3 replies to this topic

[SNH]

Hi all,

Back in September, I did a bunch of research into obscure and/or recently discovered supernova remnants with the intention of tackling the brightest of them this autumn. That's when I learned of one in southwest Cassiopeia, along its border with Lacerta, that was first "published" on AstroBin less than a year ago.

 

Nicknamed the "Nereides Nebula" (G 107.5-005.2) by its discoverers, it's currently the SNR with the largest angular size ever discovered by amateur astronomers and is the subject of at least two papers (Fesen et al 2024, Araya 2024) in the last 12 months!

 

So, I figured by the strength of the O III emission I had a good shot with a friend's 36-inch. Here are my notes:

 

 

Oct 4th / 36” / Nereides (G107.5-05.2) SNR in Cassiopeia. Using Lacerta’s brightest stars to guide me to it, I found that at 150x and with an O-III filter there was a surprisingly easy area visible as a softly glowing strip visible on the NW edge of the SNR. I failed to see any of its southern wall and did not attempt the northeast "corner".

 

Oct 5th / 36” / Nereides (G107.5-05.2) SNR in Cassiopeia. Using Lacerta’s brightest stars to guide me to it, I once again found visible the same part of the SNR that I had last evening. This time though, I searched the NE “corner” of the SNR and found a triangular section visible at 150x with the O-III filter.

 

Oct 7th / 16” / Both pieces that I had previously seen with the 36-inch are also visible at 100x with O-III in 16-inch f/4.5 dob. Not quite as distinct, but I'm sure it will be seen with less under better skies.

 

 

Here is the original chart that I drew up and used at the eyepiece. Note that I did NOT use an actual photograph to not introduce much chance of false positives.

 

 

And here is a low-quality copy of the O III image taken by the team who discovered the Nereides SNR and the parts that I've seen marked.

 

I expect in the next year or two a lot of folks will have seen this one. So, enjoy, and hats off to Marcel Drechsler, Bray Falls, Nicolas Martino, and Yann Sainty for finding and imaging it! We visual folks owe you big time!!

 

Scott H.

[Keith Rivich]

That's really cool Scott! 

 

I'm going to be lazy here...do you have the center coordinates for the strips you observed?

[SNH]

The one in the northwest is about 23:02:20 +55:49:15

 

The one in the northeast is about 23:11:14 +55:12:09

[j.gardavsky]

Hello Scott,

 

and congratulations on your sucessful observing report of the Nereides SNR Nebula.

This is a great news for me!!!

 

I have made a preliminary location and observation of this SNR on June, 8th, and the next observation on August, 16th, 2024: 15x85 BA8 binoculars, OIII filters 12nm and 10nm, H-Beta 5.5nm

 

The OIII filters have revealed a nearly complete shell, and resolved the pairs of filaments on the E and W side of the shell. And initially this has been a problem for me, as I did not expect pairs of the filaments.

 

Even for the binoculars, this SNR is really big, and it has been scanning the skies east to west, north to south, and along the diagonals.

 

Clear skies,

Jiri