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Just for completeness….
Here’s the full image of the first spiral image (I’ve re-sized the image but there has been no processing). Also, the next two meteors in this sequence from the night. 2nd is fainter, mid upper right (11 x 30 secs later) and 3rd was another bright meteor (a further 6x 30 secs later). If it was wind it would needed to have been very contstant to generate the identical oscillatory effect and in any case the whole rig was low down sheltered by a wall and the car. This still does not guarantee absolutely there was no wind effect but I did deliberately try to minimise it.
I might go with shutter slap but with that vibration, hopefully, dying down quickly it would mean ALL of the spirals would need to be caught just in the first few seconds as the mirror moved and the shutter opened. Again not impossible but the odds must be fairly long…
Next time I’ll be taking a tripod with tubular legs I can fill with sand to dampen out vibrations.
If nothing else it adds a bit of drama to the image!
Cheers,
Bill.
Hi,
Yep it’s a curious effect all right. On twitter I’ve been presented with many explanations and reasons. The first night I was observing it was so windy I elected not to use the DSLRs for this very reason, 2nd night (peak) was much less windy although there were some short spells of gusty winds and the 3rd night was fairly windy again (but I haven’t got to checking all of the third night images yet!).
What would clinch it would be some double station imaging with suitably placed cameras. I’ll just need to go back to do some more imaging…. 😉
cheers,
Bill.
Hi,
Although the document is referencing solar observing have a look at this: http://www.spectrohelioscope.org/net/spectro.pdf
It’s essentially the same design as Cristian Buils work (a Littrow is a Littrow….) but using very basic components. I built this out of thin plywood and other scrap. I even used the objective from and old pair of binoculars, just like the spec and the only thing I bought was a “b” grade grating from Edmund Optics. It worked brilliantly! I even used it in demos about spectroscopy. You could beef up the design for telescope mounting without too much difficulty but without a way to view the slit it’s akward to use for stellar astronomy ( I tried and gave up…).
Anyway, it’s a very basic and cheap way to start.
cheers,
Bill.
Great stuff! Glad to see more spectro stations getting results now.
Whats the set up (lens/grating?)
cheers,
Bill.
Hi,
Thanks Alex, further to my email about Nemetode, since I first pointed a watec camera at the sky in winter of 2005/2006, revolution is the only word to describe whats been going on in meteor astronomy over those years. Next year, will be a decade of meteor spectrosopy from my place. I enjoy reading old astronomy books and my latest one, from the late 50’s has the line “meteor spectroscopy is the greatest challenge, there are no more than a few score of specta available to researchers…it is nearly impossible to identify individual lines…” The other really curious thing from that book is a table one line of which states that only 2% of meteors show lines of sodium. The hundreds that I now have show the exact reverse! there are very few that DON’T show sodium. I use it as one of the standard markers! How times change…
Roll on the Geminids but I’m going to try and not break any more bones on my way to observing!
cheers,
Bill.
Ha ha! when I saw the various graphics for it Rendevous with Rama was the very first thing I thought of!
By way of a comparison here’s the Leonid composite spectrum image and the best Lyrid one I got this year.
The change in velocity certainly affects the ablation heights and thus the appearence of the 557.7nm forbidden O Line.
(I’m hoping Alex will have some info on the heights of the Lyrids as determined by the Nemetoders…)
This line is a very useful rough and ready diagnostic tool!
cheers,
Bill.
Hi,
That is excellent news, I wonder what the final flare mag would have been. I’d have thought it brighter than -1.5 to give the spectrum it did. Applying my own principles of comparative spectroscopy I overlaid Williams and my own and the correspondance is excellent.
The varying gradients are due to flat field calibration issues. I’ll need to investigate this a bit more however it was an interesting catch with the rapid changes to the metal lines over essentially a single frame.
Seeing your fov I’ll try lowering my camera a bit, They’re all quite high to avoid light pollution diffraction issues, I’ll see if I can get a way with it.
I’m a bit dissapointed I never caught a thing with my dslr rig. I had thw two cameras with the LC shutters on for 8 hours! There were a few periods with some high cloud but 16/17 turned out to be a decent nights observing.
Cheers,
Bill.
Thanks to the efforts of Mike and William this is looking like a good candidate. Whilst there is still a timing issue on my part the az and alt of my camera are in the correct direction.
