SIMBAD references

We report the discovery of optical filamentary and diffuse emission from G182.4+4.3 using the 1.5-m Russian–Turkish telescope. We present the optical CCD images obtained with the Hα filter, revealing the presence of mainly filamentary structure to the north-west and filamentary and diffuse structure in the centre, south and north regions of the remnant. The bright optical filaments located in the north-west and south regions are well correlated with the prominent radio shell of the remnant, strongly suggesting an association. From the flux-calibrated CCD imaging, the average [SII]/Hα ratio is found to be ∼ 0.9 and ∼ 1.1 for south and north-west regions, respectively, which clearly indicates that the emission originates from shock-heated gas. We also present the results of X-ray data obtained from XMM–Newton, showing diffuse emission with a very low luminosity of ∼ 7.3 x 10³¹erg/s at a distance of 3kpc in the 0.3–10keV energy band. Furthermore, we find a surprisingly low age of ∼ 4400yr for this remnant, given its large radius of ∼ 22pc.