| Description | M4 was discovered by Philippe Loys de Chéseaux in 1745 and catalogued by Charles Messier on May 8, 1764, only 5 days after M3: "Cluster of very small [faint] stars; with an inferior telescope, it appears more like a nebula; this cluster is situated near Antares & on its parallel". <--> M4 is much less dense than other Messier GC's. I believe this is the ONLY GC in the Messier catalog where he was able to resolve individual stars. Compare it to his description of M3, for example: "it doesn't contain any star, its center is brilliant, & its light is gradually fading away." Or, more tersely in many other, later objects: "Nebula without stars". M3 is the second brightest GC in the Messier catalog at Apparent Magnitude 5.63 and the largest at 36'. The "Spider" cluster is an appropriate nickname and exhibits an unusual line of brighter stars just slightly off-center, evincing the spider's "back". This was an opportunistic capture on a night when the weather forecast did not predict observable weather. When it turned clear, I quickly set up the SeeStar. This time of year I'm normally using my 8" EdgeHD... but the SeeStar's focal length suits this target nicely with its wider field of view: The poor transparency resulted in a "brownish" tinge to the original image (visible in the "annotated" gallery image). I was able to adjust the color-balance in the final gallery images to reveal both blue and red giant stars. |
