21 December 2017 at 11:35 am #573908
The Geminids put on an impressive show from Tenerife. I determined the ZHR to be 128 +/-11. There were several meteors per minute at some points.
The interesting thing about this years display is that modelling done by Ryabova and Rendtel indicated that this year the Earth might encounter particles shed from the parent body Phaethon at its perihelion passage in 2009.
The standard theory is that the particles from Phaethon are well “baked” due to their close perihelion distance so they have less volatiles in their make up. This is usually the explantion for low sodium line strength in their spectrum.
I caught over 30 spectra on my excusrion with 10 being viable. Below is a spectrum of the brightest fireball. It is clear this has quite a strong Na line (5890A on the graph) relative to the Mg (5175A) line so just perhaps this is one of those “fresher” particles that has not been baked out quite so much ….?
I’ll get a better handle on this when I fully process all the others but it’s a fascinating start!
Attachments:8 January 2018 at 10:39 pm #578939
I’ve put a short video on YouTube of this fireball and a colourised version as well.
Certainly the best spectrum I’ve had in several years!
The other analysis is progressing but it’s a lot more work than I anticipated… 😉
Bill.9 January 2018 at 12:23 am #578941Eric WatkinsParticipant
An impressive short film that captivates what can be done and why I’m very interested in getting into this area of research this coming Spring.
Regards,Eric14 March 2018 at 1:04 am #579226
Months on I’m still working through the Geminids 2017! This is a crop from the composite video image. 20171215:011300UT. (Correcting the smile is just another little challenge….)
However If you look to the left of the image the first two bright, closely spaced lines are the H and K ionised calcium lines. I am both surprised and extremely please to be getting this resolution with an objective mounted grating. Shows that a good fall of meteor across the fov (pretty much luck) can make a significant difference to the results! Considering some of the comments I’ve been exploring some new reduction strategies. Here’s a non instrument corrected spectrum with the line ID’s as best as I can tell.
If only all meteors were the same mass, traveling at the same velocity and were recorded in the zenith things would be just so much easier (but probably not as much fun!), sigh… ;-))
Bill.14 March 2018 at 12:31 pm #579229Jack MartinParticipant
Nice spectrum and excellent movie on U tube.
Essex UK15 March 2018 at 8:55 pm #579231
Thanks, it’s taken a decade to get it all together and make it fairly routine. If you look through my other meteor video’s on YouTube you’ll see one of the developments over the years. Doesn’t seem like ten years, I can still remember seeing that very first really crude spectrum at 320×240 resolution and thinking this is the future. When you look at the numbers it is staggering the immense jump that has happened. HUNDREDS of hours over decades to record photographically just those few exceptionally bright fireballs producing spectra. Now, even at this time of year I get several per night (when it’s clear ;-() and dozens during meteor showers.
Now that the pros are using my type of video system they get even more since they run a lot more cameras from considerably better sites! Looking at the journals, meteor spectroscopy papers are now regular. The game is now trying to build up classifications with a large number of spectra that all look pretty similar. The first papers on this have already appeared. The differences are there but it’s a subtle game at that.
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