A new composite supernova remnant of low surface brightness – G322.5 – 0.1

A composite supernova remnant, |$\text G 322.5-0.1$|⁠, has been discovered in a survey of the southern galactic plane at 843 MHz with the Molonglo Observatory Synthesis Telescope. The remnant consists of a roughly circular shell of diameter 15 arcmin, an elliptical plerionic component of extent |$5\times3 \enspace \text{arcmin}^2$| at its center, and a number of bright knots that are confined to the eastern half of the remnant. The total flux density at 843 MHz is 2.0 Jy, and the mean surface brightness is |$1.5\times 10^{-21}\enspace\text {W m}^{-2} \enspace \text {Hz}^{-1}\text {sr}^{-1}$|⁠, giving |$\text G 322.5-0.1$| the lowest surface brightness of any known composite supernova remnant.