POSS-IISecond Palomar Observatory Sky Survey
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This location is just east of the position shown on the POSS-II red plate, a change in position that correlates with the SNR's expansion rate of ~0.
The ones in this article were generated by combining the red and blue POSS-II plates from the Digitized Sky Survey (DSS); similar results can be obtained from WikiSky or the Aladin Sky Atlas.