IceCube-230122A: BOOTES-2/TELMA Optical Upper Limit

On 2023-01-22 03:50:02.00 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The nearest one is 4FGL J0100.3+0745 within the 90% uncertainty region of the event, 1.68 deg away from the best-fit event position (GCN 33204, 33212). We observed the BL Lac object 4FGL J0100.3+0745 and the best-fit position of IceCube-230122A with BOOTES-2/TELMA robotic telescope.The magnitudes were calculated using bright stars in the same frame and the SDSS DR16 catalogue as reference. We did not detect any optical source within the best-fit position, and also the optical counterpart of the 4FGL J0100.3+0745. The upper limits of magnitudes (without being corrected for Galactic extinction) are given as follows. Sources | Tmid-T0 (day) | UT (start) | Upper Limit (error) | Exposure Time | Filter -------------------------------------------------------------------------------------------------------------- Best-fit position | 0.764 | 23-01-22 22:10:44.8 | 18.79 (0.22) | 2*300s (co-added) | Clear 4FGL J0100.3+0745 | 0.699 | 23-01-22 20:36:22.3 | 19.51 (0.03) | 8*300s (co-added) | Clear --------------------------------------------------------------------------------------------------------------- The Burst Optical Observer and Transient Exploring System (BOOTES) is a world-wide automatic telescope network which aims to repaid follow-up of transient and astrophysical sources in the sky for which the first station was installed in 1998 (Hu et al. 2021). The BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain). We acknowledge the support of these staffs from the BOOTES telescope networks.