2025ApJ...987..129W

We present a detailed analysis of the long-duration GRB 241030A detected by Swift. Thanks to the rapid response of the X-Ray Telescope (XRT) and Ultraviolet/Optical Telescope, the strongest part of the prompt emission of GRB 241030A has been well measured simultaneously from the optical to hard X-ray bands. The time-resolved WHITE band emission shows strong variability, largely tracing the activity of the prompt γ-ray emission, suggesting that it may also be produced by internal shocks too. The joint analysis of the XRT and Burst Alert Telescope data reveals the presence of a thermal component with a temperature of a few keV, which can be interpreted as the photosphere radiation, and the upper limit of the Lorentz factor of this region is found to range between approximately 20 and 80. The time-resolved analysis of the initial U-band exposure data yields a very rapid rise (∼t^5.3) with a bright peak reaching 13.6 AB magnitude around 410 s, which is most likely attributed to the onset of the external shock emission. The richness and fineness of early observational data have made this burst unique for studying various radiation mechanisms of γ-ray bursts.