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MetaGuide: M83 galaxy in i'r'g' colors, with Atik 383L+ and EdgeHD 11 with reducer on CGE-Pro

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This is in semi-false Sloan colors, with i' -> red, r' -> green, g' -> blue. This gives a wider spectral range with no gaps, and maps Ha regions to green - just as with the "Hubble Palette" used for narrowband imaging. The colors calibrated by custom code based on UCAC4 field stars with AMASS Sloan photometry. The color calibration was deterministic, with Photoshop CS6 applying only levels. The result for this galaxy helps distinguish the green Ha regions from the old, orange star clusters. Two distant galaxies in the upper left have a similar orange color.

Imaging OpticsCelestron EdgeHD 11 with reducer at f/7
MountCelestron CGE-Pro
Guiding SoftwareMetaGuide with dithering from SGP
Guiding ModeOff-axis guiding with Hutech OAG5
Imaging CameraAtik 383L+
Guiding CameraQHY5l-ii
FocusSGP and RoboFocus on the primary focuser - no mirror locks used
Exposure Time3x20x1m Exposures kept short to avoid saturating
Image Scale0.57" per pixel
Raw FWHMDown to 2.0" in subs
Image ProcessingCalibration and stack in custom software, only levels in Photoshop CS6 - no other processing
Image Processing - OtherColors calibrated with Sloan magnitudes using UCAC4 field stars and custom code
Image AcquisitionSGP
Other SoftwarePECTool, TheSkyX Pro for best guidestar selection with field of view indicator (FOVI)
Other HardwarePyxis OAG Rotator for best guidestar, Telegizmos 365 cover, Long usb cable to outside setup
DateJuly 20-1, 2015
FilterAstrodon Sloan i', r', g'

Close up of core at double resolution (0.28"/pixel). Note the multiple elements in the central region, with color distinguishing bright Ha regions from bright stellar regions. Compare with Gemini image showing double nucleus The star formation is evident in the green Ha regions, while the original nucleus shows as the bright orange feature near the center - corresponding to a mass of 2 million suns. Unseen is the newly discovered intruding mass of 16 million suns.