Acquisition details
CAMERA FLI ML8300 (Ha) @ -25C RBI 2s Canon 40D Baader mod (RGB) @ISO1600	LENS/OTA William Optics 66 Zenithstar @F6.1 (Ha) Canon 200mm @F4 (RGB)	FLATTENER/REDUCER TSFlat 2
MOUNT ASA DDM60 Pro	IMAGE Ha: 31x20min = 10hr 20min RGB: 210x3min = 10hr 30min	IMAGE SCALE 2.76 arcsec/pixel (full size)
FIELD OF VIEW ca 150 x 105 arcmin	FILTER Baader Ha 7nm clip in Astronomik CLS clip in	GUIDING Auto guiding with MaximDL OAG Starlight Xpress Lodestar
DATE Jan 27 - 31, 2011	LOCATION Älta, Sweden

On mouse over:         Image details                 HaRGB                 H-alpha

IC 443 (also known as the Jellyfish Nebula and Sharpless 248 (Sh2-248)) is a Galactic supernova remnant (SNR) in the constellation Gemini. On the plan of the sky, it is located near the star Eta Geminorum. Its distance is roughly 5,000 light years (~5×1016 km) from Earth. IC 443 is thought to be the remains of a supernova that occurred 3,000 - 30,000 years ago. The same supernova event likely created the neutron star CXOU J061705.3+222127, the collapsed remnant of the stellar core. IC 443 is one of the best-studied cases of supernova remnants interacting with surrounding molecular clouds

The above text is taken from Wikipedia.

This is a first light image with the ML8300.

After a few images I noticed that the Jelly Fish was a very faint object with low surface brightness. This was obvious from the RGB images shot with a Canon DSLR. Light pollution prevented me from taking long subs - I had to settle with 3min (with the Astronomik CLS light pollution filter). Even thou I have more than 10hours it is still very faint in the RGB only image. The DSLR version of the image can be found here.

With the Ha filter on the ML8300 taking long subs was no problem.

I enlarged and cropped the DSLR image to provide colour to the ML8300 Ha image. I added Ha to the red channel (20% RGB + 80% Ha) and just a bit to the blue channel (10%) to simulate Hbeta. Finally I also used the Ha data as luminance, which I know is not strictly ok, but I IC443 is dominated by Ha. This was supported when I tried to take some OIII subs. I tried both 2x2 and 3x3 binning to increase sensitivity, but the result was basically no OIII data at all.

By "mouse over" on the blue text just below the image you can see:

• Image details: Equipment used, number of subs etc.
• HaRGB: a combination of the RGB (DSLR) image with the Ha (ML8300) image, where Ha is used in the red (80%)and blue (15%) channel and the green & blue is used also for luminance. For a 50% image click here
• H-alpha: image using only the Ha data. For a 50% image click here.

An enlarged (50%) colour image can be viewed here and an enlarged (50%) Ha image can be viewed here.

The following software has been used. MaximDL (image acquisition and guiding), CCDStack (calibration and RGB scaling), PixInsight (cropping, background correction, colour corrections) and Photoshop CS5 (all the rest, incl Noel Carbonis Astronomy Tools).

This image was processed in January 2011