Sunday, June 7, 2015

M13 - My first globular cluster!

Weird - after almost 3 years, I took my very first image of a globular cluster:

(click on image for a high-resolution version)

This is M13 - detected by Edmund Halley in 1714. It is 145 light years in diameter and is about 25,000 light years away from earth.

In 1974, we sent a message (the so called Arecibo Message) to this cluster. It was designed by Dr. Francis Drake and Carl Sagan. It consisted of:

  1. The numbers one (1) to ten (10)
  2. The atomic numbers of the elements hydrogencarbonnitrogenoxygen, and phosphorus, which make up deoxyribonucleic acid (DNA)
  3. The formulas for the sugars and bases in the nucleotides of DNA
  4. The number of nucleotides in DNA, and a graphic of the double helix structure of DNA
  5. A graphic figure of a human, the dimension (physical height) of an average man, and the human population of Earth
  6. A graphic of the Solar System indicating which of the planets the message is coming from
  7. A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish

It will take 25,000 years until this message reaches the cluster and (unless civilizations there have developed technologies that allow them to travel faster then light) will take another 25,000 years until we might hear back.

A cropped version:

Data Collection was surprisingly easy. These are just 10x10min exposures in RGB (no Luminance!)

Processing in Pixinsight was easy too:
  1. Used the BatchPreprocessing script to create RGB images
  2. Combined with LRGBCombination
  3. Gradient removal with DBE (3 times!)
  4. BackgroundNeutralization and ColorCorrection
  5. Stretched with MaskedStretch (to avoid stars growing)
  6. Further stretch with HistogramTransformation
  7. HDRMultiscaleTransformation (before, the core was overblown)
  8. Final stretch (RGB, Lightness, Saturation) with CurvesTransformation
Not bad...

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