IceCube-230217A: BOOTES-4/MET Optical Observations

On 2023-02-17 at 20:49:43.4 UT (T0) IceCube detected a track-like event with a moderate probability of being of astrophysical origin. Two gamma-ray sources (4FGL J0816.9+2050 and 4FGL J0817.1+1955) listed in the 4FGL-DR3 Fermi-LAT catalog are located within the 90% error region of the candidate neutrino event (GCN 33337). We observed the two gamma-ray sources and the best-fit position of IceCube-230217A with BOOTES-4/MET 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 not for the gamma-ray source 4FGL J0817.1+1955. 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| 0.797 | 23-02-18 15:57:25.28 | 19.96 (0.11) | 2*350s (co-added) | Clear J0817.1+1955 | 0.725 | 23-02-18 14:14:38.47 | 19.44 (0.07) | 350s | Clear ------------------------------------------------------------------------------------------------------------- 0.674 days after T0, the magnitude value of 4FGL J0816.9+2050 in SDSS-r band is 18.055+/-0.17 (without being corrected for Galactic extinction). Compared with the magnitude value of SDSS-DR16, the target is not brightening during our observation period. ------------------------------------------------------------------------------------------------------------- The Burst Optical Observer and Transient Exploring System (BOOTES, bootes.iaa.es) is a completed world-wide network of robotic telescopes led at IAA-CSIC (Spain) which aims at following-up transients and other astrophysical sources in the sky for which the first station was installed in 1998 (Castro-Tirado et al. 1999). The fourth station of the BOOTES Network, BOOTES-4/MET, is located at the Lijiang Observatory of the Yunnan Observatories of China (Xiong et al. 2020). See also Hu et al. (2021). We acknowledge the support of BOOTES-4 technical staffs.