Located in the southwestern part of the constellation Draco, there are two catalog designations for this galaxy— NGC 5906 and NGC 5907 - because of how it was first discovered and described. William Herschel discovered the bright yellow-red eastern side on May 5, 1788 and George Stoney described the paler galaxy disk obscured by dust lanes in the western half on April 13, 1850. Stoney was using Lord Ross’ giant 72" reflector, which enabled him to detect more details than Hershel could with his 40” reflector.
The “New General Catalogue of Nebulae and Clusters of Stars” (abbreviated NGC) was compiled by John Louis Emil Dreyer in 1888, who decided to designate the bright eastern side of the galaxy that Herschel found as “NGC 5907” and the western side that Stoney observed in order as “NGC 5906.” In so doing, Dreyer kept the Hershel’s and Stoney’s location right ascension measurements in proper order. Today, most consider NGC 5907 the identity of the entire galaxy. The western side is very blue with distinct dust lane details, while the eastern side is much brighter and distinctly yellow and red in color.
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