Valentines Day this year saw the start of another series of visible passes from the UK of the International Space Station, which if timed correctly can provide a nice photo opportunity. Lot’s of satellites are routinely visible from Earth but with sheer size of the ISS makes it a worthwhile subject to hunt down.
When it’s visible essentially what you will see if a very bright dot in the sky moving at a fair pace. You won’t confuse it with aircraft as it doesn’t have any flashing lights, it’s a steady white light similar to a bright star moving across the sky. For it to be visible though you need to catch it when it’s not in the Earth’s shadow as the light is provided by the sun reflecting off its surfaces, if it’s out of reach of the sun, you won’t see it.
Predicting where it will pass is pretty easy if you have access to app’s such as Star Walk on the iPhone, or any similar night sky tracker that show’s satellite positions. With Star Walk you can locate the ISS and then fast forward time to see where it will be at any given time, what it won’t show you though is if it will be visible from your location or not.
To determine visibility you’ll need the Heavens Above website. Simply select your location in the configuration settings and then look at the ISS predictions for the next 10 days, this will show you all the visible passes. Remember to deduct 1hr from the time for current UK time. Also check how long it will be visible for, it might be only a handful of seconds, it might be minutes depending on the position of the Earth shadow. The lower the mag value, the brighter the pass will be.
Armed with this information, what you need now is a nice dark location with a good view to the West and South and a clear sky, the ISS will arrive from the West travelling east. On a shorter visible pass your best bet is to setup the camera looking approx South-West, if you have access to the Star Walk app, try to see which easily identifiable star constellation it will pass near, that will help you decide where to point the camera. At the moment, it’s passing very close to Orion, one of the easier constellations to find.
Usual star photography settings apply, you want to be (in a very dark location) around ISO1600, lens as wide as you can get it (f3.5-4.5 is fine) and exposure should be enough so the sky looks light but not blown out, you can darken the sky back down again in post processing but for now we want to be sure we’re picking up as much image data on the stars as we can. In more light polluted area’s you’ll have to drop the ISO to maybe around ISO400 to stop the image blowing out.
After that it’s a case of watch and wait. Take a few test exposures so you know what field of view you’re going to capture in the shot, as you see the ISS (it’ll be fairly obvious) approach your field of view, hit the shutter (with a remote obviously) and keep taking exposures until it’s gone or you’re sure it’s out your field of view.
You can always combine multiple exposures in a programme such as Startrails.exe or StarStax to get a full trail of the ISS over the frame later.
This is an example of pointing the camera to much to the South and not enough to the South West, the little streak on the bottom right is the ISS but despite having watched it for a good 20s before it went into the shot it then went into the Earth shadow and that was it, gone for the night! There are loads of opportunities though over the next few days so if you don’t get it first time, try, try and try again!
If you get a dark enough location you might also be lucky enough to get some decent star shots in general just now, with the moon well out the way of the early evening night sky the stars are nice and bright to the point it’s even possible to pick out (faintly) the Milky Way just a few miles outside light polluted Edinburgh.