After 3 years of trying, I managed to bring home this very faint nebula in the constellation Cassiopeia, a supernova remnant cataloged as CTB1 (Caltech Observatory list B catalogue of radio sources). When discovered in 1955, CTB1 was thought to be a planetary nebula, so Abell included it in his catalog of planetary nebulae as Abell 85. Further research in 1971 showed that CTB1 is, instead, a supernova remnant 10000 light-years away from us with a diameter of about 100 light years.
CTB1 is a very challenging object to photograph, as it is quite faint. Without the use of filters, in fact, it is practically invisible. In this regard, I believe that the L_Ultimate filter made the difference in this case, since it was a subject at the limit of feasibility from my city sky that I tried to shoot several times with the Newton without particular success.
A curiosity that I came across by chance doing a bit of research on the web: this nebula is also known by the common name of Garlic Nebula and I found a 2015 image on Astrobin (here the link: https: //
www.astrobin.com/208841/C/) where the author literally declares "I couldn't find a common name for it, so I'm calling it for what I see - a head of Garlic". I really believe that this is the origin of its bizarre name.
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