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Sinus Iridum

Sinus Iridum Sinus Iridum ©2018 Frederick Steiling
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Target Information
Main Target Designation(s) Sinus Iridum
Companion Objects Montes Jura, Mare Imbrium, Sinus Roris
Date(s) of acquisition 27Feb2018
Location Definance, MO
Moon Phase 88.0%
Capture resolution 1280x960
Video source 300" at 3.013ms / 26fps
Gain 0%
Stack 405 (5%) of 8096 frames
Video source 60" at 7.010ms / 26fps
Gain 0%
Stack 162 (10%) of 1618 frames
Video source 60" at 9.050ms / 27fps
Gain 0%
Stack 162 (10%) of 1621 frames
Video source 60" at 7.760ms / 27fps
Gain 0%
Stack 162 (10%) of 1621 frames
Imager ZWO ASI120MM
Filters ZWO 1.25" LRGB
Telescope/Lens Celestron C14 XLT SCT
Focal Length 3910mm at f/11
Mount Celestron CGE Pro
Focuser Moonlite 2.5" CSL
Focusing Moonlite Mini V2 High-res Controller
Acquisition FireCapture 2.5
Guiding FireCapture 2.5
Processing AutoStakkert!3, PixInsight 1.8, Photoshop CC

In my effort to go at lunar shots with more deliberate planning, I pointed the C14 at a remarkably interesting landscape and mineral feature on a rare clear night in February.   The Sinus Iridum, a bay extending off the much larger Mare Imbrium to the southeast, is a huge 242 x 157 mile (400 x 260 km) impact crater that has been filled by subsequent lava flow, generating the resulting expansive flatland at the northeast portion of our side of the moon.  Cradling it in crescent arms is the mountain range Montes Jura, boasting peaks that extend over 20,000ft (6100m) in elevation with mountainous bookends of the Promontorium Heraclides (south) and Promontorium Laplace (east) on each side.  One can imagine the view from this lunar bay is nothing short of breathtaking!

I once again chose to shoot the lunar landscape in color, and for good reason here.  There is a fascinating rift in color near the entrance to the Sinus Iridum between rusty tones and bluish hues.  While both colors provide us evidence of rich iron content, the blue areas boast a high titanium content while the rusty areas constitute a more magnesium-rich composition.  One might surmise that the exact flow or timing of lava flows that filled the Sinus Iridum and the much larger Mare Imbrium formed streams and divisions that resulted in these variances.

At the focal length of the C14 and with the tiny pixels of the ASI120MM camera, this image was again an endeavor in battling poor atmospheric seeing and a turbulent jet stream, both commonalities here in the midwest US.  Wavelet processing remains a key component of sharpening these high focal length images, something I've typically relied on Registax 6 to provide.  However, I've taken a different approach here and have performed the bulk of processing in PixInsight, utilizing the Multiscale Linear Transform for my wavelet application.  By comparison, I much prefer the stability and range of noise control available with the MLT process.  However, as a corollary to my experience in Registax 6, there remains quite a bit of guesswork involved in determining an ideal set of parameters to give a natural, not-over-sharpened representation of this feature-rich area.  Regardless, being my first full such attempt in PixInsight, I am very encouraged by this result and am sure more practice and applications on other areas will reveal much greater power in resolving these types of fascinating areas.

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