8/13/2019 Sky at Night 103_How to Observe ISS[1]

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How to

skyatnightmagazine.com

Orbiting almost 400km above the

Earths surface and travelling at

speeds in excess of 27,000km/h

the International Space Station (ISS)

sounds like an impossible target to detect.But, with some careful planning, its

possible to observe and even image the ISS

from the UK.

The space station makes regular passes

over the UK, orbiting at a 51 inclination

from the equator, so there are lots of

opportunities to spot it with the naked

eye, binoculars or a telescope.

Online resourcesThe best way to discover where and when

the ISS will appear in the night sky is by

using an online tool like those featured on

Heavens Above (www.heavens-above.com)

or CalSky (www.calsky.com).

Whichever site you decide to use, its

important you enter your latitude and

longitude as this will be used to calculate

the geometry of the pass.

In the chart at the top right of the page,

Mag (magnitude) refers to the space

labs brightness, Alt. (altitude) refers to

its position above the horizon and Az.

(azimuth) refers to which direction you

should look.Remember, the ISS always moves

from the western horizon to the eastern

horizon when viewed from the UK.

Observing techniquesThe ISS is one of the brightest objects in

the night sky so it is possible to observe it

with the naked eye, however you wont be

able to spot any detail.

Using a telescope or binoculars to

observe the ISS will make it appear far

more brilliant. When it emerges, it will

look about the same size as Jupiter and,with very high magnification, it is possible

to make out some detail.

OBSERVE THE ISS

If you decide to use a scope it will need

to be freely mounted in order for you to

track the space station by hand. When

setting up your scope, make sure you have

a clear view of the entire pass.

Imaging techniquesYou dont need expensive imaging

equipment to capture the ISS. With just a

simple DSLR youll be well on your way.

DSLR and tripodWith a simple setup like this its easy to

capture the ISS as it makes its pass above.

The result will be the same as a single

bright star trail. Any digital camera can be

used as long as it is mounted to a tripod

and has a long-exposure (bulb) setting.

DSLR and telescopeYou can capture more detail by attaching

your camera to a telescope. Its far better

to use a hand-guided mount. Use the

cameras self-timer to take a burst of shots

or a single shot. As digital cameras often

have larger chips than webcams, youre

more likely to capture the ISS in a

single frame.

CCD camera and telescopeWith CCDs snapping thousands of frames

during a pass, you will capture

far more detailed images using this

method. Once again, use a hand-guided

mount to track the space lab and stack

the frames during postproduction using

software such as RegiStax.

An example of an ISS observing chart fromthe Heavens Above website

Learn how to find, observe and evencapture images of the orbiting space lab

A detailed, face-on view of the ISS takenwith a CCD camera

NASA,

MARTINLEWIS

COVERDISCDECEMBER 103

SKILLS