Bill Ward


Thanks Jack.

It gets better….!

Whilst concentrating on the flare as it had so many lines I didn’t really pay attention to the bright pair that ran close to the bottom of the image and through the camera ID text.

Taking a closer look revealed something remarkable. Since I started regular meteor spectroscopy around 2007 I’ve had the rather arbitrary goal of getting to a system that would resolve the bright green Mg triplet ~517nm. It’s tough to do completely!

When I chopped up the image and fitted the lines, it turns out that the “pair” is actually a partial resolution of the triplet! The 516.73nm and 517.27nm are just too close for this lens/grating/seeing combo but at the 1nm FWHM and 0.46nm/pix level it is just enough to see the 518.36nm line as separate, just over 1nm (2 pixels) between them. Here’s a plot with the brighter lines identified.

Well pleased with that!