Transit of Venus light curve: exoplanet detection demo

Ok, so Venus isn’t an extrasolar planet (exoplanet), but I thought this would be a cool thing to try.  A while ago I put together a time-lapse movie of the 2012 Transit of Venus.  More recently, during a public talk on exoplanets, I saw a video someone had made to demonstrate the transit method used to detect planets around other stars.  The video looked a bit like my time-lapse, except that it was a simulation.  I thought, “why not try to get a real light curve from my transit footage?”

Astrocinemagraphy (not a real term)

Here, I just had a stab at making a cinemagraph of the Anglo-Australian Telescope (AAT) using frames from colleague Ángel R. López-Sánchez‘ excellent time-lapse movie “A 2dF night at the Anglo-Australian Telescope”.  Ángel is an astrophysicist at the Australian Astronomical Observatory (AAO) and spends a lot of time using the AAT for his research.

As for the image, I made it with Adobe After Effects.

Transit of Venus 2012 time-lapse

Venus passed in front of the sun on 6th June 2012, and all the while I was happily photographing it from tropical North Queensland.  Here is the time-lapse of all the photos I took throughout the day.  The music is by Kevin Macleod – thanks Kevin!

Canon 5D Mark III astrophotography

“The Bulge”; Single exposure, ISO 5000, 24 mm, f/2.8, 20 sec

If anything shows off the low light capabilities of the 5D Mark III, it’s astrophotography. For me this doesn’t go any deeper than wide angle shots of the night sky, but luckily I got to try out the camera on some really dark nights at Siding Spring Observatory earlier this year. What strikes me about the 5DIII’s high ISO noise performance is how much colour and contrast detail you can retain. Bear in mind all these shots are at f/2.8.. if only I had a 1.4!

Photographing the Transit of Venus 2012

The transit of Venus 2012: Six frames at equal intervals throughout the transit, starting here with second contact (top left), then along each row until third contact (bottom right). The sun is shown with its south pole at the top, and in sunny false colour of course :)

On 6 June 2012, Venus passed directly between Earth and the Sun. This ‘transit’ won’t happen again until 2117, so I’m happy that I got some photos of it! I was asked to write a few words on my experience for the August 2012 issue of the AAO Observer newsletter, so in lieu of rehashing the same story, here’s what I wrote for the article.

PIR motion sensors for time-lapse photography

Using a household security sensor to trigger time-lapse cameras “when stuff is happening”

How do you efficiently capture something about as big as a truck being sporadically hand assembled over a period of one year?  This is a question I recently faced when setting up time-lapse cameras on a major instrumentation project at the Australian Astronomical Observatory (AAO).

A typical time-lapse approach is to take photos at fixed intervals for the duration of whatever process you’re trying to capture.  The AAO’s assembly schedule for HERMES, a high resolution astronomical spectrograph, didn’t lend itself to this approach for three reasons: i) nothing was going to happen on evenings or weekends; ii) there would be many ‘dead’ periods when work was being done outside of the main assembly area and therefore out of shot; and iii) it would go on for a year, which meant camera shutter life might have become a limiting factor.  What I needed was for photos to be taken only when work was being done, and to do so at short intervals so that these events translated into a reasonable number of frames in the final video.

I decided to use a Passive Infra-Red (PIR) motion sensor to govern when the cameras were triggered.  These sensors are used all the time for outdoor security lights, and they’re super cheap (about $20 from a DIY store).  By using a PIR sensor, the cameras would only fire when someone was in the room, i.e. “when stuff was happening”.