Archive for June 2016

M5 Globular Cluster in Serpens and The Mystery of The Ruby Eyes

June 26, 2016

Globular Cluster M5 and the Ruby Eyes.   Be sure to click on the following link for the complete report….


10-inch reflector @ 208x:   Pencil sketch using a blank 5 x 8 blank notecard with the colors inverted via a scanner.  Note the dark lane on the northern edge, and the chain of stars on the  leading of the SSW  edge of the cluster.  RI Scanned Image 161780000

The following image was made using a 4-inch refractor by Dr. James Dire of Hawaii.  Please note the dark lane on the northern edge as shown in the previous pencil sketch.   


The following Image by James Dire using a 10-inch reflector….again note the northern dark lane, and the chain of stars extending SSW away from the cluster, as shown in both images.


Visual notes as following by the writer.  RI

M5 – NGC 5904 – Globular cluster in Serpens – Observer: Roger IvesterDate: May 27, 2016
Telescope: 10-inch f/4.5 Reflector
Magnification: 208x
FOV: 0.39º NELM: 5.0

Very bright, easily seen through an 8 x 50 finder. At magnitude 5.7, the cluster should be visible naked eye from a dark site. Well concentrated and dense in the central region, with many stars resolved at 208x. When using averted vision, a chain of stars encompasses the northern edge, creating a subtle void between this chain and the main cluster. Also with averted vision, a very faint chain of stars lead off toward the SW. A halo surrounds the main cluster in a mostly circular shape, with many outlier stars embedded in the halo and extending well beyond.

Telescope: 102 mm f/9.8 refractor
Magnification: Eyepiece 26 mm + 2.8x Barlow = 108x

Bright with a well concentrated center and much brighter more intense core. Little to no resolution, however, many brighter outliers are visible. A chain of five stars are easily seen on the north edge of the cluster. The most prominent feature of this cluster, using the 102 mm refractor is the triangular shaped core.  Notes by Roger Ivester


The following write-up/article by Dr. James Dire, which accompanies the two images as posted above. 

By Dr. James R. Dire
M5 is one of the finest globular star clusters north of the celestial equator. Located in Serpens Caput, the cluster is very easy to find. It is 8th degrees due east of 4th magnitude 109 Virginis, 11.5 degrees north of Beta Librae, and 7.5 degrees southwest of Alpha Serpentis. The cluster is a mere 20 arcminutes northwest of 5th magnitude MQ Serpentis (or 5 Serpentis).

M5 was discovered by Godfried Kirch in 1704. Kirch discovered it while looking at a comet nearby. Charles Messier catalog it in 1764. The integrated magnitude of the cluster is 5.6 and its diameter is 28.4 arcminutes. The cluster is an easy find in binoculars!

M5 contains hundreds of thousands of stars. Of those, nearly 100 are known to be RR Lyrae-type variable stars. These variable stars pin down the distance to the cluster at 24,500 light years. The cluster is one of the largest globular clusters in the Milky Way spanning 165 light years. Any object within 200 light years of M5’s center would be gravitationally bound to the cluster, unless moving with a radial velocity equal to the cluster’s escape velocity. M5 is thought to be 13 billion years old, one of the oldest globular clusters known.

Nearby 5 Serpentis is a binary star with components of magnitude 5.0 and 10.1, separated by 11.4 arc seconds. Slightly more than two degrees south of M5 lies another globular cluster known as Polomar 5. Located three times farther away than M5, Polarmar 5 shines at magnitude 11.75 and is 16 arcminutes in size.

I offer two images I took of M5. The first was taken with a 4-inch f/7.9 Stellarvue 102mm APO. The exposure was 30 minutes with an SBIG ST-2000XCM CCD camera. The bright star partial cut off to the lower left of the cluster is MQ Serpentis! The second image was taken with the same camera on a Discovery 10-inch f/6 Newtonian with a Televue Paracorr II coma corrector. The exposure was 60 minutes. The images speak for themselves!  James Dire