Celestial hemisphere:  Northern  ·  Constellation: Auriga (Aur)  ·  Contains:  HD31855  ·  HD32050  ·  HD32296  ·  LBN 747  ·  LBN 754  ·  LBN 759  ·  Sh2-219  ·  Sh2-221
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Sh2-221, Roger Nichol
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Sh2-221

Getting plate-solving status, please wait...
Sh2-221, Roger Nichol
Powered byPixInsight

Sh2-221

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Description

Sh2-221 is a large supernova remnant in the Auriga constellation. It is very faint, requiring a lot (46 hours) of integration to make it visible, hence it is not very commonly imaged.  This took 4 months of imaging to capture sufficient light. 

The Ha and Oiii components have quite distinct structures. I have used a HOO power-of-inverted-pixels palette to enhance this and show the areas where there is a strong mix of the gases. 

There is another small but relatively bright nebula to the upper right, Sh2-219.

For the first time, I purified the Ha and Oiii by subtracting a small fraction of the Ha that is picked up in the Green and Blue channels and the smaller fraction of Oiii that ends up in the Red channel, it did make a small but noticeable improvement in contrast between the gases.

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Sh2-221, Roger Nichol