At one point in time we’ve heard the saying that we are all made of star dust. Therefore, our home , the Milky Way, filled with 250 billion stars should be rather dusty. Right? Well it is, and one famous dust lane that we often see even has a name: The Great Rift.
Say that you are out camping this summer, and you spot the MilkyWay as you are amazed how many stars you can see when away from the city. You remember you have your camera and decide to setup for some long exposure shots to capture all this beauty (lets go for 20 seconds at ISO 3200 17mm F4.0) pointing to the constellation Cygnus. A bit of processing and you should get something like this.
Not bad! Lots of stars… a brighter band where the Milky Way arm of the galaxy is located and some darker spots at various places. Those darker areas are gigantic dusk clouds between Earth and the arms of our spiral galaxy that obscure the background stars. If only there was a way to remove all those stars, you could better see these dark areas.
And there is a way to remove stars! It’s called StarNet++, takes a load of CPU power and works like magic to remove stars from photos. Abracadabra!
Behold! The Great Rift! Well actually just a portion of it. With the camera setup I get at most a 70deg field of view of the sky. Nevertheless, the finer details of these “dark nebula” can be appreciated.
Stripping the stars from an photo does have some advantages: it allows the manipulation of the background “glow” and dusk lanes without concern to what happens to the foreground stars. The resulting image (a blend of both the starless and original image) had improved definition of the Milky Way, higher contrast and softer stars that improve the visual appeal.
While there are plenty of stars above us, what defines a nice Milky Way shots is the delicate dance of light and darkness between the billions of stars and the obscuring dust clouds.
Photo Info: Canon 80D 13 x 20 sec (4min 20sec integration time) 17mm F4.0 ISO3200 Deep Sky Stacker IRIS for background gradient removal and color adjustment StarNet++ GIMP for final processing
A few weeks ago after taking some photos of Jupiter, I changed my setup to do some long exposures on an easy target: a globular cluster. Unfortunately I forgot to note down the name of what I had photographed! So a few weeks later when I found the time to process the images I was at a loss to identify what Messier object it was. However, after an evening of matching up stars surrounding the cluster and I was able to correctly identify it as Messier 3.
Globular Cluster – Messier 3 (Benoit Guertin)
The above was taken with my Skywatcher 80ED and Canon 80D. It is a stack of 27 x 10sec exposures at ISO3200 on an unguided and roughly aligned mount.
Looking at my archives I found that I had imaged M3 about 10 years ago with the same telescope, so I decided to align both old and new image and see if anything would stand out. And to my surprise, spotted one star that appeared to have shifted. To help identify the star I colorized one of the photos and subtracted from the other (done in GIMP). All the stars within the field of view lined up except this one; the two colored spots are not aligned!
In one of my previous post I mentioned how Messier 44, the Beehive Cluster, would be an easy find the evening of April 22-23, so even if I took this photo on the 21st, the same evening that I took a photo of the Moon, all I needed was to moved a few degrees north after observing the Mooon to image this large open cluster.
Messier 44 – Beehive Cluster. Benoit Guertin – taken with Skywatcher 80ED and Canon 80D
Photos of open clusters with small refractors always lack the diffraction spikes that really make the stars stand out. So a little photo editing did the trick to spice up the image.
Canon 80D ISO 3200
Stacked 22 x 10sec
Looking at the sky at night from your backyard you’ll probably be able to see about 50 stars, more if you are away from the city. So how many do you think is in the frame below?
Portion of the Milky Way near Vulpecula.
Taking a 200 x 200 pixel sample in the middle I counted 155 stars. Hence extrapolated to the entire picture comes to 38,000 stars for this 18 x 10 degree portion of the sky. OK I cheated in taking a picture of a portion of the Milky Way… Nevertheless that is a rather small fraction of the 300 billion stars estimated within our own Milky Way.
Bonus if you can spot the meteor! Showed up in a single 30sec frame, which I added separately in post processing, else it would have been eliminated from the final image as it’s a random event and I always use a sigma distribution for my stacking. Hint: it’s located just above open cluster CR399, also known as Brocchi’s Cluster.
Welcome to a journey into our Universe with Dr Dave, amateur astronomer and astrophotographer for over 40 years. Astro-imaging, image processing, space science, solar astronomy and public outreach are some of the stops in this journey!