Identification and spectroscopic classification of a reddened classical nova AT2026ldc with strong CO emission

ATel #17804; Viraj Karambelkar (Columbia University), Danielle Frostig (CfA), Kishalay De (Columbia), Tanishk Mohan (IIT Bombay) and the WINTER collaboration.
on 15 May 2026; 18:04 UT
Credential Certification: Viraj Karambelkar (vk2588@columbia.edu)

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We report the identification and spectroscopic observations of a bright optical and near-IR (NIR) transient found in the regular survey operations of the the Zwicky Transient Facility (ZTF, Bellm et al. 2018) and followed up with the Wide-field Infrared Transient Explorer (WINTER, Lourie et al. 2020, Frostig et al. 2024). The source has also been independently discovered and reported to the Transient Name Server by the DCAP Team with ZTF data as AT2026ldc / ZTF26aaunaud.

We flagged this source, ZTF26aaunaud, in a dedicated search for large amplitude Galactic outbursts in ZTF data, with magnitudes of r=16.7+/- 0.02 , i=13.8 +/- 0.01, and g > 20.2 mag on UT 2026-05-12. We subsequently obtained J-band observations with the WINTER telescope on UT 2026-05-12. The source was detected with a J-band magnitude of 11.2 +/- 0.1 (AB), and assigned the name WNTR26bjnyb. The coordinates of the source are RA = 18:29:31.90 Dec = -10:55:31.26

We obtained a NIR spectrum of this source with the SpeX spectrograph on the NASA Infrared Telescope Facility (IRTF) on UT 2025-05-12. Our spectrum shows strong, broad (>500 km/s) emission lines, including of H, He, C, O, with the He lines exhibiting P-cygni profiles, resembling those seen in classical novae.

We also detect strong CO emission bands, similar to that seen in the Nova Ophiuchus 2017 (Vishal et al. 2017).

Further observations are encouraged.