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Contains:  IC 444, IC 443, The star Propus (ηGem)
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IC443 Jelly Fish Nebula, 


IC443 Jelly Fish Nebula

IC443 Jelly Fish Nebula

Technical card

Resolution: 3149x2389

Dates:Jan. 31, 2016Feb. 2, 2016Feb. 3, 2016Feb. 4, 2016

Astronomik Ha 12nm 1.25": 51x600" -10C bin 1x1
Astronomik OIII 12nm 1.25": 51x600" -10C bin 1x1
Astronomik SII 12nm 1.25": 52x600" -10C bin 1x1

Integration: 25.7 hours

Darks: ~30

Flats: ~30

Bias: ~100

Avg. Moon age: 23.63 days

Avg. Moon phase: 35.06% job: 947744

RA center: 94.542 degrees

DEC center: 22.567 degrees

Pixel scale: 2.199 arcsec/pixel

Orientation: 177.831 degrees

Field radius: 1.207 degrees

Locations: Lighthouse Observatory, Burleson, Texas, United States


IC 443 (also known as the Jellyfish Nebula) is a Galactic supernova remnant in the constellation Gemini. Located near the star Eta Geminorum, its distance is roughly 5,000 light years from Earth. IC 443 may be the remains of a supernova that occurred 3,000 - 30,000 years ago. The same supernova event likely created a neutron star, the collapsed remnant of the stellar core. IC 443 is one of the best-studied cases of supernova remnants interacting with surrounding molecular clouds.
IC 443 is an extended source, having an angular diameter of 50 arcmin (the full moon is 30 arcmin across). At its estimated distance, it corresponds to a physical size of roughly 70 light years.
Its optical and radio morphology is shell-like, consisting of two connected sub-shells with different centers and radii. Unlike the Crab Nebula, the inner X-ray emission is not dominated by the central pulsar wind nebula. IC 443 shows very similar features to the class of mixed morphology super nova remnants. Both optical and X-ray emission are heavily absorbed by a giant molecular cloud in the foreground, crossing the whole remnant body from northwest to southeast.
Multi-wavelength observations show the presence of sharp density gradients and different cloud geometries in the surroundings of IC 443. Massive stars are known to be short lived (roughly 30 million years), ending their life when they are still embedded within the progenitor cloud. Thus, it is not surprising that the SNR IC 443, which is thought to be the aftermath of a stellar explosion, evolved in such a complex environment. For instance, an appreciable fraction of supernova remnants lies close to dense molecular clouds, and most of them (~60%) show clear signs of interaction with the adjacent cloud. [Source: Wikipedia]

The image was captured with the TMB80SS (mounted on the Meade 12"LX200). The optical train included the Atik 383L+m, EFW2 and Orion Field Flattener at F6.3 (i.e. native 504mm FL). Guiding was accomplished with my new Solomark F50 guidescope and Lodestar camera combo. Astronomik's Ha, OIII and SII narrow band filters were used. All subs were taken at 1x1 bin, -10C, and 10 minutes each.

Image -- 2016
Ha : 51 subs (8.50 hr) on Jan 31st, Feb 2nd, 3rd and 4th.
OIII : 51 subs (8.50 hr) on Jan 31st, Feb 2nd, 3rd and 4th.
SII : 52 subs (8.67 hr) on Jan 31st, Feb 2nd, 3rd and 4th.

Color mix for the image was done per the Hubble palette:
Red = SII, Green = Ha, Blue = OIII

Processing was done with PixInsight. Each filter set was integrated, processed and stretched. These were then combined with PixelMath per the Hubble palette. This final image was further processed in PI, bringing it to the level presented. North is up, and this is a modest crop due to some initial flexure issues.

As with my previous effort (NGC1499 the California Nebula), there was substantial differential flexure between the TMB80SS (mounted atop the LX200) and the Solomark F50 guidescope (mounted in place of the original Meade 8x50 guidescope). I believe the ADM/Losmandy mounting rings, clamps and dovetail rail were/are not sufficient to hold steady the TMB80SS (with camera, filter wheel and flattener). I also suspect there is some flexure in the TMB80SS focuser. For these things I tightened up all that I could and added some elastic to reduce the axial weight of the optical train. I also moved the Solomark from the Meade guidescope mount directly to the TMB80SS. For lack of anything else, I used nylon tie straps to attach the Solomark's dovetail to the TMB's outer shell. This appears to have worked very well. In moving the Solomark, I also found that its draw-tube had a wobble. This was sizable and may have been the major cause of the differential flexure. This was fixed by tightening setscrews in this area. After all of this work, I believe there is virtually no star trailing in the images. FWIW, I did use the images shot on Jan 31st that did have the flexure issue. However their integration into the Feb 2nd, 3rd and 4th subs pretty much eliminated the star trailing affect.



License: None (All rights reserved)

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IC443 Jelly Fish Nebula,