01, 70 s after the BAT trigger. Observations were made in partly cloudy conditions. A new and changing source consistent with the XRT position (M.R. Goad et al., GCN 38761) was detected. Note that these observations provide essentially full-time coverage, simultaneous in two bands. We report the following photometric values for the optical transient:
tc-t0(s) g'(mag) err r'(mag) err exposure_time (s) -------------------------------------------------------------- 100 18.66 0.07 18.20 0.07 57 166 17.64 0.12 17.24 0.12 15 181 17.51 0.10 16.98 0.14 15 196 17.11 0.09 16.87 0.12 15 211 17.34 0.13 16.90 0.09 15 226 17.37 0.12 16.77 0.12 15 241 17.31 0.09 16.65 0.06 15 256 17.30 0.11 16.79 0.06 15 271 17.43 0.09 16.85 0.10 15 286 17.37 0.11 16.89 0.08 15 301 17.50 0.16 17.02 0.08 15 316 17.68 0.20 17.01 0.08 15 331 17.52 0.15 17.01 0.10 15 346 17.67 0.11 17.08 0.09 15 361 17.60 0.11 17.13 0.09 15 376 17.62 0.15 16.95 0.13 15 391 17.96 0.14 16.91 0.08 15 406 17.61 0.15 17.39 0.13 15 421 17.81 0.13 17.23 0.12 15 436 17.46 0.13 17.41 0.12 15 451 18.10 0.15 17.41 0.11 15 466 17.78 0.17 17.30 0.11 15 481 17.81 0.13 17.29 0.10 15 496 17.70 0.15 17.36 0.15 15 511 17.92 0.13 17.45 0.11 15 526 17.68 0.12 17.46 0.12 15 541 18.30 0.19 17.53 0.13 15 556 17.86 0.18 17.34 0.13 15 571 17.96 0.14 17.31 0.14 15 586 17.66 0.16 17.43 0.11 15 601 18.16 0.17 17.82 0.14 15 616 17.90 0.15 17.72 0.16 15 631 17.85 0.13 17.23 0.11 15 653 18.12 0.12 17.58 0.10 30 683 18.06 0.10 17.47 0.07 30 713 18.05 0.10 17.54 0.09 30 743 18.01 0.10 17.46 0.08 30 864 18.20 0.05 17.54 0.04 60 924 18.17 0.07 17.67 0.06 60 984 18.21 0.06 17.67 0.04 60 1044 18.26 0.06 17.77 0.04 60 1104 18.37 0.07 17.81 0.05 60 1164 18.33 0.06 17.81 0.05 60 1224 18.46 0.07 17.82 0.05 60 1284 18.48 0.07 17.91 0.05 60 1344 18.56 0.07 17.84 0.05 60 1404 18.43 0.06 18.04 0.05 60 1464 18.43 0.07 18.15 0.06 60 1524 18.63 0.07 18.12 0.06 60 1584 18.66 0.08 18.19 0.07 60 1644 18.73 0.08 18.26 0.07 60 1704 18.70 0.08 18.18 0.06 60 1764 18.66 0.08 18.23 0.06 60 1824 18.81 0.08 18.38 0.08 60 1884 18.82 0.08 18.39 0.07 60 1944 19.01 0.10 18.27 0.07 60 2004 18.83 0.10 18.43 0.08 60 2064 18.87 0.09 18.33 0.07 60 2124 18.75 0.08 18.34 0.07 60 2184 18.99 0.10 18.46 0.08 60 2244 18.97 0.10 18.49 0.08 60 2304 18.90 0.09 18.48 0.09 60 2364 19.21 0.12 18.45 0.08 60 2424 19.01 0.10 18.43 0.07 60 2484 18.95 0.10 18.64 0.09 60 2544 19.10 0.10 18.64 0.09 60 2604 18.98 0.10 18.77 0.10 60 2664 19.12 0.11 18.76 0.10 60 2724 18.93 0.10 18.78 0.10 60 2784 19.23 0.12 18.85 0.11 60 2844 19.18 0.12 18.78 0.11 60 2904 19.43 0.15 18.59 0.09 60 2964 19.15 0.12 18.92 0.12 60 3024 19.23 0.13 18.72 0.11 60 3084 19.19 0.13 18.65 0.11 60 3144 19.30 0.15 18.87 0.13 60 3204 19.18 0.13 19.07 0.16 60 3294 19.42 0.13 18.86 0.10 120 3414 19.38 0.13 18.70 0.09 120 3534 19.41 0.08 19.05 0.14 120 3654 19.38 0.15 18.96 0.14 120 3774 19.37 0.17 19.00 0.16 120 4166 19.65 0.11 18.89 0.08 360 4526 19.82 0.19 19.17 0.13 360
tc-t0 = trigger time minus image center time. Calibration was done with 5 bright Pan-STARRS catalog stars on our images. A light curve of the optical transient is presented in Figure 1: https://ecl.nu.edu.kz/research/observations/gamma-ray-bursts/grb250101a
Our results are in agreement with those reported in previously published circulars (Li et al., GCN 38753; Mohan et al., GCN 38754; Wu et al., GCN 38758; Escudero-Coca et al., GCN 38769; Zhang et al., 38744).
We caution the reader that these are preliminary results, without color or other corrections, and will likely change in small measure. Please also note that times are approximate.
---------------------------------- NU = Nazarbayev University, Astana, 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. AP26103591). 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.
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