Zenfolio | RASC Victoria Centre | Dan Posey | Messier 1 - the Crab (Plaskett data)
Uploaded 2-Dec-17
Taken 2-Dec-17
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Dimensions1005 x 1267
Original file size782 KB
Image typeJPEG
Color spacesRGB
Date modified2-Dec-17 12:38
Messier 1 - the Crab (Plaskett data)

Messier 1 - the Crab (Plaskett data)

5x3m GPrime, 3x3m RPrime, 3x3m IPrime for 33 minutes of total exposure. The frames were captured with a EV2CCD at -102*C with a peak QE of 84% near the red end. We were shooting at a focal length of ~9250mm with a 2x2 bin on the EV2, giving us sampling at 0.62"/pixel, and we shot unguided for the night. I have cropped the frame down a bit, as some sloppy processing choices introduced some noise in areas that were pulled up with flat frames. The image is false colour, with GPrime mapped to B, RPrime to G and IPrime to R. As a result, the typical red emission areas surrounding the nebula are green in this example. The lopsided capture helped balance the channels, as the QE drops a fair bit towards the blue end of the spectrum. I didn't bother cleaning up the bad column or dead pixels in the first run, as we didn't need darks, so I don't have one to build a defect map.