The NHZ is happy to present the first full colour image of SNR G116.6−26.1 - a ginormous high latitude Supernova remnant in the constellation of Andromeda. 

This is a very special SNR due to several aspects; first of all this is a high-latitude SNR, meaning it is far away from the galactic center. Note that only 10% of known SNRs are high-latitude ones (i.e >15° Gal. lat). Adding to this is the shear size of this thing - the “main part” measures some 3x4° in extension which is huge for SNRs. Note that there seems to be Oiii extending off frame which would mean it stretches over 6°. 

Interestingly enough this SNR lies relatively close to M31 which is part of the reason why we chose to image it - find a possible correlation between the Oiii arc and the SNR. Note that this was very unlikely from the start, but never say never. For anyone interested I recommend reading this paper (https://arxiv.org/pdf/2307.06308.pdf) which investigated possible connections and found none.

Imaging this SNR proved to be a big challenge due to it being so faint - as you can see we collected 55h Ha and 84h Oiii. Not only was this data taken with fast FSQ 106 f/3.6 and f/3 scopes, but also from dark skies (B1,2 and 3) - in the end the signal was still super weak and we had to really push the data to get it to where we wanted. In fact, the brightness of the Oiii filaments is in the order of magnitude of that of the Oiii arc near M31.
For more in-detail spectral analysis I recommend reading this paper about the SNR (https://academic.oup.com/mnras/article/515/1/339/6608270) which, as far as we know is the only paper talking about this SNR. It also includes in-depth documentation of the SNR and interesting measurements. Note that the SNR also has Sii emissions - for this image we decided to go HOO though as we wanted to maximise SNR for Ha and Oiii and including Sii would have taken integration time away from Ha Oiii. 
As a side note, the morphology of the SNR reminded us strongly of that of another SNR, SNR G70.0-21.5  (https://www.astrobin.com/lhhcr5/). That SNR is also super big and a high-latitude one - adding to that is the similarity in morphology which we find very interesting. In some way you could say these two are siblings :-) 

I also want to thank Sendhil, Tarun, and Patrick who dedicated some serious imaging time into this project; Without their commitment we would not have been able to pull this image together and overcome the challenges of this super faint target.
Also, a big thank you to our editors Steeve and William who pulled together the two amazing edits at hand - dealing with this data sure wasn’t easy but they managed to get the best out of it.
Finally,  thank you to Sakib who first mentioned the SNR which lead to us starting the project. 


Thanks for viewing and reading - we hope you enjoy our work! 
- Tim Schaeffer and NHZ team