SIMBAD references

In this work we present the photometric and spectroscopic observations of type IIb supernova 2017gpn. This supernova was discovered in the error-box of the LIGO/Virgo G299232 gravitational-wave event. We obtained the light curves in the B and R passbands and modelled them numerically using the one-dimensional radiation hydrocode STELLA. The best-fitting model has the following parameters: the pre-SN star mass and the radius are M ≃ 3.5 M_☉ and R ≃ 50 R_☉, respectively; the explosion energy is E_ exp_ ~1.2×10⁵¹ erg; the mass of radioactive nickel is M_ ^56Ni ~0.11 M_☉, which is completely mixed throughout the ejecta; and the mass of the hydrogen envelope M_ H_env_ ≃ 0.06 M_☉. Moreover, SN 2017gpn is a confirmed SN IIb that is located at the farthest distance from the centre of its host galaxy NGC 1343 (i.e. the projected distance is ∼21 kpc). This challenges the scenario of the origin of type IIb supernovae from massive stars.