Updated: Oct 28, 2019
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 specific or a DSLR camera.
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.
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)
LOCATING 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 accross
Wolf-Rayet star gives NGC 2359 its glow
Similar to the Bubble Nebula, but more complex
SINGLE SHOT & PROCESSING OF THOR'S HELMET
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!
Thor's Helmet is one of our favorite nebulae (if not THE favorite?) and we really cannot wait until getting a great final image of it. Hopefully we will be able to do it this year and update this post soon :)
Antoine & Dalia Grelin
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