AnnMarie's Blog

The North American Nebula (NGC7000) & the neighbouring Pelican Nebula (IC5070) are just 2 of the beautiful cosmic sights to be seen in the constellation of Cygnus, "The Swan". Having undertaken a brief tour of Cygnus last summer, I am encouraged to do so in more depth this year – providing time & weather cooperate for me! To start it off I wanted some Hydrogen alpha (Ha) data for these two beautiful nebulae.

Last week I had the only reasonably clear night for some time and so set out to capture the data in widefield. After waiting for clouds to clear and then sorting out a few initial problems I had little time left for imaging before dawn. I did however manage to capture 7 x 5minute exposures @ f3.2 that I was happy with.

  Click image for a larger view …

Image Data:

After processing the Ha data in Iris, I looked out some of my archive RGB data (20D & 100-400 L f5.6 1.5hrs) of the region and set about combining it. The combine process involved adding some of the Ha to the red channel (thus reinforcing the nebula saturation) and then using the Ha as a luminosity layer. Layer opacity was adjusted by eye before a high pass filtering and final output. {This is based on a method by Don Goldman}. A small version of the completed HaRGB image is shown below.

   Click image for a larger view …

For those of you with Microsoft’s Worldwide Telescope, click here to load and view the region.

About this region:

Cygnus lies right across the Milky Way, it contains both large clouds of ionised hydrogen & dark regions of interstellar dust. These two phenomena combine to give us the beautiful shapes and patterns seen above. The nebulae are thought to be about 1900 light years distant. To read more about these nebulae try the articles on the Wiki or on Britannica.