There is some confusion surrounding Messier 40. Winnecke 4 (also known as Messier 40 or WNC 4) is a double star in the constellation Ursa Major. It was discovered by Charles Messier in 1764 while he was searching for a nebula that had been reported in the area by Johannes Hevelius. Not seeing any nebulae, Messier catalogued this double star instead. Burnham calls M40 "one of the few real mistakes in the Messier catalog," faulting Messier for including it when all he saw was a double star, not a nebula of any sort. Subsequently it has been shown that the stars in WNC 4 are unrelated, being in optical alignment only.The three galaxies to the west of WNC 4, starting with the smallest (closest to WNC 4) are PGC 39934, NGC 4290 and NGC 4284. The very bright star outside of the field of view to the south-southwest but causing intereference in the image is magnitude 5.5 SAO 28346.This image comprises 10 x Luminance (60 seconds each) and 5 x Red, Green and Blue (60, 60 and 48 seconds each), 0.5m f/2.9 ASA Astrograph with FLI ML3200 camera at an altitude of 60 degrees on 2 February 2017.The field of view of the image is 32’ x 21’.
Hills Observatory: 1 January 2013 to 18 January 2020