HOW TO TRACK AND PHOTOGRAPH SECRET SPACECRAFT

Earlier this year, Dutch science journalist and satellite tracker Ralf Vandebergh successfully snagged detailed images of the X-37B in low orbit using a hand-tracking method – catching sight of the vehicle and guiding his 25 cm reflector telescope manually – and video-based imaging techniques. Want to capture a satellite, booster rocket, or the ISS in action? Follow Vandebergh’s lead. – Eric Adams

1 CHOOSE YOUR SCOPE

Larger-aperture telescopes create brighter, more detailed images, but even those with apertures as small as 100, 150, or 200 mm from Celestron, Meade, or Orion can bag images of larger objects such as the ISS.

2 ATTACH A CAMERA

Vandebergh uses a dedicated astronomical CCD camera, but simple webcams mounted above telescope eyepieces work just as well. The same goes for mirrorless or DSLR cameras attached directly to the telescope with an adapter. The goal: capture as many usable frames as possible of the objects, since the vehicle’s illumination varies as it moves in and out of direct sunlight. Eventually, the best and most detailed frames are processed into the final products.

3 FOLLOW THROUGH A FINDER

You’ll want a wide-angle, low-magnification finder telescope attached to the primary scope. That’s how you’ll actually acquire and track your target – not through the scope itself. (The higher magnification makes it virtually impossible.) Let the camera run while you keep the object centred in the finder scope. If they’re aligned properly, the object should end up nicely centred in the video frames.

4 KEEP A STEADY HAND

The hard part is panning smoothly along with fast-moving targets. Keep your scope on a stable mount with a smooth action that you have practised sweeping across the sky, such as a Dobsonian-style reflector on a bearing-supported box mount. ‘The ISS travels at 1° per second when it passes overhead, which is two full Moon diameters per second,’ Vandebergh says. ‘Objects in lower orbits, including the X-37B, move even faster.’

5 LOCATE YOUR TARGET

Vandebergh uses astronomical software that includes satellite positions, such as CalSky, so he can anticipate when and where they’ll pass over. But any planetarium app with satellite data will work. As the object comes over the horizon, start your camera and follow along. Just keep your screens dim and the software switched to ‘astro mode’ so you can preserve your night vision. You’ll need to see the target with the naked eye before flagging it with the finder.