Optical detection and spectroscopic confirmation of supernova remnant G213.0-0.6 (now redesignated as G213.3-0.4)

During a detailed search for optical counterparts of known Galactic supernova remnants (SNRs) using the Anglo-Australian Observatory/United Kingdom Schmidt Telescope (AAO/UKST) Hα survey of the southern Galactic plane we have found characteristic optical Hα filaments and associated emission in the area of SNR G213.0-0.6. Although this remnant was previously detected in the radio as a non-thermal source, we also confirm emission at 4850MHz in the Parkes-MIT-NRAO (PMN) survey and at 1400MHz in the NRAO/VLA Sky Survey (NVSS). There is an excellent match in morphological structure between the optical (Hα) and radio emission. We subsequently obtained optical spectroscopy of selected Hα filaments using the South African Astronomical Observatory 1.9-m telescope which confirmed shock excitation typical of supernova remnants. Our discovery of Hα emission and the positional match with several radio frequency maps led us to reassign G213.0-0.6 as G213.3-0.4 as these coordinates more accurately reflect the actual centre of the SNR shell and hence the most probable place of the original supernova explosion. Support for this new SNR ID comes from the fact that the X-ray source 1RXS J065049.7-003220 is situated in the centre of this new remnant and could be connected with the supernova explosion.