Wednesday, 20 October 2021

NGC 6888 The Crescent Nebula

Time for my latest image.  This Autumn, I've started taking data from several nights, and then combining it all to make a single image.  Previously, I have always tried to get all my data for a single image on the same night.  Added to that, I've also started doing meridian flips during my imaging so I can continue imaging as the target moves across the meridian.  It's so straight forwards, I can't believe it's taken me this long to actually having the confidence in doing it!

Anyway, onto the image.  I'm still really enjoying using the Altair Hypercam 183c v2 and combined with the quadband filter, it continues to impress me.  Learning a bunch of new processing techniques in PixInsight has made me appreciate how different images can be produced from exactly the same start point in the same dataset.  

NGC 6888 is well place for imaging as soon as it gets dark at the moment for people in the UK.  It's almost direct overhead and is well framed in the field of view of my imaging rig.  It's an emission nebula, around 5000 light years away in the constellation of Cygnus.


The nebula itself when looked at in a proper wide view image, sits in amongst a vast area of fainter nebulosity visible in this area of Cygnus.  The base dataset for this image consists of around 3 hours of data taken in brief windows of opportunity over 3 nights, and using the quadband filter, it is possible to start to bring out this nebulosity in the background.  Also, the more I use PixInsight, the more I am learning about the use of masks to help protect or enhance specific areas of the image.  Using some of these techniques slightly differently from one attempt of the data processing, produced a different image where some of the background nebula was really pulled out a bit more.


There's a huge amount more detail to come out from the background.  Some images produced by other imagers I have read about are composed from two different datasets.  The first concerning the target of NGC 6888 itself, and then a second dataset concentrating on the background nebulosity.  Nevertheless, I'm extremely pleased with how both the images have turned out.  The higher resolution versions which haven't been resized and compressed show much better clarity when zoomed in, so I have lost a bit of detail in these images.

Thanks for reading, and clear skies!

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