AstroNote 2026-52

We report the discovery of a possible Nova found in the Vera C. Rubin Observatory commissioning alert stream via the Babamul broker (du Laz et al., 2026). The transient AT 2026epw (Object ID: LSST-AP-DO-170046106280394867) is located at RA: 185.49089 deg (12h21m57.8s,  J2000) deg and Dec: 8.6600 deg (+08d39m26.0s,  J2000). 

Visual inspection suggests that the transient is 54.2’’ offset from the host galaxy UGC 07424. The host galaxy is at 25.1 Mpc (Kent et al., 2008), and at this distance, the projected separation of the transient from the host nucleus is 6.6 kpc. The photometry acquired during the first detection epochs (around MJD 61094.19) yields absolute magnitudes of M_g = -8.9, M_r = -9.0, and M_i = -9.0. Further, the source shows a fading rate of  0.54 mag/day in r-band, 0.64 mag/day in g-band, and 0.42 mag/day in i-band. The lack of reddening disfavours a kilonova or an afterglow scenario. Given the photometric evolution and absolute magnitude, we suggest this is a classical nova candidate.

Babamul link to the source: https://babamul.caltech.edu/objects/LSST/170046106280394867

The Babamul alerts broker and BOOM software infrastructure (du Laz et al. 2026) is co-developed by the California Institute of Technology and the University of Minnesota. This work acknowledges support from the National Science Foundation through AST Award No. 2432476 (PI Kasliwal; co-PI Coughlin) and leverages experience from the Zwicky Transient Facility (co-PIs Graham and Kasliwal).