Messier 13

Messier 13 (M13) is truly a beautiful and magnificent globular star cluster in the Constellation Hercules which was taken with an SBIGSTL-11000M CCD and a RCOS 24-inch telescope at the Mount LemmonSkyCenter.

Messier 13 is truly a standalone globular star cluster and is often referred to as (M13) and was discovered in the year 1714 by Edmond Halley. Messier 13 was cataloged on June 1, 1764 by Charles Messier into his list of objects that were “not” to be mistaken for comets.

Charles Messier’s list which included Messier 13 was to eventually became known as the Messier catalog. It is located at the astronomical coordinates Right Ascension (R.A.) 16 h 41.7 m and Declination (Dec.) +36° 28′. Messier 13 is more often described by astronomers as the most magnificent globular cluster that is visible to astronomers and novice observers in the northern hemisphere.

Locating Messier 13 is pretty easy. It’s observed distance is about a third of the way from the bright star Vega to Arcturus. There are also four rather bright stars in the constellation Hercules which apparently form the well-known Keystone asterism, which is recognized as the broad muscular torso of the Greek hero Hercules.

Messier 13 can easily be seen 66% of the way north (by west) from Zeta to Eta Herculis. Showing an apparent magnitude of 5.8, Messier 13 is somewhat visible to the unaided eye using averted vision without the presence of the moon on dark nights. Messier 13 is rather prominent in just ordinary 7×50 binoculars as sort of a bright, round patch of somewhat modulated light. Its overall stellar diameter is around 23 arcminutes and it is quite easy to view in the smaller aperture telescopes. Telescopes with at least four inches of aperture can resolve smaller stars in Messier 13’s outer extent which is seen through the eyepiece as rather small pinpoints of light.

However, only the larger refractor or reflector telescopes with greater apertures of over 6 inches can resolve stars further into the center of the Messier 13 cluster. For those who enjoy viewing the Messier 13 cluster, it is normally visible (weather permitting) throughout most of the calendar year from latitudes (greater than 36 degrees north), with the longest visible observing period (weather permitting) during planet earth’s northern hemisphere’s typical spring and summer periods.

Somewhat close to Messier 13 is a visually impressive 12th-magnitude edge-on galaxy NGC 6207 that lies approximately 28 arcminutes, which is located directly northeast of Messier 13. There is also a somewhat smaller galaxy, IC 4617, that is located about halfway between NGC6207 and Messier 13 and it can be found north-northeast of the larger globular cluster Messier’s 13 galactic center. Observing using low magnification, the impressive cluster can be viewed with a telescope being bracketed by two nearby seventh–magnitude stars.

The globular cluster Messier 13 is nearly 145 light-years (One light year equals 6 trillion miles) in its overall diameter and is composed of several hundred thousand stars, with estimates varying from around 300,000 to over 500,000 stars or more.

Messier 13 has a distance that is about 22,200 to 25,000 light-years away from planet Earth, and the Messier 13 globular cluster is one of over one hundred (or more) globular clusters that are known to orbit the central region of our Milky Way galaxy. The stars that are of the singular variety in this particular globular cluster were first resolved as far back as 1779.

Comparing the stars in the relative neighborhood of the Sun, the stars that makeup the population of the Messier 13 globular cluster is somewhat dense and closely packed together and sometimes collide at times with each other and produce new stars.

These are classified as (astronomically speaking) particularly young stars which are recently formed and are commonly known as the “blue stragglers” and are of cosmic interest to astronomers. 

It’s interesting to make note of the last three stellar variables (V63, V64, and V65) that were discovered from an observatory located somewhere in Spain in the years that range from April 2021, March 2022, and January 2024. Perhaps we will see more data about these particular newly discovered variable stars in the future. 

Please note the source: From Wikipedia, the free encyclopedia. Norman Butler (Ph.D.) is also an astronomer who worked at the Haleakala Observatory (10,013 ft. elev.) on Maui, Hawaii starting in the early 1980s for AVCO Everett Research Laboratory along with the U.S. Air Force. Part of Norman’s more important work at the high-altitude Haleakala Observatory was to track satellites and the space shuttle as well as doing astronomical research on the giant galaxy M87’s “central core” in the Constellation Virgo with a 1.6M telescope.

Norman Butler is originally from Topeka, Kansas and is a 1962 graduate of Topeka High School and a 1960’s U.S. Navy E6 veteran. Butler has a 1972 associate’s degree from San Diego City College along with a 1980’s Bachelor’s and Master’s degree in Physics, including a Ph.D. from a California University. Norman’s also a 1981 RTMC and a 2011 RTMC EXPO Merit Award winning Amateur Telescope and Binoscope maker and author of five popular Amazon books, including Sky & Telescope and Astronomy Technology Today magazines with Butler’s articles and stories about designing, building, and using amateur and homemade telescopes and binoscopes for astronomical observing. Butler is also an astronomer who worked at the Haleakala Observatory on Maui, Hawaii starting in the early 1980s for AVCO Everett Research Laboratory along with the U.S. Air Force.

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