The topic of the September expedition to Namibia - Galaxy NGC 1097 with the supernova SN 2023rve.

To travel to the other side of the world, rent a Dobsonian telescope, and stumble upon a galaxy where a supernova has exploded is quite a gift from fate or a cosmic coincidence

NGC 1097 (Caldwell 67) is a barred spiral galaxy located in the constellation Fornax. It is visible from southern Poland (Kraków) at a maximum of 10 degrees above the horizon, making it practically inaccessible. It was discovered by the British astronomer John Herschel on October 9, 1790.

This is a Seyfert-type spiral galaxy, characterized by a prominent bar running through its central region. NGC 1097 indeed hosts a supermassive black hole at its center, with a mass 140 million times that of the Sun. Surrounding the central black hole is a luminous ring of gas and dust, which is a region of star formation. The spiral arms of the galaxy extend tens of thousands of light-years beyond the ring.

Galaxy NGC 1097 is something of an astronomical treasure trove - it is a well-liked and frequently studied object for various reasons.

It serves as an excellent model for studying gravitational interactions - the presence of the companion galaxy NGC 1097A has a significant impact on NGC 1097, causing visible distortions in its structure. The black hole in this galaxy has been observed in great detail in X-ray and gamma-ray emissions. It is a source of intense electromagnetic radiation, and its dynamics and evolution are subjects of study. Finally, due to its size and activity, NGC 1097 is a home for supernovae, with four observed there - SN 1992bd (Type II, magnitude 15), SN 1999eu (Type II-pec, magnitude 19.7), SN 2003B (Type II, magnitude 17.6), and SN 2023rve (Type II, magnitude 14). As if that wasn't enough, long-exposure visible light photographs reveal four narrow streams of matter seeming to emanate from the core. These have been interpreted as remnants of a tidally disrupted dwarf galaxy.

Finally, a few words about the photograph and the spectrum collected.

We gathered the material at the Hakos astrofarm in Namibia, together with Mateusz Kalisz. During the last night of our expedition, a few, but obstructive clouds rolled across the sky, unfortunately preventing a longer exposure of this object, and it was no longer possible to collect the spectrum of the supernova. Fortunately, we were assisted by Grzegorz Duszanowicz, whom we met personally and who is well-known in our community. He was servicing his telescopes at Hakos and kindly promised to collect the data on his telescope at a later time. Thank you, Grzegorz!

The registered supernova is the fourth in my collection and the third for which we managed to collect the spectrum. It is a Type II supernova - one that formed after the explosion of a star with a mass greater than 9 solar masses. With excellent data from Grzegorz, we managed to capture clear lines of hydrogen and calcium, along with the characteristic spectrum.