The total number of supernova remnants (SNRs) is estimated by different methods, and it is generally accepted to be about 300-1000 detectable SNRs in the Galaxy. Green's (1998) catalog includes 220 confirmed SNRs and several dozens of possible or probable ones. Most of them are radio SNRs. Thus a search for new SNRs is an important task of observational radio astronomy. Such searches have been made by Whiteoak & Green (1992), Gray (1994a , 1994b), Duncan et al. (1997). Using the radio morphology, Weiler (1983) divided the Galactic SNRs on three classes of shell-like, crab-like or plerionic and mixed or composite ones. As a rule, in these searches the shell or composite SNRs have been found, and the shells dominate the total sample.
Trushkin (1996 , 1998) searched for new SNRs in the Galactic plane survey with the RATAN-600 radio telescope in the First and Fourth Galactic quadrants between and and at 0.96, 3.9 and 11.2 GHz. A dozen extended non-thermal sources which could be new SNRs have been revealed. A analysis of the NRAO VLA Sky Survey (NVSS) maps (Condon et al. 1998) is extremely helpful for such a search in the Galactic plane. In spite of the apparent insensitivity of NVSS to extended radiation, nearly 80 known Galactic SNRs are visible in NVSS maps. Trushkin (1999a) created the collection of the SNR images that is released via the World Wide Web. This induces us to search for new shell SNRs in the original NVSS maps. Excluding known HII regions or planetary nebulae, we have selected nearly 20 shell SNR candidates. One of them, G16.2-2.7, shows all the necessary properties to recognize it as a new SNR.
© European Southern Observatory (ESO) 1999
Online publication: December 2, 1999