Special thanks to @Marcel Drechsler for this incredible banner painting! 

HADES - The God of the Underworld
As the third gigantic supernova remnant discovered by amateurs, we thought it would be fitting to keep the Greek naming convention and name this nebula after the Greek God of the Underworld, Hades. Hades was the eldest son of Chronus and Rhea. He and his brothers, Zeus and Poseidon defeated the Titans, and claimed rulership over the Cosmos. Zeus received the sky, Poseidon the Sea, and Hades the underworld. Hades is typically portrayed wearing his helm, and with his three-headed dog Cerberus at his side. Since this supernova is extremely deep in the southern hemisphere, we thought this functioned well as an allegory for the underworld in astronomy. The large twin filaments inside this nebula also resembled Hades' helm. And so the name stuck! 

Our Team
Aygen Erkaslan - Daniel Stern - Bray Falls - Rob Fesen

The Discovery of SNR G288.2+5.6
The discovery of this supernova remnant happened independently with both Bray and Aygen, in the same exact way! 

Aygen:

As I was surveying the night sky, something unusual caught my attention: an unexpected O III filament emerging amidst an ocean of Ha emissions. Intrigued by this anomaly, I decided to delve deeper into my research, dedicating significant time to collecting O III data in the region. The more I observed, the more captivating the phenomenon became, revealing intricate details and patterns that fueled my curiosity and furthered my understanding of the celestial landscape.

Bray: 

My first trace of this SNR came from my very first test image captured from my remote observatory in Namibia. I was taking photos of the Carina Nebula centered in my frame last year, and there were a couple of interesting things to note in the test photo, one of which was the Blue Cresent in Carina. This year when Carina came back around, I pitched the idea as a potential target to Daniel, who began to collect images from his scope in Chile. 

The Collaboration

While discussing objects with colleagues, we learned that all of us were working on the same object at the same time, and so we decided to join forces and mix data sets for a collaborative image. Aygen had a very wide data set captured from his Epsilon, and Daniel had his data with a closer composition of the main filament.

Both datasets proved to be very useful for the finished photograph, because when combining the data sets, Aygen's wider FOV revealed the presence of a very extended Oiii shell that is extremely faint. It likely continues onwards outside of our framing, but it would be prohibitively faint to mosaic and photograph. Daniel's dataset helped to boost the signal of the very interesting central filament cluster, which may appear bright in this image but it is very faint. 

The capturing of the image happened from two observatories in central Chile, Deep Sky Chile, and Obstech Observatory. Both are located along the Rio Hurtado valley which is an area famous for astronomy. Nearby both observatories you can find Gemini South, SOAR, Cerro Tololo, and soon the Rubin LSST observatory. The dark skies provided by this part of the world really helped to make this image possible! 

Both Aygen and Daniel were incredibly patient, and dumped a staggering 240 hours of total exposure time into this object. For nebulae like this, every second of exposure counts, and they certainly delivered! 

The Nature of the Object

While we don't have a proper spectrum of the object, the morphology of the nebula is very telling of its nature. The presence of extremely fine H-alpha and Oiii filaments are a smoking gun which can be seen in dozens of other SNRs in the night sky. Not to mention, the extensive diffuse Oiii bubble is of such a large size that we would only expect to see it in an SNR. 

It is very useful when studying SNRs to examine them in other wavelengths, like the radio or UV. For this remnant, it sits outside of the UV surveys, and it is far too radio-faint to detect. This also offers an explanation as to why this nebula has not been noticed before, it simply required deep Oiii imagery to become obvious. 

The brightest portion of the SNR creates an amazing composition, which is a chaotic mix of dark nebula, bright H-alpha emission, and many fine twisted filaments. This small portion is definitely worth a follow-up with a bigger telescope.



Where is it?
The Hades SNR sits on the border of Vela and Centaurus, close to the famous Carina Nebula. The surrounding area is full of quite bright H-alpha clouds, and the SNR bubble itself is partially hidden by the overwhelming light of these clouds. If we draw an imaginary bubble following the radius of the SNR's curve, we get an approximate bubble diameter of around 4.5 degrees. We don't know if the SNR actually continues around this circular path, but given the amount of deep narrowband imagery immediately around the Carina Nebula, it is not likely it forms a complete bubble because we would see it in other images. 



The Research and Scientific Naming
When we encountered this object, we made sure to cross-reference Green's Catalog of Galactic SNRs to examine if this object was a known SNR. Our search turned up nothing, and without a trace of its existence in any professional survey, this was a great sign. We contacted Dr. Robert Fesen about verification of the object, and he confirmed this was most likely an unknown SNR! When a supernova remnant has an obvious center, we take the galactic coordinates of the bubble center to be the name. In this case with no obvious center to the bubble, we based the name G288.2+5.6 to on the galactic coordinates of the brightest Oiii filament from which the object was discovered. 

Unexpected Guests
Inside of Aygen's data, two very interesting unknown nebulae have popped up, and both of these will be followed up on in the future:

The Processing
Me, Aygen, and Daniel all took a stab at processing the mixed data sets. Each had their slight variances and aesthetic qualities, and I blended each of our versions in order to try and retain the aesthetic qualities of each. This data set was quite a difficult one to work with, because of the extreme star density, bright Ha clouds, and extremely faint Oiii. It takes careful work to balance all of these components with wildly different surface brightness, all in an extremely dense star field. 

We hope you all enjoy this work, and we hope it inspires you to go out and explore the night sky!