AstroNote 2026-30

We report optical spectroscopic classification of AT2026bzr (z=0.070), AT2026cqg (z=0.054) and AT2026avc (z=0.086) as Type 1a SNe. All spectra show features of Ca II, Si II, Mg II, Fe II and S II. The spectrum of AT 2026bzr appears to show an older Type 1a SN. Redshifts are estimated from the SN spectra.

We also report optical spectroscopic classification of AT2026fq as an AGN at z=0.055 (as estimated from the Balmer emission lines). Analysis of the collected spectrum reveals an emission peak centered at approximately 7000 Å (corresponding to ~10^14 Hz), a feature often associated with the synchrotron component in Active Galactic Nuclei (AGNs). For comparison purposes, the Spectral Energy Distribution (SED) available in the Firmament AGN database (https://firmamento.nyuad.nyu.edu/data_access) was consulted for coordinates 140.635756667 -16.9854033333. The archive data corroborate the presence of an emission maximum at ~10^14 Hz, evidencing a high flux in this spectral band, which is indicative of the contribution of the host galaxy. We were unable to identify the host galaxy in any publicly available catalogues.

Additionally, spectroscopic observation of AT2026cha showed a blue featureless spectrum. GELATO (Harutyunyan et al. 2008 2008A&A...488..383H) classification returns a match with the early phases of a Type II SN, although classification is unreliable. Therefore, classification of this object is not possible with the current data and we set it as Unknown. AstroNote 2026-29 (https://www.wis-tns.org/astronotes/astronote/2026-29) reports a rapid rise in the transient light curve. Follow-up observations for this object are highly encouraged.

Targets were supplied by ATLAS (Tonry et al. 2018 2018PASP..130f4505T), the Zwicky Transient Facility ZTF (Bellm et al. 2019 2019PASP..131a8002B) with the data stream processed by the ALeRCE broker (Forster et al. 2020 2021AJ....161..242F).

Observations were taken with the EFOSC2 spectrograph, with Grism 11 (3380-7520Å, 16Å resolution) at the ESO New Technology Telescope (NTT) during the nights of 2026 Feb 08 and 09 (UT). The seeing during observations is reported as AT 2026cha (0.696), AT 2026bzr (0.798), AT 2026fq (0.646), AT 2026cqg (0.678), AT 2026avc (0.804). These observations were conducted in the context of the ESO La Silla Observing School 2026. Follow-up observations in both optical and IR wavelengths are highly encouraged.