Could be, I didn't take any H alpha data. Or maybe if it is strong in
NIII it is also strong in NII which is picked up by a 5 nm H alpha
filter. You need a 3 nm filter to separate the two. Might be the
nebula is more NII than H alpha. I don't have a 3 nm filter to find
out. That's not in the budget for now.

Rick


On 4/24/2010 1:02 PM, Glen Youman wrote:
Did a Q&D image of sh2-80 in 2005 - not as deep as your's. I had the
impression from my image that there is a lot of Halpha in the spectrum
of the star.

Simbad shows a redshift of .000647 which doesn't make sense.




On Fri, 23 Apr 2010 21:11:06 -0500, Rick
wrote:

Sh2-80 goes by so many designations I don't know which to use (SIMBAD
lists 30!). But since I've been imaging some small Sharpless objects
I'll use that. It is an 11th magnitude Wolf Rayet star, WR 124
(Merrill's Star, for Paul W. Merrill who specialized in spectroscopy of
strange stars -- he also has a lunar crater named for him) surrounded
by a nitrogen rich bubble. Some catalogs, well many, consider it a
planetary nebula but it is really a Wolf Rayet bubble much like NGC
6888, the Crescent Nebula, in Cygnus. Thor's Helmet is another such
bubble. The star is classed as spectral type WN 7 or 8 depending on who
you listen to. The N means it is nitrogen rich, the 7 and or 8 means
the NIII line is stronger than the NIV line. NIV is weaker in WN8 than
WN7 in case you were wondering.

I can't find much on this guy, no distance estimate so no size estimate,
no age info etc. Just a ton of names for the star and nebula, many
being incorrect PN designations such as M 1-67 and G050.1+03.3.

Seeing was poor this night. No H alpha was used. I had several nasty
satellites go through the color data and one in the luminosity data.
With only 4 frames noise rejection didn't work well, my algorithm needs
at least 6 to be of lower noise than a simple add or average combine.
So it was left in rather than clone out a bunch of stars along with the
satellite. I did remove the color ones as they didn't harm many stars.
Just too many stars to clone it out of the L image. This bubble must
not contain any OIII emission. That falls partly in my green and blue
filters which overlap a tad at the OIII line. Yet the green filter
showed no hint of the nebula while the blue showed the right intensity
for H beta emission without any OIII contribution. Maybe someone with
an OIII filter can verify this.

Cropped image enlarged to 0.5" per pixel for those with small dot pitch
monitors.

14" LX200R @ f/10, L=4x10', RGB-2x10'x3, STL-11000XM, Paramount ME

Rick


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Correct domain name is arvig and it is net not com. Prefix is correct.
Third character is a zero rather than a capital "Oh".