Urban Imaging

Schedule doesn’t always allow for a trip to dark skies so sometimes we just have to make due with urban imaging from the driveway. Here is a daylight view of my urban imaging environment.

Like a lot of urban sites I’ve got a @#!%$ LED street light right across the street. Here’s a night time view, as you can see there is light pollution to spare.

Around 8PM a friend and I set  up scopes in my driveway and since the tree in my front yard is just starting to have its leaves pop out it wasn’t stopping much of the glare from the LED monster across the street. With the scopes set up and aligned we started imaging. My first target for the evening was Leo1, a very faint satellite galaxy of the Milky Way. This is one of the targets on my imaging challenge bucket list. Not for its low surface brightness, but because it should be resolvable to stars with my equipment. When I started in this hobby well over 20 years ago I decided that I was going to resolve Sirius B, image deep sky objects in another galaxy and resolve stars outside the Milky Way. I was new to the hobby and figured that it shouldn’t take too long once I figured out how to focus the camera. About three years ago I managed to image deep sky objects in M33. A few months ago I managed to catch Sirius B using my latest setup a SkyWatcher Esprit 120 with a Canon 60Da DSLR.

After capturing 80 minutes of data on Leo1 I moved the scope to my next target, M108 and the Owl. I figured I’d go for a bright target in case the Leo1 effort didn’t pan out. Processing the Leo1 shot provided to be a challenge. The light pollution proved to be a limiting factor in how far I could push the stretch. After a few false starts I ended up with this image.

Leo1 is the faint blue fuzz in the center of the frame. For a better view where you can use your browser to zoom in and have a better look visit my web page on this object.

M108 and the Owl Nebula was much easier, but more time consuming, to process. My usual technique requires masked stretches and split star processing, but for this image split star processing really wasn’t necessary so I simply used starless masks to keep the background under control.

Zooming in on M108 you can see that it is possible to get lots of detail even under light polluted skies.

Even the Owl Nebula turned out reasonably well, given that it really needs more exposure and a longer focal length.

With these results I may try urban imaging more often. There are several mosaics to tackle that may lend themselves to brighter urban skies.


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