SII-Rich Areas of the Northern Sky

Hello everyone,

I'm in need to test a SII filter (first time ever) and I'd need to capture some nebula which is both rich (and bright) in SII and poor in Ha and because of my northern latitude it would be best it be at least at +20deg N. Visible for most part of the night in, let's say, the next couple of months (British foul weather permitting). FOV about 1 degree square. All suggestions welcome.

Thanks!

The Rosette is a good one, +5, but the Ha is really heavy. The California is also good, about equal in Ha and SII if +36 isn't too high.
This is a single 15 min with a 3nm and a 16803. These are big, forgot you're looking for about 1 deg.

NGC1499 / California_2020 (Bob Lockwood) - AstroBin

IC 1805 (Heart Nebula)

You can look for predominantly blue areas here: https://simg.de/nebulae3/dr0_2/

I went here ( Overview image of DR0.2 of Northern Sky Narrowband Survey in [SII], H-alpha, and [OIII]) and the most likely candidates (for my location) are the following:

LBN 560-551 SI-2

SNR G132.7 +1.3

HDW2

And later in the night:

SH2-221

SH2-216

Obviously NGC1499 and IC1396 are also rich in SII but unfortunately very strong in Ha too. I have no idea how strong is SII in the listed above nebulae. Maybe someone managed to captures some of them in SII?

andrea tasselli · Oct 12, 2025, 08:17 PM
Maybe someone managed to captures some of them in SII?

IC 1396 in Ha and Sii. Sulfur isn’t brighter than the Ha here by any margin.

📷 image.png

Aformentioned IC 1805 (Melotte 15) has an extremely bright Sulfur region, and while the Ha is equally as bright, it showcases a substantially different structure. Hope it helps a bit

📷 Screenshot 2025-10-12 165812.png

These targets hardly fall into the realm of what you’re asking for. I’m not sure they exist.

Thanks guys for the suggestions. I'll try Melotte 15 as it seems the most promising and hopefully enough to differentiate the Ha from the SII. I'll try odd ones when time and weather permits.

This website isn’t super up to date, but it provides an overview of the relative contribution of S/H/O in a fairly large catalogue of popular nebulae! https://www.galactic-hunter.com/post/filter-expectations

It’s a great resource that I have used many times to double check that my S+O filter was not defective 😅

Thanks everyone. I was able to learn about two resources that I was not aware of. Im absolutely sure these will help me capture targets based on what I am actually trying to/expecting to obtain in my data acquisition.

Marco Montella · Oct 13, 2025 at 11:46 AM
https://www.galactic-hunter.com/post/filter-expectations
Rick Krejci · Oct 12, 2025 at 07:54 PM
https://simg.de/nebulae3/dr0_2/

“Unless you need rain, Clear Skies”. Pat Prokop’s Heavenly Backyard Astronomy

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