XRISM/Xtend Transient Search (XTS) detected an X-ray flare from a YSO

XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1712-2310 on 2025-04-05 TT. The source position is determined to be (R.A., Dec.) = (258.042, -23.162), with a systematic error of ? 40 arcsec. A plausible counterpart is a YSO CD-23 13197, whose distance is 115 pc. CD-23 13197 is located ? 20 arcsec apart from the position of XRISM J1712-2310. The flare started at 2025-04-05 at ? 23:50 TT. The flare reached its peak on 2025-04-06 at ? 01:10. The flare was still ongoing at the end of the XRISM observation, but the e-folding time is estimated to be ? 20 ks. The peak flux is estimated as 1 × 10-12 erg s-1 cm-2 (0.4 – 10.0 keV). Corresponding luminosity is 2 × D120pc × 1030 erg s-1 by assuming the distance to XRISM J1712-2310 of D120pc. We derived the above systematic error for the flux by comparing our derived values for the sources detected with XTS in several observations with those for the corresponding X-ray counterparts. We estimated the systematic error for the source position from the separations between the detected sources with the corresponding counterparts in the same field of view.