Updated: a day ago
NGC 2359 is a cloud of interstellar gas that resembles Thor’s Helmet. Although very faint, the colors in the gases really pop when taking long exposures, with both an astrophotography dedicated camera and a DSLR.
This beautiful deep sky object gets its glow from WR7, a massive Wolf-Rayet star that will soon turn into a supernova.
We recommend as many hours as your patience can allow to capture this target. While a total of 4 hours can yield fair results, additional time will give you all the faint gases surrounding NGC 2359. Those are not often seen in amateur photographs but make for a really impressive final image.
Object Designation: NCG 2359
Also known as: Thor's Helmet Nebula
Constellation: Canis Major
Object Type: Emission Nebula
Distance: 11,970 light-years away
Discovered in: 1795
Thor's Helmet Nebula has a truly unique shape! It obviously got its name from the shape of the Marvel superhero Thor's helmet.
Before Thor was even a thing, the nebula was known under a different name: The Duck Nebula. This is why you might find NGC 2359 labeled as "Duck Nebula" instead of "Thor's Helmet Nebula" in some planetarium software like SkySafari.
The name "Thor's Helmet" ended up being the one to stick around the most, and is now what everyone knows this object as! Sorry ducks!
We imaged Thor's Helmet twice. The first time was our very first light with our monochrome camera (the ASI1600MM) which you can see if you scroll further down. The second time was in January 2021 when filming Episode 15 of Galactic Hunter. This time, we used a QHY600M camera and did a bi-color combination.
You can see our final result below!
Telescope: Stellarvue SVX130
Mount: Astro-Physics Mach-1
Guiding: ZWO ASI 290MM Mini
Accessories: Moonlite Nitecrawler focuser
Total Exposure Time: 10.7 hours
Exposure Time per frame: 10 minutes
Filters: Chroma 3nm Ha/Sii/Oiii
Thor's Helmet with the ASI1600MM and 8" Newtonian
The image below was taken during our very first "test night" with our new CMOS camera, the ASI 1600MM. This is an image of just 3 hours of total exposure, and we plan to retake this to achieve a total of 6 hours. Come back here to see the difference between the two!
Camera: ZWO ASI 1600mm Pro Mono
Telescope: Orion 8" Astrograph f/3.9
Mount: Atlas EQ-G motorized Mount
Acquisition: ASI Air
Total Exposure Time: 3 hours
Exposure Time per frame: 3 minutes
Filters: Ha (1 hour) / Sii (1 hour) / Oiii (1 hour)
How to Find Thor's Helmet
Thor's Helmet can be found in the constellation of Canis Major. It is fairly easy to find, because it is very close to the brightest star in the night sky: Sirius. From there, simply travel about 8 degrees northeast in order to find the nebula.
Thor’s Helmet is a faint target that is impossible to spot with the naked eye or binoculars. A telescope of at last 6” is required to spot its nebulosity from an extremely dark site, but do not expect to view something impressive. A 10” telescope will reveal some of the shapes in the gases. If you would like to see more of the nebula, you would need to attach a filter to a high power telescope, and only then will you be able to distinguish the iconic shape of the helmet.
About 30 light-years across
Wolf-Rayet star gives NGC 2359 its glow
Similar to the Bubble Nebula, but more complex
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Single Shot & Processing of Thor's Helmet
Using the ASI1600MM - January 2019
We used three filters to capture Thor's Helmet: Ha, OIII, and SII. Both Ha and OIII gave us impressive single shots (see below for Ha), but SII only showed us a tiny bit of gas.
Single shot of Thor's Helmet with the Hydrogen Alpha filter - 3 minutes at gain 139
The processing was fun, as we decided to do a Hubble Palette workflow. We still have some noise and not enough "orange" in our image, so we really hope adding 3 hours to it will fix that!
Using the QHY600M - January 2021
Wondering what a single 10 minute shot would look like with a better camera and better skills?
On the left below is a 10 minute shot using the OIII filter. On the right is the stack (about 5 hours) image, slightly cropped. Notice how much gas gets revealed thanks to stacking.
Thor's Helmet in OIII. 10 minutes (left) vs. 5 hours (right).
If you are interested in learning how I process all our images, you can download a full PDF "follow along" file that contains 77 pages, a full 1 hour and 45 minutes walkthrough tutorial video, our custom pre-sets and even raw data HERE.
Galactic Hunter Episode 15 - Thor's Helmet
Thor's Helmet is the star of Episode 15! We did our best to make this a fun yet instructive video, and we hope you like it!
You can find the full episode below!
Thor's Helmet is definitely one of our favorite nebulae. It is not a difficult target and can be photographed by beginners quite easily!
Have you captured Thor's Helmet Nebula? Attach your image in the comments and let us know your acquisition details!
Antoine & Dalia Grelin