Author: dvida

42 sprites recorded in one night from Hum, Croatia

42 sprites recorded in one night from Hum, Croatia

The RMS systems are very prolific when it comes to meteors, but last night the camera in Hum, Croatia recorded a distant thunderstorm storm and 42 sprites above it!

Sprites are large-scale electrical discharges that occur high above thunderstorm clouds, or cumulonimbus, giving rise to a quite varied range of visual shapes flickering in the night sky. They are usually triggered by the discharges of positive lightning between an underlying thundercloud and the ground.

Here are stacks and individual images of the recorded sprites:

All-sky systems

All-sky systems

We have recently started experimenting with all-sky lenses on IMX291 based cameras. The results are promising, we get magnitude +2.5 stars at 25 frames per second, and at 720p the all-sky lens gives an average pixel scale of 15 arcmin/px.

Here is how the current setup looks like (we are still working on the dome design):

IMX291 with an all-sky lens

And here are the detected meteors in one night of observation:

Detected meteors on an all-sky lens.

We were also able to perform the astrometric calibration using our universal method, here are the residuals (in pixels) of 15,000 star positions detected throughout the night as the function of the distance from the zenith (in degrees):

All-sky astrometric residuals.

As it can be seen, the astrometric residuals are on the order of 0.2 px, although the residuals vary across the range of zenith angles. We consider the quality of this calibration to be satisfactory for computing trajectories of meteorite-dropping fireballs.

Stay tuned!