M13, Globular Cluster


M13 Globular Cluster (NGC 6205), also known as Great Hercules Cluster, is a globular star cluster about 25,000 light years ( 2.36*10^17 km) away from us. It is first discovered by the famous Edmund Halley in 1714, who wrote:

"it shows itself to the naked eye when the sky is serene and the Moon absent"

William Herschel mentioned it in these words:

.. most beautiful cluster of stars, exceedingly compressed in the middle and very rich"

A distance of 25k light years and with the angular diameter of 23 arcminutes, the actual size of this cluster comes out about 150 light years. Towards the center, the star density is about 500 times more than our own solar neighbourhood. If there is a planet in the center of the cluster, the night sky would be blazing with literally thousands of stars much brighter than Sirius and Venus. 

M13 Cluster is also famous because, once we have sent a radio signal to supposed Aliens in this cluster!

Omega Centauri is the largest Globular Cluster in our Milyway Galaxy.. here is the comparison of M13 with Omega Centauri:

This image is a work in progress and I would be collecting more data of this cluster in the coming weeks. Stay tuned!


  1. Celestron C14
  3. SBIG AO8
  4. Astrodon Luminance Filter
  5. Maxim DL
  6. Photoshop

2 hours of exposure, subs: 120 sec