TITLE:   GCN CIRCULAR
NUMBER:  38055
SUBJECT: GRB 241030A: Swift-UVOT observations of the optical prompt flare
DATE:    24/11/03 09:57:36 GMT
FROM:    Hao Zhou at Purple Mountain Observatory, CAS <haozhou@pmo.ac.cn>

Q. L. Wang, Y. Wang, H. Wang, H. Zhou, Z. P. Jin, Y. Z. Fan (PMO) reports:

Swift-UVOT began to observe the field of GRB 241030A about 83 seconds after the trigger in the event mode (Klingler et al. GCN [37956](https://gcn.nasa.gov/circulars/37956), Breeveld et al. GCN [37974](https://gcn.nasa.gov/circulars/37974)).

Similar to [Jin+2023](https://ui.adsabs.harvard.edu/abs/2023NatAs...7.1108J/abstract) and [Zhou+2023](https://ui.adsabs.harvard.edu/abs/2023ApJS..268...65Z/abstract), we construct white-band and U-band light curves with the time bin of 20 seconds, and the light curves clearly show two bumps peak around 135s and 405s.

The behavior of the first bump is similar to that of X-ray and Gamma-ray light curves, which implies the first bump seems to orginate from the prompt flare, and the second one could be the onset of the afterglow.

The multi-band light curve is avaliable at [https://postimg.cc/BX25wrFn](https://postimg.cc/BX25wrFn).