This guy has been on my list for a while, but I had to wait for several clear nights to capture it. For such a faint object, several great images of it have popped up on here recently (see
here,
here, and
here, among others), a testament to modern equipment and rising standards in the amateur community.
As you can see, it sits just west of the Fishhead Nebula (IC1795) and the Heart Nebula. It is sometimes referred to as SNR G132.6+01.5 (or...+01.3), but more often by its radio designation of HB3. That catalog, by R. Hanbury Brown and C. Hazard, was one of the earliest radio surveys, published in 1953 using the Jodrell Bank antenna in the UK. A small fragment of H-alpha emission on the western edge was catalogued as LBN641, but the OIII optical emission wasn’t noted until 1982 by Fesen and Gull, though the film was barely able to reveal any details. This supernova is estimated to have exploded about 30-50 thousand years ago.The OIII here is very faint, and interestingly the SII is brighter than the H-alpha. I captured several hours of SII, but I’ve discarded it in this image, as the HOO palette better reveals HB3. I find the structure to be remarkably similar to
SNR G65.3+5.7, where there also appears to be two concentric shells.
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