AstroNote 2026-80

The BHTOM.space global network of telescopes carried out a coordinated observing campaign to monitor several LSST targets. Photometric data were obtained across multiple optical filters and subsequently transformed into Gaia Synthetic Photometry (GaiaSP) to ensure consistency. Here, we present observations of three events. Details on the telescopes involved, as well as the specific photometric bands used, are available on the corresponding BHTOM.space object pages listed below.

AT 2026ejx, was discovered by Vasylyev et al. 2026 (2026TNSTR.818....1V), and flagged as a possible SN by the LASAIR broker (https://lasair.lsst.ac.uk/objects/170046089928376424/) and as a possible AGN by the ALERCE broker (https://lsst.alerce.online/object/170046089928376424?survey=lsst&page=1&page_size=20&count=false&selected_oid=170046089928376424). We note that this transient is now declining in the bluer bands (B, V and g). We encourage the community to obtain classification spectra to help disentangle the differing broker associations. Detailed light curves and associated statistics are presented on the webpage: http://bhtom.space/public/targets/LSST_170046089928376424.

SN 2026eqf was discovered by Peloton et al. 2026 (https://www.wis-tns.org/object/2026eqf/discovery-cert), it was flagged as an event with a Potential Pre-Peak by Brennan et al. 2026 (2026TNSAN..55....1B) and classified as a SN IIn by Chen et al. 2026 (2026TNSAN..62....1C). This event continues its steady rise, see detailed light curves and associated statistics on the webpage: http://bhtom.space/public/targets/LSST_313994139532263447.

SN 2026ekf was discovered by Vasylyev et al. 2026 (2026TNSTR.817....1V), photometrically flagged as a SN Ia (de Soto et al. 2026, 2026TNSAN..50....1S) or a TDE/SLSN/glSNIa (Umuzigazuba et al. 2026, 2026TNSAN..67....1U) and spectroscopically classified as a SN Ia by Franz et al. 2026 (2026TNSCR1099....1F). This supernova is currently near peak brightness, with multiple bumps visible around maximum light. The significance of these features remains unclear, particularly in the context of the multi-wavelength light curve obtained with different facilities, which also include alert photometry from the Zwicky Transient Facility (ZTF; Bellm et al. 2019; Graham et al. 2019). See detailed light curves and associated statistics on the webpage: http://bhtom.space/public/targets/LSST_170032917163016282.

BHTOM.space will continue monitoring these and other LSST targets. Additional photometric follow-up can be requested by users of the platform.

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).