MAXI/GSC detection of an X-ray flare from HR 1099 on 2025-03-21 UT
ATel #17096; N. Nagashima, Y. Tsuboi (Chuo U.), H. Negoro, M. Nakajima, Y. Kudo, H. Shibui, K. Takagi, H. Takahashi, K. Tatano, H. Nishio (Nihon U.), T. Mihara, T. Kawamuro, S. Yamada, S. Wang, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, Y. Kawakubo, H. Hiramatsu, H. Nishikawa, Y. Kondo, S. Sasao, A. Yoshida (AGU), H. Sugai (Chuo U.), M. Shidatsu, Y. Niida (Ehime U.), I. Takahashi, M. Niwano, N. Higuchi, Y. Yatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, Y. Okada, K. Fujiwara (Kyoto U.), M. Yamauchi, Y. Otsuki, T. Hasegawa, M. Nishio (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.) report on behalf of the MAXI team:
on 21 Mar 2025; 11:16 UT
Credential Certification: Yohko Tsuboi (tsuboi@phys.chuo-u.ac.jp)
Subjects: X-ray, Binary, Star, Transient, Variables
Referred to by ATel #: 17098
At 12:47 on 2025-03-21 UT, the MAXI/GSC nova alert system triggered on a bright source at a position consistent with that of an RS CVn star HR 1099 (V711 Tau).
The position is determined from the data at the triggered scan, as (R.A., Dec) = (54.244 deg, 0.616 deg) = (03 36 58, +00 36 57) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.73 deg and 0.51 deg, respectively. The roll angle of long axis from the north direction is 133.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
This position is consistent with that of an RS CVn star HR 1099. No other source is listed in the ROSAT Bright Source Catalog in this error region.
The X-ray flux averaged over the scan was 34 +- 16 mCrab (4.0-10.0 keV, 1 sigma error) at the triggered scan, corresponding to a luminosity of 7 × 1031 erg s-1 s -1 for an assumed distance of 30 pc.
The flare e-folding time was 0.31 days. The total energy released during the flare is 2 × 10 36 erg.
