Messier 13 is one of my favorite objects to view through a telescope. In binoculars it is easily seen as a faint smudge in the constellation of Hercules, and it just keeps getting better as the size of the telescope increases. Larger amateur telescopes will show a myriad of closely packed glittering diamonds on a black velvet background. I always take another look at Messier 13 when I have the opportunity.
Messier 13, also known by its New General Catalogue designation of NGC 6205, is one of the most spectacular globular clusters seen in the northern latitudes. It was first documented by Edmond Halley [the discoverer of Halley’s Comet] in 1714. Charles Messier added it to his catalogue on June 1, 1764. At the time Messier did not believe that it contained individual stars. It wasn’t until 20+ years later that other observers such as William Herschel realized that Messier 13 is a large aggregation of closely packed stars.
Messier 13 is believed to contain more than 300,000 stars and is about 25,000 light years distant from Earth. Its size is estimated fo be approximately 145 light years in diameter.
An interesting fact about Messier 13 is that it is the intended recipient of “The Arecibo Message”. In 1974 a radio message containing information about humanity and Earth was beamed directly at Messier 13 from the Arecibo radio telescope in Puerto Rico. It is the hope of the authors of “The Message” that the densely packed stars of Messier 13 will have a better than average chance of harboring an advance civilization that could receive the message. The message will not arrive at Messier 13 for another 25,000 or so years.
This image is a 3 hour luminance and RGB filtered image combination. The luminance channel consisted of 33 x 90 second exposures. Each of the R, G, and B channels were 11 x 240 second exposures. The exposures were calibrated, aligned and stacked in PixInsight. PixInsight’s PhotmetricColorCalibration tool was used for color calibration and background neutralization using G2V as the white reference. Finally, histogram stretching was done in PixInsight and then the luminance and RGB channels were saves as 16 bit TIFF images before export to Photoshop. The luminance and RGB channels were combined in Photoshop and then some layer masking operations were performed to allow visualization of the bright core area.
The photons used for this image were captured by a Stellarvue SVQ100 f/5.8 focal length telescope with an attached ZWO ASI1600MM-C camera. Baader 36mm unmounted filters were used.