NGC 253

[References]

CANGAROO-II: Itoh, C. et al., Astronomy and Astrophysics 396, L1-L4 (2002),
       Itoh, C. et al., Astronomy and Astrophysics, 402, 443-455 (2003)
       Erratum: Itoh, C. et al., Astron. Astrophys. 462, 67-71 (2007)

H.E.S.S.: Aharonian, F. et al., Astron. Astrophys. 442, 177-183 (2005) [upper limit]
            D.Nedbal et al., 30th ICRC (2007) / arXiv:0710.4057 [astro-ph] p.181 [upper limit]
            F. Acero et al., Science 326, 1080-1082 (2009)
            A. Abramowski et al., Astrophys. J. 757:158 (12pp) (2012)
            H. Abdalla et al., arXiv: 1806.03866 [astro-ph]