Messier 05 is a Globular Cluster located in the constellation of Serpens Caput (the Snake Head), and makes for fine viewing with the mix of orange and blue stars and pairs well with the bright star 5 Serpentis. The cluster is comprised of over 100,000 stars and is located approximately 25,000 light years away from Earth. Whilst we can see 5 Serpentis in the same field of view as the cluster, the star is only 83 light years away so is much closer.
5 Serpentis is a binary star. The primary component (5 Ser A) has a visual magnitude of 5.1 whilst its companion (5 Ser B) has a magnitude of 10.1 and is separated by 11.4 arc seconds. I would like to be able to claim that I have captured this binary companion with the small orange star that we can see very close to 5 Serpentis in the image but alas, I cannot do this. Or I suppose I could claim this but I would be incorrect in doing so
Using the Stellarium planetarium program to measure the angular separation between these two stars in the image, I find that the separation is 34 arc seconds. The actual binary companion is buried in the glow from the primary star.
Link to Astrobin image here.
Click on image in Astrobin for larger resolution.
Click and zoom on image on Flickr here.
CS,
Rodney