Due to resizing the image to fit it’s a bit difficult to see the numbers on the graphic. The meteor trail starts at 97 km and decends to 90km over a 30km path.
Image courtesy of Mike Folan.
cheers,
Bill.
Hi,
Perhaps not “confident” as there is still a timing error but the trail length and relatively slow speed make it “definite” maybe….
Certainly was travelling in the correct direction for a possible N Taurid.
cheers,
Bill.
Hi,
The shutters were supplied by this company.
However, I got mine via a friend in the Netherlands as he was ordering several for the same use. I don’t know for sure but there may have been a minimum order quantity. A single shutter is around Euro 200-250 depending on model.
cheers,
Bill.
Hi,
I still haven’t fully reviewed all of the catches. For one random night I caught almost everything, stony spectra, Fe spectra, multiple peak ones, “melters” and lots of “normals”.
Last night I had a window of a couple of hours of really good conditions. Decided to forego video and set up some DSLR’s with the LCD chopping shutters. 480 images over 4 hours and didn’t catch a thing! ;-((
What was realy interesting and pretty cool was the couple of sats I caught that I may have said were meteors. The absence of chops belies their true speed on the sky and instantly reveals them as sats.
I’ve had to stretch this but it shows the point. A bit symetrical for a meteor but it would have been a maybe…
I’ll drop Dave/Dennis a email if I find anything else of note. I’ve got two cameras covering your direction now. One integrated light and one spectrum system. Both 12mm f0.8’s so slightly tight on the fov. We’ll get something eventually.
Cheers,
Bill.
Here are the light curves. Note the data is smoothed so loses some intensity data. Also “time” is given to indicate the temporal evolution direction.
First two have a fainter first component then brighter second component and third one is the reverse, bright then fainter. So this indicates that there is no universal model for what should happen with binary component meteors.
See
Meteoroid structure and ablation implications
from multiple maxima meteor light curves.Roberts, I.D.1, Hawkes,R.L.1, Weryk,R.J.2, Campbell-Brown,M.D.2,
Brown,P.G.2;3, Stokan, E.2 and Subasinghe, D.21Department of Physics, Mount Allison University, Sackville, Canada (email: rhawkes@mta.ca)
2Department of Physics and Astronomy, University of Western Ontario, London, Canada
3Centre for Planetary Science and Exploration, University of Western Ontario, London, Canadafrom Proceedings of the Meteoroids 2013 Conference
Aug. 26-30, 2013, A.M. University, Poznan, Poland
Jopek T.J., Rietmeijer F., Watanabe J., Williams I.P., ed.for further ideas on whats going on.
cheers,
Bill.
Hi,
Yes, all of the WATEC camera’s I use are interlaced. This is both a blessing and a curse! Sometimes the interlacing is useful for timing but of course when looking at photometric issues like the light curve the “chopping” is a nuisance.
Doing some mathematic filtering/smoothing helps the appearence but one looses a little of the genuine rapidity of the onset.
cheers,
Bill.
Caught another of these distinctive fellows.
Motion is top to bottom. Spectrum…
…Colourised…
…and light curve (smoothed)…
Older text books quote that iron meteors comprise a few perecent of those observed. Now it’s known how they behave in general terms on video we’ll see how many turn up in the coming months/years. Maybe confirm historical observations or suggest an update is required.
cheers,
Bill.
Hi,
I’m afraid I continue the tradition in astronomical circles of giving every experiment a name based on a ridiculous acronym.
NOVEX stands for NarrOw field of View EXperiment…. ;-))
The smaller FOV’s yield meteors that zip through but if you’re lucky enough to catch one at it’s end you can see some remarkable effects.
As for the iron meteors, they behave the way they do because of the very specific thermo-mechanical properties of the iron/nickel (as you would expect) but you’re correct it cannot be extrapolated the other way as the interface between the meteoroid and the atmosphere has so many variables in terms of both composition and mechanics.
cheers,
Bill.
Had a very good nights observing on the 5/6 October. Caught some more meteors with very rapid onsets, perhaps more Fe meteors. Unfortunately didn’t get any spectra of these. However did pick up a few other equally interesting ones. The best had very bright oxygen emission coming from several lines.
Video is here https://youtu.be/EqVVNOun3YI
cheers,
Bill.
Forgot to include the actual light curves..!
These are simple sections taken along the meteor trails using IRIS.
The onset of light emission is dramatic, especially in the first one.
Cheers,
Bill.
