Telescope: Meade SN6 Comet Tracker at f/3.6, Orion Atlas EQ-G
Camera: Full Spectrum Modified Nikon D5300, Baader Mk III MPCC
Filter: Orion Imaging Skyglow Filter
Guide scope: Astro-Tech 60mm, Meade DSI Pro II, PHD
Exposure: 42x90sec, ISO 200, saved as RAW
Darks: Internal (Long Exposure Noise Reduction On)
Flats: 32x1/15sec, Tee shirt flats taken at dusk
Average Light Pollution: Red zone, Bortle 8, poor transparency, variable haze
Lensed Sky Quality Meter: 18.4 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Backyard Nikon, Deep Sky Stacker, Nebulosity, Photoshop
This was the 5th of 6 test images taken to evaluate the use of a Baader Mk III MPCC with this fast f/3.6 Schmidt. The wide field offered by this telescope does a good job showing deep sky objects in context with the surrounding sky. I was a little concerned how the MPCC would work with globular clusters as prior work with this coma corrector showed that it tends to soften the center of the field a tad. However, the Comet Tracker is not a high resolution scope anyway so I was hoping that this effect wouldn’t be too bad, and it wasn’t! In fact, I couldn’t be happier with the resolution at the center of the field.
Globular clusters are relics of the ancient universe and M13 is no exception with an estimated age of 12 billion years. Their great age is an indication of their unusual stability. One consequence of this stability is that any heavy elements that their stars have made remains buried in their cores and the cluster itself has little, if any, interstellar dust. M13 is one of the few globular clusters with a dust-like feature that can be seen as a dark lane extending to the lower left of the core. It is possible that this dust lane is not really associated with M13, but instead is an independent object that just happens to be in front of the cluster.