Messier 45, commonly known as the Pleiades, is an open cluster found in the constellation Taurus. Messier 45 is surrounded by a dusty reflection nebula, which accounts for its blue coloration, along with some pinkish-red coloration due to an ionized gas component. The small 17.3 magnitude galaxy PGC 13696 can be seen to the right of the star Electra (17 Tau), which is the bright star to the right of center.
The data was previously obtained on the nights of November 1st, 2nd, and 3rd, 2013 with a OSC SBIG STF-8300c camera and Takahashi E-130D f/3.3 Astrograph on a Paramount (Mayhill, NM). Total integration time was 4 hr 20 min (26 x 10 min lights @ -20 degrees C; 20 darks; 64 flats, 64 bias). Calibrated, registered, integrated, and processed in PixInsight 1.8.3.1123.
Some comments on processing: The calibrated, registered, and integrated OSC image was duplicated and the R, G, and B channels extracted. The R, G, and B channels were combined with the Integration Tool to prepare a synthetic luminance (SynL). Dynamic Background Extraction ( DBE) and Deconvolution applied to the SynL image. DBE, Background Neutralization, and Color Calibration was applied to the original RGB image. Both the RGB and SynL images were stretched (Masked Stretch tool). The luminance (“lightness” using L*a*b*) was extracted from the RGB image and the Linear Fit tool was used to match the stretch of the luminance to the SynL channel (SynL as reference). The fitted luminance was added back to the RGB image using the Channel Combination tool in L*a*b* mode. The SynLRGB image was made using LRGB Combine tool. Further processing included noise reduction, multiscale processing to bring out faint structure, color saturation, sharpening, and contrast enhancement.