Celestial hemisphere:  Northern  ·  Constellation: Gemini (Gem)  ·  Contains:  7 eta Gem  ·  Gem A  ·  IC 443  ·  LBN 844  ·  Sh2-248  ·  Tejat Prior  ·  The star Propus (ηGem)
Jellyfish Nebula back-catalogue, Richard Francis
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Jellyfish Nebula back-catalogue

Jellyfish Nebula back-catalogue, Richard Francis
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Jellyfish Nebula back-catalogue

Equipment

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Acquisition details

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Description

The image data for this image were collected during two sessions a year apart, in March 2019 and Feb-Mar 2020; all data long overdue for processing. As the Kepler 4040 camera (and driver) were really new in March 2019 it has been a bit laborious to put everything together. At that time the driver's merge function wasn't optimum so I was collecting high gain and low gain separately, which doubles the amount of data processing needed.

There are a lot of data here, some 660 subframes (half each for low gain and high gain) split into about 1 hour of LRGB (with 60s exposures) and almost 24 hours of SHO (with 600s exposures in 2019 and 300s in 2020). I have not given the breakdown of exposures in the Technical Card as it's way too complicated!

This image includes both the SHO data and RGB star colours, from the 1 hour of LRGB data, though, frankly, they don't make that much difference.

I have imaged this object before and found it difficult to achieve a pleasing result, despite there being plenty of signal in both the Ha and SII channels. In the end my wife (Huguette) produced the best result last time. She said she's going to have a go at this one too ;-)

IC443, also known as the Jellyfish Nebula, is about 5000 light years away and is the remnant of a supernova. The age of the supernova explosion is uncertain, but seems to have been between 3,000 and 30,000 years ago. It occupies an area of sky significantly larger than the full Moon which, given its distance, makes its diameter as about 70 light years. Many supernova remnants take the form of a shell of expelled material; in this case there are two connected shells with different centres and radii.

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