Our systems are rather different. Robin understands optics much better than I do so hopefully he'll chime in if I say something stupid.
I think it might be helpful if we zoom in on these spectra. Here's my contribution. (In RSpec one can make the data points visible)
I think I've made some resolution of the emissions of [O III] at 495.9 nm and 500.7 nm. This affords a resolving power of ~ 100 at this wavelength given by the formula 495.9/(500.7-495.9).
I'm not sure your system affords such resolution but I'd be happy to see the zoom. My H-beta peak gets down pretty close to the baseline at 491 nm.
The same calculation suggests that a resolving power of ~ 300 would be required to resolve H-alpha and [N II], which I clearly don't have.
I think that in a slitless system, in addition to grating line spacing and distance between grating and camera, both the telescope aperture and also the focal ratio affect resolution because of their effect on spot size. Seeing also plays a great role. I have great seeing here in Florida, but this spectrum was taken in Canada. I think that both smaller aperture and faster focal ratio will afford smaller spot sizes and therefore the potential for greater resolution. Camera pixel size is also important; mine are 2.9 um, yours are 5.19 um.
Another difference between our systems, that I think is relevant here, is light gathering power of the telescope. In this I think your telescope is superior, but that means you will also have more field stars superimposed on the spectrum. Comparing our two spectra, I don't have much confidence in any peak that I can't see in BOTH spectra. I think this is a limitation of slitless spectroscopy. Unfortunately, most other spectra (like this) will be from slit systems, which will sample only a portion of the nebula that usually doesn't include the central star. I haven't found the spectrum of this central star.
Edited by Organic Astrochemist, 25 October 2019 - 10:19 PM.