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Tuesday, January 27, 2015

Jellyfish Nebula, IC 443, a supernova remnant in Gemini

This winter season has been worst I have seen in fifteen years. We have now had almost constant cloud cover for about three months. There was a partially clear sky for couple of nights and I managed to use it, since my observatory is located just next to my home. The night between  18. and 19. of January was kind of clear but the seeing and transparency was very poor. I was about to toss away all of the frames for IC 443 but since I haven't anything else to process, I kept them. Here are the results, I did the best I could with a low quality material. This object will need much more exposures in future.

IC 443, the Jellyfish Nebula SNR

IC 443 in H-alpha light alone, four hours of integration time.


IC 443, Jellyfish Nebula, Sharpless 248 (Sh2-248), is a galactic supernova remnant in the constellation Gemini. It locates near the star Eta Geminorum (A bright star at middle right) at distance of about 5000 light years. This supernova event very likely created a neutron star (CXOU J061705.3+222127), a collapsed remnant of the stellar core. Nebula spans about 50-70 light years. This photo has an angular size of about one arc minute. (Full Moon has an apparent size of ~30 arc minutes.)

An older wide field photo of the same object

Image is in mapped colors from the emission of ionized elements, Hydrogen, Sulfur and Oxygen.
Original blog post of this image with technical details can be seen HERE

A color version of IC 443
Colors from Sulfur and Oxygen are borrowed from the photo above

Image is in mapped colors from the emission of ionized elements, Hydrogen,
Sulfur and Oxygen. Oxygen and Sulfur are from an older wide field photo.

An experimental starless view

In this experimental starless image, the actual remnant stands out nicely. The deep red
color is from the Hydrogen alpha emission, the strongest emission line of  the hydrogen.

Technical details

Processing work flow
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight
Color combine in PS CS3
Levels and curves in PS CS3.

Imaging optics
Celestron Edge HD 1100 @ f7 with 0,7 focal reducer for Edge HD 1100 telescope

Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x2
Astrodon filter, 5nm H-alpha

Exposure times
H-alpha, 12 x 1200s = 4h

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