A new galactic supernova remnant, G312.4–0.4

A new continuum map at 408 MHz is presented for a portion of the galactic plane near longitude 312°. Comparison with 5000-MHz measurements of similar angular resolution (several arcminutes), in both the radio continuum and hydrogen recombination lines, has allowed us to distinguish a hitherto unnoticed supernova remnant (SNR), G312.4–0.4, with angular diameter ~0°.5 and distance ~5 kpc. Other discrete sources on the map include: (i) a previously known SNR, G311.5–0.3; (ii) four sources that are non-thermal and most likely extragalactic; (iii) 16 H II regions, of which two are located in an extremely distant portion of the Carina spiral arm, ~ 16 kpc from the Sun, with galactocentric radius ~ 12.3 kpc.