Hi All,
Back to business after reprocessing a few entries especially for CWAS and shipped them off over the weekend. (Man, getting colour accurate pro prints done is expensive, especially on fine art paper!). Anyway, I’m pleased to present my latest offering,
M81 - Bode’s Galaxy
First discovered by Johann Elert Bode in 1774, the grand spiral galaxy M81 (aka NGC3031 or Bode’s Galaxy) is one of the nearest galaxies outside our local group. It is the largest galaxy in a group of 34 galaxies located in the constellation Ursa Major. M81’s gravitational interaction with nearby galaxy M82 has increased its blue starburst and pink HII regions, stripping matter from M82. M81 resides approximately 12 million light years away.
About the image (the blurb for those interested);
The image is a LRGB composition with a total exposure time of 1.6 hours (Lum: 40min; R,G,B; 20min respectively). It was acquired through GRAS3 (TOA-150, ST10XME). Usual drill regarding calibration (bias, flats, darks) along with hot and dead pixel removal in MaximDL. Registered in Registar and combined (Sigma Reject) back in MaximDL. Luminance layer passed through three interations of RL deconvolution in CCDSharp. Tried to go great than 3, but the PSF results were not good enough. Needs more data to undergo a better decon run. On the topic of data (considering its peanuts worth and it screaming for more), there was heavy usage of noise reduction to get image looking aesthetic. I used three noise reduction masks of varying intensities to give the best control over bright and dim region noise – background is still noisy imho! This worked well even though time consuming. Colour balance appeared ok after needing to weight the blue channel by .6 compared to the other channels. Not sure why this occurred, but the background ADU was certainly lower. I’m happy with the saturation as it provides a natural feel. There is a misalignment problem on some stars which resulted in some heavily saturated greens and reds. This was resolved using the healing brush tool set to colour mode – not ideal. Some desaturation of the stars also completed the task. Used the SCM process to highlight the dark lanes, and then reduced the SCM layer opacity to 45% to keep a natural, unprocessed look. Minor adjustments to colour balance – raised the blue shadow +3 and red highlights -5. Think the black point could have been raised a few more points… Seasoned to taste.
Those northern hemisphere folks have all the great galaxies. We've got the nebs.
Hope you like it.
