CTSS-3 (Cappellaro Turatto Salvadori Sabbadin 3) or PN G046.8+03.8 is a large, late stage planetary nebula located in Aquila. Even though it was entered in the Sharpless catalog as Sh2-78 in 1959, it was not until 1990 it was categorized as a PN, when an Italian team used a technique comparing the Palomar Observatory Sky Survey plate used by Sharpless with a new infrared survey plate, also from Palomar. The original publication can be found
here.
CTSS-3 is reported to be at a distance of about 2200 light years and to have a diameter of about 12 arcmin. However, in this image it is evident that besides its intense ”boxy” inner structure it also has a weaker, previously unknown outer structure, extending at least 20 arcmin, giving it an elongated, three-dimensional or moving appearance.
The Ha signal is stronger than the Oiii and spectroscopy has indicated a very strong Nii emission, as is shown in the diagram below, taken from the publication referenced above.
Ra : 19:3:53
Dec : 14:19:45
17h Ha
16h Oiii
3*1h RGB
All exposures are unguided 120s at f/2 and bin 1x1. HOO palette with RGB stars. Image is cropped.
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