Wednesday, August 26, 2009

Hercules Globular Cluster M13 and QHY8


I have always wanted to be able to capture compelling images of the globular clusters. Visually, these are some of the nicest objects because many are bright enough in the eyepiece to draw your attention and are pleasing to explore. In a finely focused scope you can see the less dense outer regions give rise to the typically compact and crowded core. Increasing the magnification draws out increasing detail up to the point the scope and seeing can go no further.

I have seen many images of this class of object and was pleased to see how this turned out.

I think there was some icing on the CCD in the QHY8 camera as I have no other explanation for the odd dark regions along the bottom of the image.

Object Info

M13 was discovered by Edmond Halley in 1714 and is also called the 'Great globular cluster in Hercules'. It is one of the most prominent and best known globulars of the Northern celestial hemisphere.

M13 is 25,100 light years from earth and contains more than 100,000 stars. The age of M13 has been determined to be 14 to 24 billion years old.

Field Details
Date/Location: Monday August 24, 2009, 9:47pm at Ottawa Ontario
Instrument: QHY8, through Celestron SCT C11 w/o Focal Reduction
Filters: None
Mount: Celestron CGE
Focal Ratio: Imaging at f/10, guiding at f/4.3
Guiding: Auto through William Optics Megres 90mm w/ Meade DSI and f/6.3 FR
Conditions: Visually clear with moderate humidity
Weather: 20 deg. C
Exposure: 25 minutes total in 5 x 5 min exposures (Gain 0 Offset 65)
Focusing: Imaging with Stark Labs Nebulosity 2.0 (HFR 1.6 typical)
Image Capture: Imaging with Stark Labs Nebulosity 2.0 (5 exposures taken)
Autoguiding: Stark Labs PDH

Exposure Details and Processing
Stacking: 5 of 5
Pixel Math: Zero Mean applied
Levels/Stretch: Done in Neb2
Binning: none

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