AstroNote 2026-130

We report on the multi-band photometric monitoring campaign of 7 variable sources, conducted through the BHTOM network.

AT 2026coj was first discovered by XOSS on February 8, 2026 (Xu et al. 2026) and a blue continuum with broad Balmer lines in absorption in optical spectra classified this source as a Cataclysmic Variable (Ochner et al. 2026). The decline phase of the CV outburst has been monitored by the BHTOM network in griBVRI bands. Detailed light curves and associated statistics of AT 2026coj are presented on the webpage: https://bhtom.space/public/targets/AT2026coj.

AT 2025wygwas discovered by Tadashi Kojimaon September 5, 2025, with a Canon EOS 6D digital camera. Optical spectrum from Lesedi/Mookodi classified this as a classical nova of the Fe II spectroscopic type (Mlangeni et al. 2025). AT 2025wyg was extensively followed up by the BHTOM network in BVI optical bands by the ROAD Observatory C14 Telescope (Chile). Detailed light curves and associated statistics of AT 2025wyg are presented on the webpage: https://bhtom.space/public/targets/AT2025wyg.

AT 2019uixwas first discovered by Gaia through GaiaAlerts in the Gaia-G band on November 6, 2019 (Hodgkin et al. 2019). It is a Young Stellar Object (YSO) candidate. The light curve clearly shows eruptive behavior in VGIRB bands through the BHTOM network. Detailed light curves and associated statistics of  AT 2019uixare presented on the webpage: https://bhtom.space/public/targets/Gaia19eyy.

AT 2024sfnis a candidate microlensing event and was first discovered by Gaia through GaiaAlerts in the Gaia-G band on August 3, 2024 (Hodgkin et al. 2024). The decline part of  AT 2024sfn has been extensively followed in the gri bands through the BHTOM network. Detailed light curves and associated statistics of  AT 2024sfn are presented on the webpage: https://bhtom.space/public/targets/Gaia24cfg.

 AT 2024aboowas reported by GaiaAlerts on November 11, 2024 (Hodgkin et al. 2024), and it is the famous YSO V899 Mon, a FUor/EXor intermediate case. The dramatic behavior of V899 Mon has been extensively monitored by BHTOM network in the griBVIU bands and observations are still going on. Detailed light curves and associated statistics of AT 2024aboo are presented on the webpage: https://bhtom.space/public/targets/Gaia24dhn.

AT 2024abwuwas first discovered by Gaia through GaiaAlerts in the Gaia-G band on November 17, 2024 (Hodgkin et al. 2024). This target has been monitored by the BHTOM network in the grizBVRIU bands. It can be a Be star. Detailed light curves and associated statistics of AT 2024abwu are presented on the webpage: https://bhtom.space/public/targets/Gaia24dja.

AT 2025ahnwas first discovered by ATLAS (c-band) on January 26, 2025 (Tonry et al. 2025). BHTOM network started monitoring from January 29, 2025 and the rapid decline phase was mainly monitored in the V band. There is a faint blue object at this location in the Legacy Survey and PanSTARRS images and the rapid decline in the V band light curve makes it a candidate for a Cataclysmic Variable or Dwarf Nova. Detailed light curves and associated statistics of AT 2025ahn are presented on the webpage: https://bhtom.space/public/targets/AT2025ahn. 

The targets are observed by the LCO Network, 51-cm Slooh Australia Telescope (Australia), 1.2-meter Kryoneri Observatory (Greece), 50-cm University of Zielona Góra Observatory (Chile), 40-cm ROAD Observatory (Chile), 0.6-m Cassegrain Zeiss telescope Mt. Suhora Observatory (Poland), 30-cm SUTO-Otivar Telescope (Spain), 41-cm School Astronomical Observatory Bolecina (Poland), 40-cm E-Eye Telescope (Spain), 90-cm Telescope of Nicolaus Copernicus University (Poland), 0.8-m Moletai Observatory Telescope (Lithuania), 1.23-m CAHA Telescope (Spain), 20-cm Znith Astronomy Observatory (Malta), 25-cm Adonis Observatory Telescope (Belgium) and 40-cm GoChile-GoT1 Telescope (Chile). Photometric observations were transformed into Gaia Synthetic Photometry (GaiaSP) for consistency.

Data accessed through the BHTOM networkis subject to its Terms and Conditions available here. Public links to the light curves are provided here in the spirit of open science and collaborative research; full downloads are available to registered users upon creating a free account at BHTOM.

We share these resources because we believe in free data accessibility and the value of broad scientific collaboration. In return, we kindly ask that researchers who find these light curves useful to properly acknowledge the BHTOM project. Proper credit is essential to sustaining the collaborative spirit that makes this data possible.

Researchers planning to use these data are warmly encouraged to reach out to the BHTOM team in advance at contact@bhtom.space.

Acknowledgements: BHTOM.space is based on the open-source TOM Toolkit by LCO and has been supported by the European Union's research and innovation programmes under grant agreements No 101004719 (OPTICON-RadioNet Pilot, ORP) and 101131928 (ACME).