Tuesday, December 13, 2016

Sh 2-279 Running Man Nebula

Usually overlooked and ignored by stargazers, the running man nebula is a reflection nebula associated with Orion’s giant molecular cloud, a star nursery located at about 1400 light years away from us.

The constellation of Orion is a sea of nebulosities, but the great nebula (M42) always wants to steal the show. It is the not only the brightest nebula in Orion but also in the whole northern Hemisphere. Being so close to M42 is precisely a big disadvantage for Running Man Nebula. It is hard to see the low brightness in its surface while looking at the very bright M42. Anyways, it is better to keep M42 out of the field of view, if one wants to see the Nebulosity in Sh 2-279.

Who said a filter is needed to see this dim, magnitude 7 nebulae? Being a reflection nebula it is more likely it won’t respond well to light pollution filters, UHC, OIII or other kinds of nebulae filters. A dark sky and good transparency are the requirements to catch a glimpse of the nebulosity though.

I am just starting to experiment with dim nebula observation and recently discovered a good trick that will probably work for you all as well. These kind of reflection nebulas are associated with one or more bright stars that are the ones that contribute the light to be reflected in the nebular dust. The problem, at least in the few experiences I have had, is that the star is very bright so one can’t make a difference between the real nebulosity or the star glance. To solve this issue, I compared the nebular area with another area where a star of similar brightness was located. In this case, there is a group of bright stars just above Running Man Nebula, they make the open cluster NGC 1981. I picked some of the stars in that group to make the comparison.

Once I realized something different, I kept comparing the nebular area with the sky background. The nebular glance was very subtle so most of the times (at least from my Bortle 4/5 skies) one can only detect a variation in the tone of the background.

The key here is to compare as many times as necessary and even moving the nebular area in and out the FOV. Once one does it several times, the mind starts to see nebulosity and then the sketch comes in hand. I had found myself imaging stuff, especially when using averted vision (that is the second advice to detect this subtle nebulosities), but I sketch and then compare with sources like Stellarium or photos in the internet. I can see that the more time I spend observing and sketching, the most details I have learned to see and it is not my imagination, but the development of my observing skill.

I did the sketch having a vague idea of where to find the nebula parts. After the sketch was done, I compared it with Stellarium and realized I could see some of the dimmer nebulosities around the stars of 8th (NGC1973) and 9th (NGC1975) magnitude above c Ori and 45 Ori. The brightest part of the nebula (NGC1977) is around and between these last two stars that are also the brightest in the whole sketch. 


As often is said, observing is a learned skill so no matter what, keep trying and it will pay off.




Clear skies,


LG


Edited by Jennifer Steinberg (editor in chief)



No comments:

Post a Comment