MAXI/GSC detection of an X-ray flare from EV Lac on 2025-09-09 UT
ATel #17381; N. Nagashima, Y Ishihara, Y. Tsuboi (Chuo U.), M. Nakajima (Nihon U.), T. Mihara (RIKEN), H. Negoro (Nihon U.), K. Takagi, H. Takahashi, H. Nishio (Nihon U.), T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, Y. Kawakubo, H. Hiramatsu, Y. Kondo, A. Yoshida (AGU), H. Sugai (Chuo U.), M. Shidatsu, C. Kang, T. Nakamoto (Ehime U.), I. Takahashi, Y. Yatsu (Science Tokyo), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, K. Fujiwara (Kyoto U.), M. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), T. Kawamuro (Osaka U.), S. Yamada (Tohoku U), report on behalf of the MAXI team:
on 10 Sep 2025; 04:16 UT
Credential Certification: Yohko Tsuboi (tsuboi@phys.chuo-u.ac.jp)
Subjects: X-ray, Star, Transient, Variables
At 21:41 on 2025-09-09 UT, the MAXI/GSC nova alert system triggered on a source at a position consistent with that of the dMe star EV Lac.
The position of the X-ray enhancement is (R.A., Dec) = (340.998 deg, 43.846 deg) = (22 43 59, +43 50 46) (J2000)
with a 90% C.L. statistical error of 0.32 deg and an additional systematic uncertainty of 0.1 deg (90% containment radius).
The position was determined with the data obtained at a scan transits
from 21:41 on 2025-09-09 UT.
This position is consistent with that of EV Lac.
The current maximum flux is 4 × 10-9 erg s-1 cm-2 (2-20 keV). The corresponding luminosity is 1 × 1031 erg s-1 for an assumed distance of 5 pc.
This is the second time that MAXI has detected an X-ray flare from EV Lac since 2010-06-11 UT.
