With the eta Aquarid shower in progress I decided to get up early this morning and shoot some meteors in a timelapse and use the time from each photo identify the corresponding infrasound signal.
Sounds simple in a statement like that.
It turned out more difficult than expected, and partly due to some rookie mistakes.
When I first hatched the idea of using timelapse images to time the meteors, I envisaged the camera pointing to the zenith. Intuitively I knew that was the best place for it because that's where the meteors will be closest.
However, it's the eta Aquarids... so I pointed the camera at the radiant and didn't think about it enough.
Next time... at the zenith!
Not capturing at the zenith increases the distance to the captured meteor. This does a couple of things:
- it decreases the signal strength;
- it increases the sound travel time, and so increases the timing errors.
The session was successful in that I learned what to do next time. It was not very successful for correlating the meteor images to the infrasound however. The signals were too faint, so mired in noise if detectable at all, and the compound errors from estimating expected heights of meteors and angle of elevation meant it was not possible to clearly identify a single signal that corresponded to the image.
It was also the first time I shot a timelapse with this camera and used the in camera timelapse function rather than my old interval timer dongle. Not being familiar meant the interval between shots was longer than intended. I thought I set 1s between shots but it ended up much longer, so with 15s exposures about 50% of time was missed.
I only realised how much by comparing the gap in a satellite trail between shots. Noise reduction was turned off so that wasn't the culprit.
Attached are my calcs and notes. I didn't get as many shots as I intended as the clouds rolled in, but it was better than nothing.
Al.
