Note - 2 days ago I posted my RASA image of this object. The mouseover here compares both images - this one taken with the EdgeHD 11 (2800 mm fl, image scale of 0.56 "/pix), and the mouseover taken with the RASA 11 (620 mm focal length, image scale of 1.25"/pix). Both scopes are 11" diameter, both images used the same ASI6200 camera, and both images have nearly the same integration time. Although I used the same processing tools, I did not make an effort to process them in exactly the same way and so any effort to draw conclusions from this comparison should be tempered by that. For each image, I simply went down a processing path which led me to an image with which I was satisfied. The comparison makes sense to me, with the RASA resulting in more signal, better illumination of the faint outer region, larger stars, and less detail.
I bought the RASA last year primarily to image large faint nebula. I did not intend to use it for smaller bright targets like this one. But now I am having fun imaging a variety of targets with the RASA setup, even though I will continue mainly using the EdgeHD 11 for targets of this size. *****************************
This object, also known as Sharpless 2-298 and Gum 4, is an emission nebula located 12,000 light years away in the constellation of Canis Major at a declination of -13 degrees. The full extent of the nebula spans about 25 arc-minutes in our apparent view, which corresponds to a width of 90 light years.
The central star here is the Wolf-Rayet star WR7, the bright star seen near the center of the bubble. These are massive stars which have high temperatures and which are highly luminous. They also have a high rate of mass loss as they expel outer layers towards the end of their lives. These stars result in some of the prettiest nebulae in the universe. My Astrobin Collection of Wolf-Rayet nebulae can be seen
here.
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