EP-WXT trigger 01709258989 — All Circulars

WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and

Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team:


The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at

Lick Observatory, automatically responded to the EP-WXT trigger

01709258989 (Zhou et al. GCN 44054) starting at 04:57 UT, about 2.4

hours after the trigger. A set of clear (roughly R) filter images

were obtained and lasted for ~2.5 hours. Photometry on the suggested

flare star 1RXS J073101.9+460030 (confirmed by Perez-Garcia

et al., GCN 44056) show that its brightness remain around 12.5 mag

for about 1 hour, then another flare started at 06:05 UT (3.53 hours

after trigger), brightened to ~12.0 mag at peak time of 06:11 UT, then

decreased to ~12.4 mag around 06:23 UT. This confirming the EP X-ray

trigger is related to the stellar flare.

I. Perez-Garcia, S.-Y. Wu, A. J. Castro-Tirado, E. J. Fernandez-Garcia, M.D. Caballero-Garcia, S. Guziy,  G. Garcia-Segura, R. Sanchez-Ramirez (IAA-CSIC),  Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), L. Hernandez-Garcia (Univ. de Valparaiso), M. Gritsevich (Univ. of Helsinki), D.-R. Xiong (Yunnan Observatories of CAS), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), on behalf of a larger collaboration, report:

Following the detection of EP-WXT trigger 01709258989 (Zhou et al. GCN 44054), the 0.6m BOOTES-7 robotic telescope at San Pedro de Atacama (Chile) responded to the alert on Mar. 20, 02:39 UT (i.e. 6-min after trigger, 1 min after notification). Within the reported EP-FXT error circle we find the star 1RXS J073101.9+460030 decreasing 0.9, 0.5 and 0.4 mag in g, r and i filters during a 20 min time interval, confirming EP-WXT trigger 01709258989 as due to a stellar flare.

We thank the staff at San Pedro de Atacama Celestial Observations for their excellent support.