AstroNote 2023-267

AT 2023uhx was discovered by K. Itagaki on UTC 2023-10-07 20:54:08 in the nearby galaxy NGC 3893. Given the host distance of ~16.40 Mpc and a distance modulus of 31.08 mag (Tully et al. 2016), the transient's absolute magnitude in the Clear band is of M=-13.88 mag, which is in the expected range for LRNe (e.g. between -6 and -16 mag). On the night of 10th of October 2023 (MJD 60228.204) we obtained a classification spectrum (Program: 23B-2.2-017, PI: N. Blagorodnova, Observers: M. Blazek, S. N. Molina) with the low-resolution spectrograph CAFOS (Calar Alto Faint Object Spectrograph), mounted on the CAHA 2.2m telescope. The used grism G-200 offers a resolution of 400 - 500 km/s. The data was reduced using a custom-developed Python pipeline.

The spectrum shows common characteristics with other LRNe at early times: a blue continuum (black body fit of ~9300K in the 5000-9000A region), strong Balmer emission lines, and narrow Fe II lines. We also detect unresolved absorption from the Na I doublet. The H alpha shows a good fit to a Lorentzian profile with FWHM=930+/-20 km/s, and a center of 6579 A (once corrected for the host redshift of z=0.003226), which is ~2157 km/s redshifted from its expected rest wavelength.

We have requested multi-band follow-up photometry with the 0.8m Telescope Joan Oró (TJO).  Additional follow-up is encouraged.

Based on observations collected at the Centro Astronómico Hispano en Andalucía (CAHA) at Calar Alto, operated jointly by Junta de Andalucía and Consejo Superior de Investigaciones Científicas (IAA-CSIC).