Just one this week. Sunset over Launiupoko, HI.
Theme: Deep Space
This is a photograph I recently took of the Andromeda Galaxy. At 2.5 million light-years away from the earth, Andromeda is one of the
closest galaxies to us. It is actually fairly large in the night sky, but it is very dim.
I did NOT take this with a telescope. I actually took this image with my normal camera and one of my normal camera lenses (Nikon 300mm f2.8). I was able to take this photograph by using a special camera tracking gizmo that I designed and made and by using the same image processing technique that NASA uses for processing Hubble images.
—Nerdy Astronomy Details—
There are actually three separate galaxies in this image. The small light smudge below Andromeda is a small galaxy called M110. M110 is 2.9 million light-years away from earth. The fuzzy looking “star” on the upper edge of Andromeda is another small galaxy called M32. M32 is 2.65 million light-years away from earth. All the smaller stars in the image are stars in our galaxy between us and Andromeda. They are much closer to us and are probably only 50-70 thousand light-years away from earth.
—Nerdy Image Details—
Taking the Image:
I’m always looking to try out new types of photography and for the last few months I have worked to develop a method for taking images of deep space objects without a telescope. I took this picture using a sky tracker widget that I designed and built specifically for this. If you would like to see a photo of my sky tracker widget, let me know.
The tracker is completely mechanical and simply uses a carefully made gearbox and lead screw to move the camera at the same rate that the earth rotates. The tracker will consistently take images with no noticeable blurring for several minutes.
Processing the Image:
To get fine image detail, I have found that most deep space objects photographed with normal camera equipment require exposure times of several hours and not just several minutes. Although, the widget that I made will track the sky for about 4 hours unattended, for a number of unavoidable photographic and astronomical reasons, it is far better to take a large number of short exposure images and “stack” them on top of each other afterwards. It is also not required that all the “stacked” images be completely identical. To achieve the highest detail image possible, the images can be taken under different conditions (and even on several different nights). This is the same basic technique that NASA uses for processing Hubble images. For this image of Andromeda I took about 840 images for a combined exposure time of about 7 hours.