Picture of the Month - September 2020 - WR 134

A special and world-first photo of the rarely imaged nebulosity around WR 134

A wonderful and special astrophotography image each month by Hungarian astrophotographers.

Wolf-Rayet 134 is a special star, which formed a very rare phenomenon around itself, a Wolf-Rayet Nebula. It lies in the constellation Cygnus, not far from Its famous relative NGC6888, the Crescent Nebula. This rarely imaged object is extremely difficult to capture. The photo chosen as image of the month is unique not just in Hungary but also worldwide, because it shows off this wonderful phenomenon like no one before it. But we will let the photographer, Péter Csordás talk about his image:

I've discovered the Nebula around WR134 fairly recently, when browsing wide angle images of the constellation Cygnus. A web search revealed immediately that among the few results, there are hardly any real deep images, even though the object is very exciting. The thrown-off outer shell of Wolf-Rayet stars can form some interesting shapes of nebulae as the lumps of matter, shed off at different times collide with each other and nearby nebulae. For example, It’s famous neighbor within a couple degrees, the crescent nebula.  

I set showcasing the faint shape sticking out towards the south, barely visible on reference images as my goal. The nebula really prevails with an OIII filter, so I tried to collect enough exposure with it, in good quality, strictly under moonless skies. During processing I myself were surprised, that the structure is clearly shaped like a circle, or more like a sphere imagining it in 3D and the fainter parts also show some defined, thread-shaped detail. The image turned out to be a Ha-OIII-RGB composite, while accentuating the narrowband I also tried to save as much as possible from the RGB color, including star colors and dark nebulae to make the image more natural.

It was an interesting experience furthermore, that I started imaging this subject with the ASI1600MM camera, but since I had never before imaged narrowband with a CMOS camera, I made a comparison with my trusty AtikOne6 CCD. Unfortunately, I concluded that these CMOS cameras although more and more popular, cheaper and they are excellent for RGB, when looking at narrowband they don’t produce the same quality as a CCD. On a longer exposure the noise from hot pixels and amp glow seemed to be too excessive, and even higher gain didn’t yield a better SNR than my other camera. Naturally it isn’t impossible to work with it, with enough exposure and good calibration I am sure It would have been successful as well, but since I already installed it, I continued with the Atik, and haven’t used the multiple hours of exposure from the ASI.

This is then, how the photo, that not only amazed the image of the month jury, but also the international astrophotography community. The picture became Image of The Day on the largest astrophotography sharing website, Astrobin.