Back in 2010 I captured a wide-field mosaic of the Rho Ophiuchus area that overtime became one of my "signature" deep sky images (you can see it here
tinyurl.com/rhoopfb )... I captured that image with broadband filters - in plain language, the colors of the rainbow. A few days ago, checking some data and sky surveys, I noticed that in this area there were also some very clearly delimited nebulosity emitting light in the very narrow Hydrogen Alpha band that however were not showing in my original image - or in many of other images of this area. So, during the last few days I spent the last hours of the night capturing H-Alpha data in this area. I integrated this data with the previous image and voila! Nebulosity that was invisible in my previous image, suddenly appeared.
The "new" emission nebulosity is most apparent, as you can see, in the left area of the image, particularly around the stars Delta Scorpii (SH2-7) and Pi Scorpii (SH2-1). Interesting, isn't it?
Check the entry on my page for a peek at the before/after versions:
www.deepskycolors.com/archivo/2014/03/18/the-Surprise-Neb...
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