IC 443
Sharpless 248 (SH2-248)
The Jellyfish Nebula
IC 443, also called the Jellyfish Nebula, is a supernova remnant in the constellation Gemini, located about 5,000 light-years from Earth near the star Eta Geminorum.
It is believed to be the result of a supernova that happened 30,000 to 35,000 years ago, which also created the neutron star CXOU J061705.3+222127.
IC 443 is a clear example of a supernova remnant interacting with nearby molecular clouds.
Type: Supernova remnant
Distance: 5000 Light Years
Angular size: 50’
Constellation: Gemini
Right ascension: 06h 17m 13s
Declination: +22° 31′ 05″
Finder Chart
You can find IC 443 in the constellation Gemini, near the borders of the constellations Taurus and Orion. The bright star Propus η (Eta) Geminorum sits very close to the nebula's right, and the star Tejat μ (Mu) Geminorum lies to the left of it.
IMAGING GEAR
I captured these images using a 100mm f/4.12 telescope on an APS-C-sized sensor. The field of view for this frame is approximately 3 by 2 degrees. This setup allowed me to highlight the unique structure of IC 443 and its interaction with the surrounding molecular clouds, as well as the nearby reflection nebula IC 444.
If you have a setup with a smaller field of view, you can focus more closely on the intricate nebulosity of IC 443 or the reflection nebula IC 444.
I have also seen images of IC 443 taken with smart telescopes, but to truly showcase its beauty and complexity, one must be prepared to invest some serious integration times.
Telescope: Skywatcher Esprit 100
reducer: *0.75
Resulting focal length: 412mm
f-ratio: f/4.12
Camera: ZWO ASI2600mm Pro
Filtration: Antlia LRGB and 3nm H-alpha, OIII and SII filters
Mount: ZWO AM5 harmonic drive mount
FILTRATION AND EXPOSURE TIMES
You can beautifully capture this nebula in RGB, which will also highlight the nearby reflection nebula IC 444. Narrowband imaging is highly effective. The signal is strongest in H-alpha and SII, and there are beautiful structures in OIII, which makes all of them essential for detailed imaging. However, dual narrowband filters (Ha/OIII) work well too.
To capture the unique and delicate structure of IC 443, I would invest at least ten hours of total integration time on this target.
RGB image
Red integration: 84 minutes
Green integration: 64 Minutes
Blue integration: 72 minutes
Total integration: 220 minutes = 3 hours 40 minutes
Sub-exposures: 120 seconds
Hydrogen-alpha
Total integration:
500 minutes = 8 hours 20 minutes
Sub exposures: 300 seconds
Oxygen III
Total integration:
435 minutes = 7 hours 15 minutes
Sub exposures: 300 seconds
Sulphur II
Total integration:
440 minutes = 7 hours 20 minutes
Sub exposures: 300 seconds
EDITING TIPS
IC 443 responds well to narrowband imaging techniques and looks great in any palette of your choice. However, the reflection nebula IC 444 is best captured using broadband imaging.
HOO
SHO
Foraxx
FINAL EDIT
For this target, I decided to combine narrowband and broadband data to highlight the best aspects of both approaches. This allows me to showcase the intricate emission regions of the nebula, the stunning reflection nebula IC 444, faint molecular cloud structures, and the true colors of the surrounding star field.