Urban Orion


Urban Nightscape – Orion over Calgary

On a very clear night, Orion shines over the skyline of Calgary.

As I live in the country, it’s not often I shoot the stars from urban sites, and certainly not from downtown Calgary. But the combination of a clear night and a speaking commitment in Calgary provided a chance to see what was possible under ideal conditions.

The lead image is real – I did not paste an image of the sky taken at some other time or place over the skyline image.

However, the sky image is a longer exposure (10 seconds) than the ground (3 seconds) in order to bring out the stars better, while keeping the city lights under control with no overexposure. So it is sort of a high dynamic range blend.

The other factor that helped reveal stars as faint as shown here (fainter than what the naked eye can see) is the use of a light pollution reduction filter (a NISI Natural Night filter) to penetrate the yellow sky glow and provide a more pleasing colour to the sky.

Earlier in the night, during twilight when urban light pollution is not so much of an issue, I shot the waxing crescent Moon setting over the skyline.

Crresent Moon over Calgary

This is a panorama image made from high dynamic range blends of various exposures, to again accommodate the large range in brightness in the scene. But I did not use the NISI filter here.

These images demonstrate how you can get fine astronomy images even from urban sites, with planning and timing.

To that end, I used my favourite app, The Photographer’s Ephemeris, to determine where the sky elements would be as seen from a couple of viewpoints over the city that I’ve used in the past.

The blue spheres in the left image of TPE in its Night mode represent the Milky Way. That chart also shows the direction toward Orion over the city core.

The right image of TPE in its Day mode shows the position of the Moon at 6 pm that evening, again showing it to the left of the urban core.

Other apps are capable of providing the same information, but I like TPE for its ease of use.

Clear skies!

— Alan, January 20, 2018 / © 2018 Alan Dyer / AmazingSky.com