AstroNote 2023-28

SN 2023awp was discovered on Jan. 27th with an apparent magnitude of 19.58 in the g band (Transient Name Server, https://www.wis-tns.org/object/2023awp/discovery-cert) and classified as Type IIn (https://www.wis-tns.org/object/2023awp/classification-cert) by the Zwicky Transient Facility (ZTF).

In the framework of the Nordic-optical-telescope Un-biased Transient Survey 2 (NUTS2), we obtained a spectrum of SN 2023awp with the Nordic Optical Telescope (+ALFOSC) on Feb. 9.45UT (range 360-960 nm, resolution 2nm). The spectrum reveals a red continuum with narrow H-Balmer emission, as well as features associated with He I 5876, He I 6678, and He I 7065.

There is no evidence of broad features nor in emission or in absorption. An intense Na I D absorption suggests high extinction in the host galaxy. We measure an EW > 3.3A, which translates to E(B-V)>0.5 mag (Turatto et al. 2003). Even after reddening correction, the continuum remains red, indicating an advanced stage in the evolution. This is in agreement with the first detection, reported on Jan. 27th.

From the narrow emission, we measure a redshift z=0.0128. Accounting for the reddening and the last apparent magnitude reported by ZTF (r=17.27), this gives an r-band absolute magnitude of -18.1 +/- 0.2 (r band) on Feb. 2.

Overall, the spectrum is very similar to that of type IIn-P SNe (e.g. SN2011ht-like, Mauerhan et al. 2013), although the absolute magnitude in this case is brighter.