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Full Version: Surface brightness of Veil Nebula (West) is 99.9
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Hi Greg,

I just looked at the western part of the veil nebula in the Exposure Calculator and it couldn't estimate an exposure because the surface brightness is listed as 99.9 for the (V), ® and (Total) bands. The mag is listed as 7.0. The (V) band for the eastern portion is 19.2, the (total) is 18.0 and the mag is 7.0. The EC works with the eastern portion OK. The Imaging Project also shows 'Error' for the Exposure Time in the 'Filter' section of the 'Exposure Goals' tab. The "Info and Suggested Settings' box doesn't show the Surface Brightness data so it offers no clue about the source of the 'Error'. A screenshot of the Imaging Project tab is attached showing the 'Error'.

I don't know when the 99.9's entered the database, since I haven't looked at the Veil using the EC in a while. I just saw a nice photo of the Veil on the DPReview Astrophotography page & checked it out. I expect that the Veil will become a popular imaging target this summer.

Phil S.
Hello Phil,

The Veil nebula is a supernova remnant, which is an emission line object, so the surface brightness is only provided for reference. It is not used in the calculations. That said, I see that no emission line strengths are listed on the dialog. That would explain the error that you are getting. I will look into why there is no emission line data.