ATLAS and ZTF optical observations of the X-ray transient AT2019wey during the recent X-ray rebrightening
ATel #17686; Albert K. H. Kong (NTHU)
on 17 Feb 2026; 14:35 UT
Credential Certification: Albert Kong (akong@phys.nthu.edu.tw)
Subjects: Optical, X-ray, Binary, Black Hole, Transient
Following the recent report of the X-ray rebrightening of the Galactic X-ray transient AT2019wey (ATel #17680), we searched for the ATLAS database to investigate the optical variability. Using the ATLAS forced photometry server (https://fallingstar-data.com/forcedphot/), we extracted the long-term optical light curve of AT2019wey. Based on the forced measurement on the target images, the o-band magnitude of AT2019wey decreased from 17.1 mag in 2025 March to 18.1 mag in 2025 late-December. Since then, AT2019wey has gradually rebrigtened to a magnitude of 17.4 in early February. Furthermore, we checked the ZTF database via the ALeRCE ZTF explorer, and the source shows similar behaviour (https://alerce.online/object/ZTF19acwrvzk).
We also examined the MAXI X-ray light curve of AT2019wey. The source has shown an X-ray softening trend with a clear brightening in the 2-4 keV band since 2025 late-December. This is consistent with the SVOM/ECLAIRs and optical observations.
Multi-wavelength follow-up observations are encouraged to monitor the source's variability.
ATLAS lightcurve of AT2019wey
