Posts tagged “International Space Station

Preparing to photograph the ISS

I have to say, the International Space Station is an engaging photographic subject. Hundreds of miles above the planet traveling at 17500mph it wouldn’t be the first thing you’d think of nipping out with the camera to capture. However, once you figure out roughly where it’s coming from, what you’re looking for and when it’ll be there it’s almost addictive.

If you happen to be on Twitter try following some of these accounts and you’ll be amazed at how many retweets they send out of images after every visible pass over the UK.

@VirtualAstro
@PeoplesAstro
@NewburyAstro

Planning for the ISS makes a huge difference. The @VirtualAstro twitter account is a good place to start, there’s a wealth of info for every pass from that particular source. The website, http://www.heavens-above.com is also good for working out the directions, altitude and brightness of the ISS for any given pass. The free astro programme, Stellarium for Mac or PC is also very helpful, it’ll show you the exact path the ISS will take and from this you can work out in relation to the planets where it’ll be which makes planning a lot easier. The iPhone app StarWalk also allows you to do this.

Here’s a screen dump from Stellarium and from it you can see the ISS path for tonights pass in relation to Sirius and Mars, two of the easier night sky objects to spot.

This is a screen dump from the iPhone Star Walk, from here you can see the ISS and you can advance the time with the bar on the right to watch the path it’ll take over the sky.

Typically the nearer to sunset the longer the ISS will be visible, approx. an hour to 1.5 hours after sunset you’ll get a very bright pass almost from the western horizon to the east later in the night, it’ll disappear into the earth shadow quicker.

So, with this info in mind the temptation is to sit in the house watching the telly and nip out just as it’s about to pass. I’m guilty of it too. But if you apply a little landscape photography principals to the astro info you can totally change the shot you get.

Photographing just the sky is fine, and even better if you can get something significant in the sky to reference the ISS path, i.e. passing Mars, or Saturn. However, get the land in the shot and you’re starting to tell a story with your shot, you’re showing the whole event. The pass of this object over the scene you’re looking at. So tell me whats better here…

The ISS crossing over my back garden, passing just over Saturn

ISS flies over Saturn 14 April 2012
Or this image taken on the Cammo Estate in Edinburgh

ISS over Cammo Edinburgh

The 2nd image took a stack of planning to get. All the info above plus looking at Google maps to find a location with good views to the west, south and east. The only issue I had with this image was the clouds were obscuring Mars so I couldn’t get a reference for how high the ISS would be in the sky, with hindsight I should have used a wider lens but we can all be great in hindsight can’t we?

Using Star Walk I figured out roughly where on the horizon the ISS was going to emerge from and composed the shot to catch it as quickly as I could as it rose, also keeping in mind I wanted Cammo Tower and the copse on top of the hill in the shot. Ground was kept to the bare minimum required and the sky was the main focus.

The sky was still quite light so I went for a balance to catch the ISS. I used ISO320 and f4.5 and limited the exposures to 10s, this gave a nice balance in the shot but meant enough sensitivity to get the light from the ISS.

In the end I got 12 frames of 10s each until the ISS left the field of view, being an early pass I had time to recompose and get another few frames before it disappeared.

The 12 raw images I took into ACR and processed them all exactly the same and saved as jpg files. These 12 jpg’s were loaded into StarStax and blended on lighter mode. This was fine, the ISS trail was night and bright but the cloud movement was nasty and not smooth. To get around this I stacked the 12 images again using the “average” method which gave a much more pleasing image with the clouds but a faint ISS trail. I then blended the first image into this on lighten mode and decreased the exposure until only the bright ISS trail and stars remained. The resulting image was flattened and tweaked in photoshop to produce the final image.

If I were to process again I may patch in the gaps in the trail between the exposures and as a personal preference I would also try to lose the star trails by blending in another image and selectively deleting the trails.

With a location like this though and a nice (nearly clear sky) it’s worth taking time for a few other shots before you back up.

This was a single from from the composite image. Notable objects in the shot are the ISS, Mars, Regulus, Sirius, and Orion.

Mars and ISS over Cammo Tower

In this shot, the ISS can be seen behind the clouds passing just over Saturn and Spica.

Saturn Spica and ISS over Edinburgh

In this final shot taken just after the ISS pass, Venus is nestling on the branches of this particularly creepy tree!

Venus in the spooky tree

A little planning can work wonders, it’s all just about planning and crossing your fingers for the weather to play ball. It won’t work out every night but for that odd one it does you’ll be well pleased you put in the effort.

Get out and look up tonight and for the next few nights before it disappears under the horizon for another few weeks!


Photographing the International Space Station (ISS) from the UK

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!

ISS over the Pentlands

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.

Stars over Harlaw