Hi, Indeed, I was a bit confused as to why I had a folder marked "meteor spectrum" on the PC in question. However it was good to see some progress has been made.
...and in the way of progress, to save me re-typing the same stuff, I've put some more Quadrantid material on the BAA website which I should have put on here first. I hang my head in shame but I am getting lazy in my old age!
I think this is pretty cool. It really is close to front line meteor science and initially I didn't think it would be possible to do such things with the watecs. Great big colourful spectra from wee crappy ones do grow...
I will post the stuff here in due course, maybe next weekend, as I'm busy for the rest of the week. cheers, Bill.
Yes, Thats the way diffraction gratings work. It's a subtle idea but since meteors are generally "skinny" they act as their own slit. So the grating diffracts this "slit" image through an angle proportional to the number of grooves and wavelength thus generating the spectrum.
Not much in the way of clear sky recently. Had a few hours over the weekend. Caught this spectrum.
It was quite faint but what is interesting is the brightness of the OI line at 557.7nm. This is a "forbidden" transition from oxygen in the atmosphere. Usually only seen on fast meteors that ablate higher than average, ~100km + up. It is only at this height the conditions allow the oxygen atoms to stay excited long enough to emit the meta stable photons ( lifetime 0.74 seconds) before losing the energy through collisions.
The glow from this emission decays rapidly but a few "lifetimes" is a couple of seconds. the train was still fading when the video cut out after 40 frames, about 1.5 seconds. So this was probably coming at us head on (0508UT) , very fast and ablated fairly high up.
Cheers Alan, This is one reason why I really like presenting the spectra as the synthetic colour versions. A standrd graphical spectrum just wouldn't have had the same impact or conveyed the colour information.
I meant to add that this colour is the same as the green tint in the aurora and it happens at the same altitude for the same quantum physics reasons!