The BHTOM.space network coordinated an observing campaign to monitor the ASASSN-25fd (=Gaia DR3 6059209882617790336, =Nova Cru 2025, =PNV J12312434-5907133) event discovered on November 29, 2025 by John Seach, Grafton, NSW, Australia (more: http://www.cbat.eps.harvard.edu/unconf/followups/J12312434-5907133.html ) and reported on December 19, 2025, by the ASAS-SN network (https://www.astronomy.ohio-state.edu/asassn/transients.html) to be around 15 mag in V/g band and to be a CV candidate. Strader et al. 2026, https://www.astronomerstelegram.org/?read=17579, took a spectrum and classified this event as a classical nova.
Follow-up observations commenced on December 11, 2025, approximately two weeks after initial discovery and are still ongoing. During this period, approximately 240 measurements were obtained using a 14-inch reflector of the ROAD Observatory (Atacama, Chile). Photometric data were taken in U, B, V & I filters and subsequently transformed into Gaia Synthetic Photometry (GaiaSP) for consistency.
The event was also observed by the ATLAS sky survey. There are some archival measurements from DECaPS (Dark Energy Camera Plane Survey) from mid-2016 between 20 and 22 mag in Sloan bands, which would be consistent with a nova progenitor (9-10 mag dimmer than the explosion itself).
The multi-band light curve in BHTOM shows a steady decline in brightness for the entire period of observations, but there is a significant rise in all optical bands measured on February 1, 2026 (~0.8 mag in GaiaSP/I band). Such features have been reported in the past in many novae explosions and may be attributed to different physical mechanisms (see Strope, Schaefer & Henden 2010 for examples).
Observations of the object with BHTOM will continue until it disappears in the background.
Detailed light curves and associated statistics are presented on the webpage: https://bhtom.space/public/targets/ASASSN-25fd .Further details and the full photometric dataset are available for download by registered users of the BHTOM.space 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).
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