M1 - Crab Nebula ([SII]:Ha:[OIII])
M1 - Crab Nebula ([SII]:Ha:[OIII]): The Crab Nebula in Taurus is the remnant of a supernova that was observed exploding in 1054.
Right Ascension: 5hr 34.5m
Declination: 22d 01m
Apparent Magnitude: 8.4
Date: October 2009
Telescope: Meade 16" Schmidt Cassegrain with f6.3 reducer
Camera: SBIG ST-10XE
Guiding: Meade 5" refractor/DSI Pro/PHD
Filters: AstroDon 6nm Ha, [SII], and O[III] narrow band filters.
Red: [SII] 5x10min
Green: Ha 8x10min
Blue: [OIII] 5x10min
Processing Notes: The camera was at -40C, and a Sigma Beta combine of five 10 minute darks was used. This image had 18 ten minute sub-exposures and they were ALL used. (This is somewhat unusual.) The data was reduced and aligned in CCDStack. Individual colors were combined in Sigma Beta, and saved as 32bit FITs. These files were imported to Photoshop using a Fits Liberator sqrt(x) stretch function. Noise was reduced using the Photoshop "reduce noise" function, and the dim areas also got a minor gaussian blur. The separate channels were further stretched to achieve similar histograms, and then combined as an RGB image. A false luminance was created by merging the three channels and sharpening the bright areas slightly.
Links to images of this object on other sites:
Additional Comments: The seeing for these two nights was ~4/10 and the moon was almost full. An improvement would be to gather more [SII] and [OIII] data and also data through a clear filter on a dark night with good seeing. The luminance could then be used to sharpen up the filaments in an LRGB image.
Several other images of the Crab Nebula can be found on this web site by searching for M1.